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Solution Concentration and pH - Practice Questions (36)

Question 1: 1. At $25 ^ { \circ } \mathrm { C }$, the concentration of $\mathrm { OH } ^ { - }$ ionized from the...

1. At $25 ^ { \circ } \mathrm { C }$, the concentration of $\mathrm { OH } ^ { - }$ ionized from the water in the $\mathrm { OH } ^ { - }$ solution is $1 \times 10 ^ { - 12 } \mathrm {~mol} / \mathrm { L }$, and the pH of this $\mathrm { Ba } ( \mathrm { OH } ) _ { 2 }$ solution is

  • A. A. 13
  • B. B. 12
  • C. C. 11
  • D. D. 2

Answer: B

Solution: $\mathrm { Ba } ( \mathrm { OH } ) _ { 2 }$ The $\mathrm { OH } ^ { - }$ concentration of water ionized from the $1 \times 10 ^ { - 12 } \mathrm {~mol} / \mathrm { L }$ solution is $1 \times 10 ^ { - 12 } \mathrm {~mol} / \mathrm { L }$ and the $\mathrm { Ba } ( \mathrm { OH } ) _ { 2 }$ concentration of water ionized from the $\mathrm { H } ^ { + }$ solution is [[]]. INLINE_FORMULA_5]], the $\mathrm { H } ^ { + }$ ionized by the water is $\mathrm { H } ^ { + }$ in the solution, and the $\mathrm { Ba } ( \mathrm { OH } ) _ { 2 }$ of this $\mathrm { pH } = - \operatorname { lgc } \left( \mathrm { H } ^ { + } \right) = - \lg \left( 10 ^ { - 12 } \right) = 12 ;$ solution is $1 \times 10 ^ { - 12 } \mathrm {~mol} / \mathrm { L }$. Therefore, the answer is B.

Question 2: 2. The graph represents the solubility curves of $\mathrm { X } , \mathrm { Y } , \mathrm { Z }$ thr...

2. The graph represents the solubility curves of $\mathrm { X } , \mathrm { Y } , \mathrm { Z }$ three substances, and the following statements are false ![](/images/questions/solution-ph/image-001.jpg)

  • A. A. At $t _ { 3 } ^ { \circ } C$, the saturated solution of $X , Y$ is cooled down to $t _ { 2 } ^ { \circ } C$, and more crystals are precipitated $X$
  • B. B. At $\mathrm { t } _ { 1 } ^ { \circ } \mathrm { C }$, a saturated solution of the three substances is warmed to ${ } ^ { \mathrm { t } } { } ^ { \circ } \mathrm { C }$, and the relationship between the magnitudes of the mass fractions of solutes in the solution is $\mathrm { Y } > \mathrm { X } > \mathrm { Z }$
  • C. C. Y contains a small amount of X. Y is purified by the principle of salt in sea water.
  • D. D. At ${ } ^ { t } { } ^ { \circ } \mathrm { C }$, equal masses of $X , Y$ are separately prepared into saturated solutions at this temperature, and the resulting solution masses $X < Y$

Answer: A

Solution: At $\mathrm { A } . \mathrm { t } _ { 3 } { } ^ { \circ } \mathrm { C }$, the mass relationship of the saturated solution of $\mathrm { X } , \mathrm { Y }$ cannot be determined, and the amount of crystals precipitated cannot be determined, so A is wrong; B. The mass fraction of solute in a saturated solution is related to the solubility, and the solubility of the three substances in $\mathrm { t } _ { 1 } { } ^ { \circ } \mathrm { C }$ at $\mathrm { X } , \mathrm { Y } , \mathrm { Z }$ is: $\mathrm { Y } > \mathrm { X } = \mathrm { Z }$; so the solubility of the three substances A, B and C at $\mathrm { t } _ { 1 } { } ^ { \circ } \mathrm { C }$ is: $\mathrm { Y } > \mathrm { X } = \mathrm { Z }$; so the solubility of the three substances A, B and C at $\mathrm { t } _ { 1 } { } ^ { \circ } \mathrm { C }$ is Saturated solution of solute mass fraction size relationship is: $\mathrm { Y } > \mathrm { X } = \mathrm { Z }$; after warming, X and Y solubility becomes larger, both become unsaturated solution, the solute mass fraction remains unchanged, so after warming or $\mathrm { Y } > \mathrm { X } , \mathrm { Z }$ substances after warming, solubility decreases, the solute mass fraction decreases, then the size of the mass fraction of the solute after warming is : $\mathrm { Y } > \mathrm { X } > \mathrm { Z }$ , so B is correct; C. from the figure can be seen: X solubility with the increase in temperature and increase, Y solubility by the temperature is not much, so when Y contains a small amount of X, you can use seawater salt purification Y, that is, to take the principle of evaporation and crystallization of the purification of Y, C is correct; D. $t _ { 3 } { } ^ { \circ } \mathrm { C }$ when the X solubility is greater than the solubility of Y, and the equal mass of $\mathrm { X } , \mathrm { Y }$ is greater than the solubility of Y, so it is correct to use the same principle of evaporation and crystallization of Y, C is correct. FORMULA_10]] into saturated solutions at this temperature, Y requires more water than X, so the resulting solution has a mass of $\mathrm { X } < \mathrm { Y }$, so D is correct;

Question 3: 3. Neutralize the acetic acid solution with standard sodium hydroxide solution, when the pH value of...

3. Neutralize the acetic acid solution with standard sodium hydroxide solution, when the pH value of the solution is equal to 7, then at this time

  • A. A. Acetic acid and sodium hydroxide are equal in quantity.
  • B. B. Acetic acid and sodium hydroxide are exactly neutralized
  • C. C. Excess sodium hydroxide
  • D. D. Acetic acid surplus

Answer: D

Solution:

Question 4: 4. When a strong monobasic base and a strong monobasic acid with the same concentration of substance...

4. When a strong monobasic base and a strong monobasic acid with the same concentration of substances react with each other, the solution

  • A. A. acidic
  • B. B. alkaline
  • C. C. neutral
  • D. D. You can't tell if it's acidic or alkaline.

Answer: D

Solution: Mutual reaction is divided into three cases, (1) acid excess, then the reaction of the solution shows acidic; (2) base excess, then the reaction of the solution shows basic; (3) just completely reacted, then the solution is neutral, so the acidity or alkalinity of the solution after the reaction can not be judged according to the known conditions, D is correct; Answer choice D.

Question 5: 5. When a solution of sulfuric acid with pH 5 is diluted 1000 times at room temperature, the $\mathr...

5. When a solution of sulfuric acid with pH 5 is diluted 1000 times at room temperature, the $\mathrm { c } \left( \mathrm { SO } _ { 4 } ^ { 2 - } \right) : \mathrm { c } \left( \mathrm { H } ^ { + } \right)$ in the diluted solution is approximately ( ).

  • A. A. $1 : 20$
  • B. B. 1: 2
  • C. C. 1: 1
  • D. D. $20 : 1$

Answer: A

Solution: The concentration of hydrogen ions in a sulfuric acid solution of pH 5 is $c \left( \mathrm { H } ^ { + } \right) = 1 \times 10 ^ { - 5 } \mathrm {~mol} / \mathrm { L } , c \left( \mathrm { SO } _ { 4 } ^ { 2 - } \right) = \frac { 1 } { 2 } c \left( \mathrm { H } ^ { + } \right) = 5 \times 10 ^ { - } { } ^ { 6 } \mathrm {~mol} / \mathrm { L }$, and after the solution is diluted 1000 times, the concentration of hydrogen ions cannot be less than $1 \times 10 ^ { - 7 } \mathrm {~mol} / \mathrm { L }$, but can only be infinitely close to $1 \times 10 ^ { - } { } ^ { 7 } \mathrm {~mol} / \mathrm { L }$, and the concentration of sulfate root is $c \left( \mathrm { SO } _ { 4 } ^ { 2 - } \right) = \frac { 1 } { 1000 } \times 5 \times 10 ^ { - 6 } \mathrm {~mol} / \mathrm { L } = 5 \times 10 ^ { - 9 } \mathrm {~mol} / \mathrm { L }$, so the concentration in the solution is $\mathrm { c } \left( { } ^ { \mathrm { SO } _ { 4 } ^ { 2 - } } \right) : \mathrm { c } \left( \mathrm { H } ^ { + } \right) = 5 \times 10 ^ { - 9 } \mathrm {~mol} / \mathrm { L } : 1 \times 10 ^ { - 7 } \mathrm {~mol} / \mathrm { L } = 1 : 20$, so A is correct; therefore, A is correct; A is correct. FORMULA_3]], so the diluted solution is $\mathrm { c } \left( { } ^ { \mathrm { SO } _ { 4 } ^ { 2 - } } \right) : \mathrm { c } \left( \mathrm { H } ^ { + } \right) = 5 \times 10 ^ { - 9 } \mathrm {~mol} / \mathrm { L } : 1 \times 10 ^ { - 7 } \mathrm {~mol} / \mathrm { L } = 1 : 20$, so A is correct;

Question 6: 6. At room temperature, the more acidic of the following solutions are

6. At room temperature, the more acidic of the following solutions are

  • A. A. $\mathrm { pH } = 3$
  • B. B. $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 10 ^ { - 6 } \mathrm {~mol} / \mathrm { L }$
  • C. C. $\mathrm { pH } = 5$
  • D. D. $\mathrm { c } \left( \mathrm { OH } ^ { - } \right) = 10 ^ { - 10 } \mathrm {~mol} / \mathrm { L }$

Answer: A

Solution: A. At room temperature, $\mathrm { pH } = 3$ in a solution of $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 10 ^ { - 3 } \mathrm {~mol} / \mathrm { L }$; B. $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 10 ^ { - 6 } \mathrm {~mol} / \mathrm { L }$ at room temperature; C. In a solution of $\mathrm { pH } = 5$ at room temperature, $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 10 ^ { - 5 } \mathrm {~mol} / \mathrm { L }$; D. At room temperature, $\mathrm { c } \left( \mathrm { OH } ^ { - } \right) = 10 ^ { - 10 } \mathrm {~mol} / \mathrm { L }$, according to $K _ { w } = \mathrm { c } \left( \mathrm { H } ^ { + } \right) \mathrm { c } \left( \mathrm { OH } ^ { - } \right) = 10 ^ { - 14 }$, we can know that $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 10 ^ { - 4 } \mathrm {~mol} / \mathrm { L }$; Combined with the above analysis, we can know that the solution with the largest concentration of hydrogen ions in the solution is the one with $\mathrm { pH } = 3$, so the one with the strongest acidity is A ;

Question 7: 7. Solutions have a great impact on our lives, the following solutions in which the solvent is not w...

7. Solutions have a great impact on our lives, the following solutions in which the solvent is not water are

  • A. A. iodine solution
  • B. B. saline (medicine)
  • C. C. hydrogen peroxide solution
  • D. D. Glucose Injection

Answer: A

Solution: A. Iodine is the solute in iodine solution and alcohol is the solvent; B. Saline is an aqueous solution of sodium chloride in $0.9 \%$; sodium chloride is the solute and water is the solvent; C. Hydrogen peroxide solution is an aqueous solution of hydrogen peroxide, with hydrogen peroxide as the solute and water as the solvent; D. Glucose injection is an aqueous solution of glucose, with glucose as the solute and water as the solvent; Answer choice A.

Question 8: 8. Kitchen has the following substances: (1) salt, (2) wine, (3) flour, (4) soybean oil, (5) sugar, ...

8. Kitchen has the following substances: (1) salt, (2) wine, (3) flour, (4) soybean oil, (5) sugar, (6) pasta sauce, they were put into the right amount of water, mix thoroughly, to get a solution of the

  • A. A. (1) (2) (5)
  • B. B. (1) (2) (6)
  • C. C. (3) (5) (6)
  • D. D. (3) (4) (6)

Answer: A

Solution: (1) Sodium chloride can be dissolved into water to form a homogeneous, stable mixture, i.e., a solution is obtained, correct; (2) Wine can be dissolved into water to form a homogeneous, stable mixture, i.e., a solution is obtained, correct; (3) Flour does not dissolve in water, and only a suspension can be formed by stirring the flour thoroughly in water, which is incorrect; (4) Soybean oil cannot be dissolved in water, and it can only form an emulsion when it is put into water and stirred thoroughly, which is wrong; (5) Sugar can be dissolved into water to form a homogeneous and stable mixture, i.e., a solution is obtained, correct; (6) pasta sauce can not be dissolved in water, put the pasta sauce into the water and mix thoroughly can only form a suspension, the error in line with the meaning of the question (1) (2) (5), so the answer is A.

Question 9: 9. $0.05 \mathrm {~mol} / \mathrm { L }$ solution of $\mathrm { Ba } ( \mathrm { OH } ) _ { 2 }$ wit...

9. $0.05 \mathrm {~mol} / \mathrm { L }$ solution of $\mathrm { Ba } ( \mathrm { OH } ) _ { 2 }$ with pH

  • A. A. 12.7
  • B. B. 12.0
  • C. C. 13.0
  • D. D. 13.7

Answer: C

Solution: $0.05 \mathrm {~mol} / \mathrm { L }$ of $\mathrm { Ba } ( \mathrm { OH } ) _ { 2 }$ in solution $\mathrm { c } \left( \mathrm { OH } ^ { - } \right) = 0.05 \mathrm {~mol} / \mathrm { L } \times 2 = 0.1 \mathrm {~mol} / \mathrm { L }$, then its solution $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = \frac { \mathrm { K } _ { \mathrm { w } } } { \mathrm { c } \left( \mathrm { OH } ^ { - } \right) } = \frac { 10 ^ { - 14 } } { 0.1 } = 10 ^ { - 13 } \mathrm {~mol} / \mathrm { L }$, so solution $\mathrm { pH } = - \operatorname { lgc } \left( \mathrm { H } ^ { + } \right) = - \lg 10 ^ { - 13 } = 13.0$. Answer choice C.

Question 10: 10. At room temperature, the pH of the $0.1 \mathrm {~mol} / \mathrm { LNaOH }$ solution is about

10. At room temperature, the pH of the $0.1 \mathrm {~mol} / \mathrm { LNaOH }$ solution is about

  • A. A. 10
  • B. B. 11
  • C. C. 12
  • D. D. 13

Answer: D

Solution: NaOH is a strong base and a strong electrolyte, so $0.1 \mathrm {~mol} / \mathrm { L } \mathrm { NaOH }$ is $c \left( \mathrm { OH } ^ { - } \right) = 0.1 \mathrm {~mol} / \mathrm { L }$ in the solution, so at room temperature, $c \left( \mathrm { H } ^ { + } \right) = \frac { K _ { \mathrm { w } } } { c \left( \mathrm { OH } ^ { - } \right) } = \frac { 10 ^ { - 14 } } { 0.1 } = 10 ^ { - 13 } \mathrm {~mol} / \mathrm { L }$, $\mathrm { pH } = - \lg c \left( \mathrm { H } ^ { + } \right) = - \lg 10 ^ { - 13 } = 13$ in the solution; therefore, the answer is D.

Question 11: 11. $\mathrm { N } _ { \mathrm { A } }$ represents Avogadro's constant, and the following statements...

11. $\mathrm { N } _ { \mathrm { A } }$ represents Avogadro's constant, and the following statements are correct

  • A. A. The number of $\mathrm { H } ^ { + }$ in hydrochloric acid of $\mathrm { pH } = 1$ is $0.1 \mathrm {~N} _ { \mathrm { A } }$.
  • B. B. ${ } ^ { 3 \mathrm {~N} _ { \mathrm { A } } }$ units of $\mathrm { H } _ { 2 }$ reacted sufficiently with a sufficient quantity of ${ } ^ { \mathrm { N } _ { 2 } }$ to obtain $44.8 \mathrm {~L} \mathrm { NH } _ { 3 }$ under standard conditions.
  • C. C. $12 \mathrm {~g} \mathrm { NaHSO } _ { 4 \text { 晶体中含有 } } 0.1 \mathrm {~N} _ { \mathrm { A } }$ cations
  • D. D. When sodium peroxide reacts with water to produce 0.1 mol of oxygen, the number of electrons transferred is $0.4 \mathrm {~N} _ { \mathrm { A } }$

Answer: C

Solution: A. The $\mathrm { pH } = 1$ concentration of $\mathrm { H } ^ { + }$ in hydrochloric acid is $0.1 \mathrm {~mol} / \mathrm { L }$, and the volume of the solution is unknown, so you can't calculate the amount of its substance, A is wrong; B. The reaction of ${ } ^ { 3 N _ { A } }$ with a sufficient amount of $\mathrm { H } _ { 2 }$ and ${ } ^ { N _ { 2 } }$ is a reversible reaction, which is incomplete and the amount of ammonia produced cannot be calculated, B error ; C. One molecule of sodium bisulfate contains one sodium ion and one hydrosulfate ion, and $12 \mathrm {~g} \mathrm { NaHSO } _ { 4 }$ (0.1 mol) crystals contain ${ } ^ { 0.1 } \mathrm {~N} _ { \mathrm { A } }$ cations; D. Sodium peroxide reacts with water $2 \mathrm { Na } _ { 2 } \mathrm { O } _ { 2 } ^ { 2 - } + 2 \mathrm { H } _ { 2 } \mathrm { O } = 4 \mathrm { Na } ^ { + } + 4 \mathrm { OH } ^ { - } + \mathrm { O } _ { 2 } \uparrow$ to produce 0.1 mol of oxygen, the number of electrons transferred is ${ } ^ { 0.2 \mathrm {~N} _ { \mathrm { A } } } , \mathrm { D }$ incorrect;

Question 12: 12. When an electrolyte is dissolved in water, some or all of it dissociates into free-moving (hydra...

12. When an electrolyte is dissolved in water, some or all of it dissociates into free-moving (hydrated) anions and (hydrated) cations with the "help" of water molecules. The following statements about electrolyte solutions are correct ( )

  • A. A. There must be an equal number of anions and cations in solution
  • B. B. The total number of positive charges carried by cations in a solution must equal the total number of negative charges carried by anions
  • C. C. There will be no other particles in the solution except anions and cations
  • D. D. The strength of the conductivity of an electrolyte solution is directly proportional to the charge of the ion, independent of the concentration of the solution

Answer: B

Solution: A, the number of anions and cations in the electrolyte solution are not necessarily equal but follow the conservation of charge, such as sodium sulfate solution in the presence of $\mathrm { N } \left( \mathrm { Na } ^ { + } \right) = 2 \mathrm {~N} \left( \mathrm { SO } _ { 4 } { } ^ { 2 - } \right)$, so A error; B, any electrolyte solution follows the conservation of charge, so the total number of positive charges carried by cations must be equal to the total number of negative charges carried by anions, so B is correct; C, the electrolyte solution contains molecules in addition to anions and cations, such as water molecules, if the electrolyte is a weak electrolyte, there are also solute molecules in the solution, so C is wrong; D, the size of the conductivity of the electrolyte solution is proportional to the concentration of ions and charge, and electrolyte strength has nothing to do, so D error; so the answer is B.

Question 13: 13. If you want to change the concentration of $30 \%$ to $30 \%$, you can use the method of $30 \%$...

13. If you want to change the concentration of $30 \%$ to $30 \%$, you can use the method of $30 \%$ to change the ag mass fraction of sodium nitrate solution.

  • A. A. Evaporation of solvent from $1 / 2$
  • B. B. Evaporate $a / 2 g$ solvent.
  • C. C. Add $3 \mathrm { a } / 20 \mathrm {~g}$ Sodium nitrate
  • D. D. Increase temperature to $50 ^ { \circ } \mathrm { C }$

Answer: B

Solution: A. If the mass fraction of sodium nitrate solution is $15 \%$, if you want to change its mass fraction to $30 \%$, you need to isothermally evaporate $\frac { 1 } { 2 }$ of the mass of the solution instead of $\frac { 1 } { 2 }$ of the mass of the solvent. is wrong; B. If the mass fraction of $15 \%$ of sodium nitrate solution, if you want to change its mass fraction to $30 \%$, you need to evaporate $\frac { 1 } { 2 }$ ag solvent, so B is correct; C. Let the increase in the mass of the solute for $x$, according to the mixing of the mass of the solute before the solute is equal to the mixing of the mass of the solute in the solution, get $\mathrm { ag } \times 15 \% + \mathrm { x } = ( \mathrm { ag } + \mathrm { x } ) \times 30 \%$, the solution $\mathrm { x } = \frac { 3 } { 14 } \mathrm { ag }$, that is, the increase in the solute can make $\frac { 3 } { 14 } \mathrm { ag }$ mass fraction of solute to reach $30 \%$, so B is correct. The mass fraction of solute reaches $30 \%$, so C is wrong; D. The solubility of sodium nitrate increases with temperature, increase the temperature to $50 ^ { \circ } \mathrm { C }$, the mass of the solute remains unchanged, the concentration remains unchanged, so D is wrong;

Question 14: 14. The solubility curves of two substances, A and B, are shown in the figure, and the following sta...

14. The solubility curves of two substances, A and B, are shown in the figure, and the following statements must be correct ![](/images/questions/solution-ph/image-002.jpg)

  • A. A. Point A indicates that $\mathrm { T } _ { 1 } { } ^ { \circ } \mathrm { C }$ when A's solution is saturated and B's solution is not saturated
  • B. B. Point B indicates $\mathrm { T } _ { 2 } { } ^ { \circ } \mathrm { C }$ when both solutions of substances A and B are saturated and the concentrations of the substances in both solutions must be equal
  • C. C. Point B indicates $\mathrm { T } _ { 2 } { } ^ { \circ } \mathrm { C }$ that the mass fractions of the solutes of the solutions of substances A and B are equal.
  • D. D. Point B indicates that the densities of the solutions of substances A and B must be equal at $\mathrm { T } _ { 2 } { } ^ { \circ } \mathrm { C }$.

Answer: C

Solution: A. According to the significance of the solubility curve of solid substances, point A indicates $\mathrm { T } _ { 1 } { } ^ { \circ } \mathrm { C }$ when solution B is oversaturated and solution A is not saturated, so the statement is wrong; B. According to the significance of the solubility curve of solid substances, $\mathrm { T } _ { 2 } { } ^ { \circ } \mathrm { C }$ when the solubility of the two substances A and B are equal, and are saturated solution, so the mass fraction of the solute is also equal, but the volume of the solution, the amount of solute can not be determined, so the concentration of the two solutions of the amount of material is not necessarily equal, so the option is wrong; C. According to the significance of the solubility curve of solid substances, $\mathrm { T } _ { 2 } { } ^ { \circ } \mathrm { C }$ when the solubility of the two substances A and B are equal, and are saturated solution, so the mass fraction of solute is also equal, so the option is correct; D. According to the significance of the solubility curve of solid substances, $\mathrm { T } _ { 2 } { } ^ { \circ } \mathrm { C }$, the solubility of A and B are equal, and both are saturated solution, so the mass fraction of solute is also equal. and solution, so the mass fraction of solute is also equal, because the mass and volume of the solution can not be determined, so the density of the solution of A and B are not necessarily equal, so the option is wrong; In summary, the correct option C.

Question 15: 15. With respect to the formulation of the stoichiometry problem (let $N _ { \mathrm { A } }$ be the...

15. With respect to the formulation of the stoichiometry problem (let $N _ { \mathrm { A } }$ be the value of Avogadro's constant), one of the following statements is correct

  • A. A. When $0.2 \mathrm {~mol} \mathrm { Cl } _ { 2 }$ is added to a solution of ${ } ^ { \mathrm { FeI } _ { 2 } }$ with 0.1 mol of solute, $\mathrm { I } ^ { - }$ and $\mathrm { Fe } ^ { 2 + }$ are oxidized.
  • B. B. At room temperature, $0.1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ ethanedioic acid solution of $\mathrm { pH } > 2$ contains more than 0.01 mol of $\mathrm { H } ^ { + }$.
  • C. C. The number of ions contained in 1 mol of molten ${ } ^ { \mathrm { AlCl } _ { 3 } }$ is $4 N _ { \mathrm { A } }$
  • D. D. 1 mol of a chain hydrocarbon with an ethyl branch contains at least 5 mol of carbon atoms in the main chain.

Answer: A

Solution: A. A solution of ${ } ^ { \mathrm { FeI } _ { 2 } }$ with a solute of 0.1 mol of $0.2 \mathrm {~mol} ^ { \mathrm { Cl } _ { 2 } } , { } ^ { \mathrm { I } ^ { - } }$ is preferentially oxidized, consuming 0.1 mol of $\mathrm { Cl } _ { 2 }$, and then $\mathrm { Fe } ^ { 2 + }$ is oxidized, A is correct; B. At room temperature, $0.1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$, $\mathrm { pH } > 2$ of the ethanedioic acid solution, the concentration of hydrogen ions is less than $0.01 \mathrm {~mol} / \mathrm { L }$, and there is no volumetric data, so it is not possible to find the number of $\mathrm { H } ^ { + }$, B. Wrong; C. Aluminum chloride is a covalent compound, and the molten ${ } ^ { \mathrm { AlCl } _ { 3 } }$ crystals contain no ions, C is wrong; D. In 1 mol of a chain hydrocarbon with an ethyl branch, the main chain contains at least 4 mol of carbon atoms, e.g., $2 -$ ethyl- $1 -$ butene, D is wrong;

Question 16: 16. The following narratives are correct ( )

16. The following narratives are correct ( )

  • A. A. The $\mathrm { pH } = \mathrm { a }$ of a $\mathrm { CH } _ { 3 } \mathrm { COOH }$ solution, and the $\mathrm { pH } = \mathrm { b }$ of the solution after diluting this solution by a factor of 1, is $\mathrm { a } > \mathrm { b }$
  • B. B. At $25 ^ { \circ } \mathrm { C }$, $0.1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ the hydrogen sulfide solution is more electrically conductive than an equal concentration of sodium sulfide solution
  • C. C. At room temperature, $1.0 \times 10 ^ { - 3 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ hydrochloric acid $\mathrm { pH } = 3.0,1.0 \times 10 ^ { - 8 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ hydrochloric acid $\mathrm { pH } = 8.0$
  • D. D. At room temperature, if $1 \mathrm {~mL} \mathrm { pH } = 1$ of hydrochloric acid is mixed with 100 mL of NaOH solution, the $\mathrm { pH } = 7$ of the solution is $\mathrm { pH } = 11$ of the NaOH solution.

Answer: D

Solution: A, an acetic acid solution of $\mathrm { pH } = \mathrm { a }$, after diluting this solution by 1 times, the concentration of hydrogen ions in the solution decreases and the pH of the solution increases, then $\mathrm { a } < \mathrm { b }$, so A is wrong; B. Hydrogen sulfide is a weak electrolyte, and sodium sulfide is a strong electrolyte, so at the same concentration hydrogen sulfide solution is weaker than sodium sulfide solution of equal concentration, so B is wrong; C, at room temperature, $1.0 \times 10 ^ { - 3 } \mathrm {~mol} / \mathrm { L }$ hydrochloric acid of $\mathrm { pH } = 3.0$, and $1.0 \times 10 ^ { - 8 } \mathrm {~mol} / \mathrm { L }$ hydrochloric acid for the acid solution, then the pH of the solution can only be infinitely close to 7, it is not possible for 8, so C error; D, $\mathrm { pH } = 1$ the concentration of hydrochloric acid is $0.1 \mathrm {~mol} / \mathrm { L }$, let the concentration of sodium hydroxide solution is c, then: $0.1 \mathrm {~mol} / \mathrm { L } \times 0.001 \mathrm {~L} = 0.1 \mathrm { c }$, the solution is: $\mathrm { c } = 0.001 \mathrm {~mol} / \mathrm { L }$, then the $\mathrm { pH } = 11$ of sodium hydroxide solution, then the $\mathrm { pH } = 11$ of the $\mathrm { CH } _ { 3 } \mathrm { COOH }$ is the concentration of sodium hydroxide solution. FORMULA_9]], so D is correct; therefore, D is chosen. [点睛]无论酸碱溶液,无限稀释时, pH只能无限接近于7,不能够超越7.

Question 17: 17. At room temperature, when hydrochloric acid of equal concentration and volume is completely neut...

17. At room temperature, when hydrochloric acid of equal concentration and volume is completely neutralized with $\mathrm { pH } = 9$ and $\mathrm { pH } = 10$ ammonia, the volume of $\mathrm { NH } _ { 3 } \cdot \mathrm { H } _ { 2 } \mathrm { O }$ consumed is $\mathrm { V } _ { 1 }$ and [$\mathrm { V } _ { 2 }$ respectively. INLINE_FORMULA_4]], and the following relationship is correct

  • A. A. $V _ { 1 } = 10 V _ { 2 }$
  • B. B. $\mathrm { V } _ { 1 } > 10 \mathrm {~V} _ { 2 }$
  • C. C. $V _ { 1 } < 10 V _ { 2 }$
  • D. D. $\mathrm { V } _ { 2 } > 10 \mathrm {~V} _ { 1 }$

Answer: B

Solution: $\mathrm { pH } = 9$ in ammonia at room temperature $\mathrm { c } _ { 1 } \left( \mathrm { OH } ^ { - } \right) = 10 ^ { - 5 } \mathrm {~mol} / \mathrm { L } , \mathrm { pH } = 10$ in a solution of $\mathrm { c } _ { 1 } \left( \mathrm { OH } ^ { - } \right) = 10 ^ { - 5 } \mathrm {~mol} / \mathrm { L } , \mathrm { pH } = 10$ $\mathrm { C } _ { 2 } \left( \mathrm { OH } ^ { - } \right) = 10 ^ { - 4 } \mathrm {~mol} / \mathrm { L }$ in a solution of $\mathrm { C } _ { 2 } \left( \mathrm { OH } ^ { - } \right) = 10 ^ { - 4 } \mathrm {~mol} / \mathrm { L }$ , a weak electrolyte, the greater the concentration of the solution, the less the degree of the weak electrolyte, so that $\mathrm { c } _ { 2 } \left( \mathrm { NH } _ { 3 } \cdot \mathrm { H } _ { 2 } \mathrm { O } \right) > 10 \mathrm { c } _ { 1 } \left( \mathrm { NH } _ { 3 } \cdot \mathrm { H } _ { 2 } \mathrm { O } \right)$, and because the amounts of hydrochloric acid are equal, so $c _ { 1 } \left( N H _ { 3 } \cdot H _ { 2 } O \right) \cdot V _ { 1 } = c _ { 2 } \left( N H _ { 3 } \cdot H _ { 2 } O \right) \cdot V _ { 2 }$, then $V _ { 1 } = \frac { c _ { 2 } \left( N H _ { 3 } \cdot H _ { 2 } O \right) } { c _ { 1 } \left( N H _ { 3 } \cdot H _ { 2 } O \right) } \cdot V _ { 2 } > 10 V _ { 2 }$, and the answer is choice B.

Question 18: 18. At room temperature, the hydroxide ion concentration of a solution of HCl of pH 5 mixed in equal...

18. At room temperature, the hydroxide ion concentration of a solution of HCl of pH 5 mixed in equal volume with a solution of HCl of pH 2 is closest to ( ).

  • A. A. $2 \times 10 ^ { - 12 } \mathrm {~mol} / \mathrm { L }$
  • B. B. $1 / 2 \left( 10 ^ { - 9 } + 10 ^ { - 12 } \right) \mathrm { mol } / \mathrm { L }$
  • C. C. $\left( 10 ^ { - 9 } + 10 ^ { - 12 } \right) \mathrm { mol } / \mathrm { L }$
  • D. D. $1 / 2 \left( 10 ^ { - 5 } + 10 ^ { - 2 } \right)$

Answer: A

Solution: $\mathrm { pH } = 5$ in HCl solution $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 1 \times 10 ^ { - 5 } \mathrm {~mol} / \mathrm { L } , \mathrm { pH } = 2$ in HCl solution $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 1 \times 10 ^ { - 2 } \mathrm {~mol} / \mathrm { L }$. After mixing, the hydrogen ion concentration in the mixed solution is $= \frac { \left( 10 ^ { - 5 } + 10 ^ { - 2 } \right) } { 2 } \mathrm {~mol} / \mathrm { L }$, then the $\mathrm { c } \left( \mathrm { OH } ^ { - } \right) = \frac { 10 ^ { - 14 } } { \left( 10 ^ { - 5 } + 10 ^ { - 2 } \right) } \mathrm { mol } / \mathrm { L } = 2 \times 10 ^ { - 12 } \mathrm {~mol} / \mathrm { L }$ in the solution is $\mathrm { c } \left( \mathrm { OH } ^ { - } \right) = \frac { 10 ^ { - 14 } } { \left( 10 ^ { - 5 } + 10 ^ { - 2 } \right) } \mathrm { mol } / \mathrm { L } = 2 \times 10 ^ { - 12 } \mathrm {~mol} / \mathrm { L }$, and option A meets the question.

Question 19: 19. The graph shows the titration curve for the titration of 20.00 mL of hydrochloric acid of unknow...

19. The graph shows the titration curve for the titration of 20.00 mL of hydrochloric acid of unknown concentration (phenolphthalein as indicator) with $0.1000 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ standard NaOH solution. The following statement is correct ( ) ![](/images/questions/solution-ph/image-003.jpg)

  • A. A. Concentration of hydrogen ions ionized from water: $a > b$
  • B. B. The concentration of hydrochloric acid is $0.0100 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$
  • C. C. When the indicator changes color, the hydrochloric acid reacts completely with the NaOH solution.
  • D. D. When 10.00 mL of NaOH solution is added dropwise, the mixture's $\mathrm { pH } = 1 + \lg 3$

Answer: D

Solution: A. The concentration of hydrogen ions ionized from water: $\mathrm { b } > \mathrm { a }$, because the $\mathrm { H } ^ { + }$ concentration in the mixture at point b is small, and the inhibition of the ionization of water is small, so A is wrong; B. Observing the titration curve, we can see that the concentrations of hydrochloric acid and sodium hydroxide solution are equal, so the amount of hydrochloric acid is the same as that of sodium hydroxide solution. concentration is $0.1000 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$, so B is wrong; C. When the indicator changes color, because the range of phenolphthalein's color change (pH) is $8.2 \sim 10$, so hydrochloric acid and NaOH solution are not exactly completely reacted, so C is wrong; D. When 10.00 mL of NaOH solution is added, the total volume of the mixture is 30.00 mL, and the ${ } ^ { c } \left( \mathrm { H } ^ { + } \right)$ in the mixture is ${ } ^ { c } \left( \mathrm { H } ^ { + } \right)$. $\frac { 1 } { 30 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ in the mixture is $\mathrm { pH } = 1 + \lg 3$, so D is correct;

Question 20: 20. $25 ^ { \circ } \mathrm { C }$ at $c \left( \mathrm { H } ^ { + } \right) = 1 \times 10 ^ { - 12...

20. $25 ^ { \circ } \mathrm { C }$ at $c \left( \mathrm { H } ^ { + } \right) = 1 \times 10 ^ { - 12 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$, the pH of a solution ionized from water may be

  • A. A. 12
  • B. B. 7
  • C. C. 6
  • D. D. 2 or 12

Answer: D

Solution: $25 ^ { \circ } \mathrm { C }$ when $c \left( \mathrm { H } ^ { + } \right) = 1 \times 10 ^ { - 12 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 } < 1 \times 10 ^ { - 7 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ is ionized from water in a solution, indicating that water ionization is inhibited and the solution may be a base solution or an acid solution. If the solution is an alkali solution, then the solution is $c \left( \mathrm { H } ^ { + } \right) = 1 \times 10 ^ { - 12 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 } , \mathrm { pH } = 12$; if the solution is an acid solution, then the solution is $c \left( \mathrm { H } ^ { + } \right) = 1 \times 10 ^ { - 2 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 } , \mathrm { pH } = 2$; therefore, choose D.

Question 21: 21. Given $\mathrm { N } _ { \mathrm { A } }$ as the value of Avogadro's constant, the following sta...

21. Given $\mathrm { N } _ { \mathrm { A } }$ as the value of Avogadro's constant, the following statement is correct

  • A. A. The number of gas molecules contained in ${ } ^ { 2.24 \mathrm { LH } _ { 2 } }$ and ${ } ^ { 2.24 \mathrm { LCl } _ { 2 } }$ after full reaction is $0.2 \mathrm {~N} _ { \mathrm { A } }$
  • B. B. The number of neutrons contained in a mixture of $0.1 \mathrm {~mol} { } ^ { 14 } \mathrm { NO }$ and ${ } ^ { 14 } \mathrm { CO }$ is $1.5 \mathrm {~N} _ { \mathrm { A } }$
  • C. C. 28 g A mixture of ethylene and propylene contains the number of C-H bonds $4 \mathrm {~N} _ { \mathrm { A } }$
  • D. D. $\mathrm { pH } = 1$ of $\mathrm { H } _ { 2 } \mathrm { SO } _ { 4 }$ solution containing $\mathrm { H } ^ { + }$ the number of $0.1 \mathrm {~N} _ { \mathrm { A } }$

Answer: C

Solution: A. The state of the gas is not specified, so it cannot be calculated; B. A ${ } ^ { 14 } \mathrm { NO }$ molecule and a ${ } ^ { 14 } \mathrm { CO }$ molecule contain 15 and 16 neutrons, respectively, so the number of neutrons in the gas mixture is $1.5 - 1.6 \mathrm {~N} _ { \mathrm { A } }$, which is wrong; C. If all 28 g are ethylene, then the number of $\mathrm { C } - \mathrm { H }$ bonds is $\frac { 28 \mathrm {~g} } { 28 \mathrm {~g} ^ { - } \mathrm { mol } ^ { - 1 } } \times 4 \times \mathrm { N } _ { \mathrm { A } } \mathrm { mol } ^ { - 1 } = 4 \mathrm {~N} _ { \Lambda }$, and if all 28 g are propylene, then the number of $\frac { 28 \mathrm {~g} } { 42 \mathrm {~g} ^ { \circ } \mathrm { mol } ^ { - 1 } } \times 6 \times \mathrm { N } _ { \mathrm { A } } \mathrm { mol } ^ { - 1 } = 4 \mathrm {~N} _ { \Lambda }$ bonds is $\frac { 28 \mathrm {~g} } { 42 \mathrm {~g} ^ { \circ } \mathrm { mol } ^ { - 1 } } \times 6 \times \mathrm { N } _ { \mathrm { A } } \mathrm { mol } ^ { - 1 } = 4 \mathrm {~N} _ { \Lambda }$. C. If all 28 g are ethylene, the number of C-H bonds is $\frac { 28 \mathrm {~g} } { 42 \mathrm {~g} ^ { \circ } \mathrm { mol } ^ { - 1 } } \times 6 \times \mathrm { N } _ { \mathrm { A } } \mathrm { mol } ^ { - 1 } = 4 \mathrm {~N} _ { \Lambda }$, and C is correct; D. The volume of the solution is not given so it cannot be calculated; D. The volume of the solution is not given so it cannot be calculated.

Question 22: 22. Existing four kinds of solutions at room temperature, the correct description is | No. | $( 1 )...

22. Existing four kinds of solutions at room temperature, the correct description is | No. | $( 1 )$ | $( 2 )$ | $( 3 )$ | $( 4 )$ | :--- | :--- | :--- | :--- | :--- | :--- | | pH | 11 | 11 | 3 | 3 | | solution | ammonia | sodium hydroxide solution | acetate | sulfuric acid | | :--- | :--- | :--- | :--- | :--- | :--- | :--- | .

  • A. A. (3) pH increases and (4) pH remains unchanged after addition of appropriate amount of sodium acetate crystals to each of (3) (4)
  • B. B. Take equal volumes of (3) and (4) solutions respectively and add sufficient amount of zinc grains, the amount of hydrogen produced (3) > (4)
  • C. C. Mixing equal volumes of (1)(2), the ionization equilibrium of $\mathrm { NH } _ { 3 } \cdot \mathrm { H } _ { 2 } \mathrm { O }$ shifts in the reverse direction
  • D. D. Taking equal volumes of (1) and (4) and mixing them, the mixed solution $\mathrm { pH } < 7$

Answer: B

Solution: A. Sodium acetate ionization $\mathrm { CH } _ { 3 } \mathrm { COO } ^ { - }$ inhibits the ionization of acetic acid, sodium acetate and dilute hydrochloric acid reaction to produce a weak electrolyte acetic acid, so (3 (4) were added to the appropriate amount of sodium acetate crystals lead to the solution of $\mathrm { c } \left( \mathrm { H } ^ { + } \right)$ decrease, then the pH of the solution are increased, so the A error; B. Acetic acid is a weak acid, equal pH of the two solutions, the amount of acid concentration (3) > (4), equal volume of the two solutions in the acetic acid can provide more hydrogen ions, add a sufficient amount of zinc grains when the amount of hydrogen produced (3) > (4), so B is correct; C. The pH of solution (1) (2) is the same, then $\mathrm { c } \left( \mathrm { OH } ^ { - } \right)$ is equal, and equal volumes of (1) (2) are mixed, $\mathrm { c } \left( \mathrm { OH } ^ { - } \right)$ remains unchanged, and instantly $\mathrm { c } \left( \mathrm { NH } _ { 4 } ^ { + } \right. ) = \mathrm { c } \left( \mathrm { NH } _ { 3 } \cdot \mathrm { H } _ { 2 } \mathrm { O } \right)$, then $\mathrm { Q } = \frac { \mathrm { c } \left( \mathrm { NH } _ { 4 } ^ { + } \right) \mathrm { c } \left( \mathrm { OH } ^ { - } \right) } { \mathrm { c } \left( \mathrm { NH } _ { 3 } \cdot \mathrm { H } _ { 2 } \mathrm { O } \right) } = \mathrm { K }$, that is 's ionization equilibrium does not move, so C is wrong; D. At room temperature $\mathrm { K } _ { \mathrm { w } } = 1 \times 10 ^ { - 14 }$, if $\mathrm { pH } = 11$ of NaOH solution and $\mathrm { pH } = 3$ of sulfuric acid are mixed in equal volume, $\mathrm { n } \left( \mathrm { H } ^ { + } \right) = \mathrm { n } \left( \mathrm { OH } ^ { - } \right)$, the solution is neutral after mixing, but ammonia monohydrate is a weak base, take an equal volume of ([INLINE_FORMULA_9]] and $\mathrm { n } \left( \mathrm { H } ^ { + } \right) = \mathrm { n } \left( \mathrm { OH } ^ { - } \right)$. 1) and (4) mixed solution pH $> 7$, so D is wrong;

Question 23: 23. If $\mathrm { N } _ { \mathrm { A } }$ represents the value of Avogadro's constant, the followin...

23. If $\mathrm { N } _ { \mathrm { A } }$ represents the value of Avogadro's constant, the following statement is correct

  • A. A. $2 \mathrm {~L} 0.5 \mathrm {~mol} / \mathrm { LHF }$ The number of $\mathrm { H } ^ { + }$ contained in the solution is $\mathrm { N } _ { \mathrm { A } }$
  • B. B. The number of covalent bonds contained in $1 \mathrm { molNH } _ { 4 } \mathrm { Cl }$ is $4 \mathrm {~N} _ { \mathrm { A } }$
  • C. C. The number of ammonia molecules obtained when $22.4 \mathrm { LN } _ { 2 }$ is fully reacted with a sufficient amount of $\mathrm { H } _ { 2 }$ in standard conditions is $2 \mathrm {~N} _ { \mathrm { A } }$
  • D. D. The number of $\mathrm { pH } = 1$ sulfuric acid solutions containing $\mathrm { H } ^ { + }$ is $0.2 \mathrm {~N} _ { \mathrm { A } }$

Answer: B

Solution: A. The amount of HF in the $2 \mathrm {~L} 0.5 \mathrm {~mol} / \mathrm { L } \mathrm { HF }$ solution is 1 mol, HF is a weak electrolyte in electrolytic equilibrium, and the number of $\mathrm { H } ^ { + }$ is less than that of ${ } ^ { \mathrm { N } }$, which is incorrect; B. $1 \mathrm {~mol} \mathrm { NH } _ { 4 } \mathrm { Cl }$ in ${ } ^ { \mathrm { NH } _ { 4 } ^ { + } }$ has three $\mathrm { N } - \mathrm { H }$ covalent bonds, one coordination bond, and a total of four covalent bonds, so the number of covalent bonds is ${ } ^ { 4 \mathrm {~N} _ { \mathrm { A } } }$, and B is correct; C. The reaction between $22.4 \mathrm {~L} \mathrm {~N} _ { 2 }$ and a sufficient amount of $\mathrm { H } _ { 2 }$ under standard conditions is reversible, and the number of ammonia molecules obtained is less than ${ } ^ { 2 \mathrm {~N} _ { \mathrm { A } } }$, which is wrong; D. The end-labeled volume cannot be calculated, D error; Answer choice B.

Question 24: 24. Given $\mathrm { N } _ { \mathrm { A } }$ as the value of Avogadro's constant, the following sta...

24. Given $\mathrm { N } _ { \mathrm { A } }$ as the value of Avogadro's constant, the following statement is correct

  • A. A. At room temperature, the number of hydrogen ions contained in an acetic acid solution of $100 \mathrm {~mL} \mathrm { pH } = 1$ is $0.01 \mathrm {~N} _ { \mathrm { A } }$
  • B. B. A certain amount of sodium reacts with 8 g of oxygen, if there is nothing left of either, the number of electrons transferred is $\mathrm { N } _ { \mathrm { A } }$
  • C. C. Equal quantities of ${ } ^ { 14 } \mathrm { NO }$ and ${ } ^ { 13 } \mathrm { CO }$ gases both contain the number of neutrons in $15 \mathrm {~N} _ { \mathrm { A } }$
  • D. D. 1 mol acrylic acid $\left( \mathrm { CH } _ { 2 } = \mathrm { CHCOOH } \right)$ contains the number of double bonds $\mathrm { N } _ { \mathrm { A } }$

Answer: A

Solution: A. $\mathrm { pH } = 1$ in a solution of acetic acid $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 0.1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 , } 100 \mathrm {~mL}$ The number of hydrogen ions contained in this solution is $0.01 \mathrm {~N} _ { \mathrm { A } }$ and A is correct; B. A certain amount of sodium reacts with 8 g of oxygen and there is nothing left of either, if $\mathrm { Na } _ { 2 } \mathrm { O }$ is formed, the number of electrons transferred is $\mathrm { N } _ { \mathrm { A } }$, if $\mathrm { Na } _ { 2 } \mathrm { O } _ { 2 }$ is formed, the number of electrons transferred is $0.5 \mathrm {~N} _ { \mathrm { A } }$, if $0.5 \mathrm {~N} _ { \mathrm { A } }$ is formed INLINE_FORMULA_6]], and if a mixture of $\mathrm { Na } _ { 2 } \mathrm { O }$ and $\mathrm { Na } _ { 2 } \mathrm { O } _ { 2 }$ is generated, the number of transferred electrons is between $0.5 \mathrm {~N} _ { \mathrm { A } } \sim \mathrm { N } _ { \mathrm { A } }$, which is wrong; C. The specific values of the amounts of the two substances are not specified, so C is incorrect; D. 1 mol of acrylic acid $\left( \mathrm { CH } _ { 2 } = \mathrm { CHCOOH } \right)$ contains $1 \mathrm {~mol} \mathrm { C } = \mathrm { C }$ and $1 \mathrm {~mol} \mathrm { C } = \mathrm { O }$ bonds, so the number of double bonds is $2 \mathrm {~N} _ { \mathrm { A } }$, and D is wrong; The answer is A.

Question 25: 25. Add the same concentration of $10 \mathrm {~mL} 0.01 \mathrm {~mol} / \mathrm { LH } _ { 2 } \ma...

25. Add the same concentration of $10 \mathrm {~mL} 0.01 \mathrm {~mol} / \mathrm { LH } _ { 2 } \mathrm { SO } _ { 4 }$ solution to $\mathrm { BaCl } _ { 2 }$ solution until it is completely precipitated, then the pH of the solution is

  • A. A. 2
  • B. B. 3
  • C. C. 5
  • D. D. 7

Answer: A

Solution: After mixing the two solutions, the solution of ionic reaction $\mathrm { Ba } ^ { 2 + } + \mathrm { SO } _ { 4 } ^ { 2 - } = \mathrm { BaSO } _ { 4 } \downarrow , \mathrm { H } ^ { + }$ does not participate in the reaction, due to the two have the same concentration, so you need to add $\mathrm { BaCl } _ { 2 }$ solution volume of 10 mL, the original $\mathrm { H } _ { 2 } \mathrm { SO } _ { 4 }$ in the $c \left( \mathrm { H } ^ { + } \right) = 0.02 \mathrm {~mol} / \mathrm { L }$ solution, the volume becomes 20 mL, the mixed solution $c \left( \mathrm { H } ^ { + } \right) = 0.01 \mathrm {~mol} / \mathrm { L }$, then the solution $\mathrm { pH } = 2$, so the answer is A, therefore, the answer is A. When the volume of $c \left( \mathrm { H } ^ { + } \right) = 0.01 \mathrm {~mol} / \mathrm { L }$ in the mixed solution becomes 20 mL, the solution $\mathrm { pH } = 2$ is $\mathrm { pH } = 2$.

Question 26: 28. In addition to $\mathrm { H } ^ { + }$, $\mathrm { c } \left( \mathrm { OH } ^ { - } \right)$ is...

28. In addition to $\mathrm { H } ^ { + }$, $\mathrm { c } \left( \mathrm { OH } ^ { - } \right)$ is negligible, $\mathrm { Na } ^ { + } , \mathrm { Cl } ^ { - } , \mathrm { NH } _ { 4 } { } ^ { + } , \mathrm { SO } _ { 4 } { } ^ { 2 - }$ and $\mathrm { Na } ^ { + } , \mathrm { Cl } ^ { - } , \mathrm { NH } _ { 4 } { } ^ { + } , \mathrm { SO } _ { 4 } { } ^ { 2 - }$, the concentrations of which are, in order of prevalence, $\mathrm { c } \left( \mathrm { Na } ^ { + } \right) = 2.3 \times 10 ^ { - 5 } \mathrm {~mol} / \mathrm { L } , \mathrm { c } \left( \mathrm { Cl } ^ { - } \right) = 3.5 \times 10 ^ { - 5 } \mathrm {~mol} / \mathrm { L } , \mathrm { c } \left( \mathrm { NH } _ { 4 } { } ^ { + } \right) = 2.3 \times 10 ^ { - 5 } \mathrm {~mol} / \mathrm { L } , \mathrm { c }$ ([INLINE_FORMULA_4]]) $= 1.05 \times 10 ^ { - 5 } \mathrm {~mol} / \mathrm { L }$, then the pH of the rain is (). $= 1.05 \times 10 ^ { - 5 } \mathrm {~mol} / \mathrm { L }$, then the pH of acid rain at this location is ( )

  • A. A. 3
  • B. B. 4
  • C. C. 5
  • D. D. 6

Answer: C

Solution: Based on the conservation of charge in solution, assuming a hydrogen ion concentration of $x m o l / L$, then ignoring the hydroxide ion concentration there is c $\left( \mathrm { Na } ^ { + } \right) + \mathrm { c } \left( \mathrm { NH } _ { 4 } { } ^ { + } \right) + \mathrm { c } \left( \mathrm { H } ^ { + } \right) = \mathrm { c } \left( \mathrm { Cl } ^ { - } \right) + 2 \mathrm { c } \left( \mathrm { SO } _ { 4 } { } ^ { 2 - } \right) , 2.3 \times 10 ^ { - 5 } + 2.3 \times 10 ^ { - 5 } + \mathrm { x } = 3.5 \times 10 ^ { - }$ ${ } ^ { 5 } + 1.05 \times 10 ^ { - 5 } \times 2$, solving for $\mathrm { x } = 10 ^ { - 5 }$, and therefore $\mathrm { pH } = 5$, and the answer is C.

Question 27: 29. When $25 ^ { \circ } \mathrm { C }$ hydrochloric acid in $100 \mathrm {~mL} 0.4 \mathrm {~mol} /...

29. When $25 ^ { \circ } \mathrm { C }$ hydrochloric acid in $100 \mathrm {~mL} 0.4 \mathrm {~mol} / \mathrm { L }$ is mixed with an equal volume of sodium hydroxide in $0.6 \mathrm {~mol} / \mathrm { L }$, the pH of the solution will be pH value is:

  • A. A. 6
  • B. B. 5
  • C. C. 12
  • D. D. 13

Answer: D

Solution: $25 ^ { \circ } \mathrm { C }$ when $100 \mathrm {~mL} 0.4 \mathrm {~mol} / \mathrm { L }$ hydrochloric acid is mixed with an equal volume of $0.6 \mathrm {~mol} / \mathrm { L }$ sodium hydroxide solution in excess of base. After the reaction, the concentration of hydroxide in the solution is $= \frac { 0.1 \mathrm {~L} \times 0.6 \mathrm {~mol} / \mathrm { L } - 0.1 \mathrm {~L} \times 0.4 \mathrm {~mol} / \mathrm { L } } { 0.2 \mathrm {~L} } = 0.1 \mathrm {~mol} / \mathrm { LL }$, then according to the ion product constant of water, the concentration of hydrogen atoms is $10 ^ { - 13 } \mathrm {~mol} / \mathrm { L }$, and the pH value of the ethanol solution is 13. [点晴]明确反应后氢氧化钠过量首先计算氢氧根浓度是解答的关键,注意掌握 pH计算的一般思维模型: ![](/images/questions/solution-ph/image-004.jpg) $30 . \mathrm { A }$ [Knowledge Points] Conservation of charge between particles in salt solutions, conservation of materials, the principle of conservation of protons, the coexistence of ions under limited conditions, the meaning and composition of solutions [Detailed Explanation]According to the principle of electroneutrality of solutions, $\mathrm { N } \left( \mathrm { Na } ^ { + } \right) + 3 \mathrm {~N} \left( \mathrm { Al } ^ { 3 + } \right) = \mathrm { N } \left( \mathrm { Cl } ^ { - } \right) + 2 \mathrm {~N} \left( { } ^ { \mathrm { SO } _ { 4 } ^ { 2 - } } \right)$, so there is $4 + 3 \times 1 = 1 + 2 \mathrm {~N} \left( \mathrm { SO } _ { 4 } ^ { 2 - } \right)$, and the solution is $\mathrm { N } \left( \mathrm { SO } _ { 4 } ^ { 2 - } \right) = 3$, so the ratio of the number of ions in a solution of $\mathrm { Al } ^ { 3 + }$ and $\mathrm { SO } _ { 4 } ^ { 2 - }$ is $\mathrm { SO } _ { 4 } ^ { 2 - }$. The ratio of the number of ions in the solution is $1 : 3$, so the answer is: A.

Question 28: 30. A solution contains only $\mathrm { Na } ^ { + } , \mathrm { Al } ^ { 3 + } , \mathrm { Cl } ^ {...

30. A solution contains only $\mathrm { Na } ^ { + } , \mathrm { Al } ^ { 3 + } , \mathrm { Cl } ^ { - } , \mathrm { SO } _ { 4 } ^ { 2 - }$ four ions, and the ratio of the first three ions is known to be 4:1: 1, the ratio of the number of ions of $\mathrm { Al } ^ { 3 + }$ and $\mathrm { SO } _ { 4 } ^ { 2 - }$ in the solution is

  • A. A. $1 : 3$
  • B. B. 1: 4
  • C. C. 3: 4
  • D. D. $3 : 2$

Answer: A

Solution:

Question 29: 31. The table shows the solubility of ammonium chloride and potassium nitrate at different temperatu...

31. The table shows the solubility of ammonium chloride and potassium nitrate at different temperatures. The following statements are correct | Temperature/${ } ^ { \circ } \mathrm { C }$ | | 20 | 40 | 50 | 60 | 80 | | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | | Solubility/g | $\mathrm { NH } _ { 4 } \mathrm { Cl }$ | 37.2 | 45.8 | 50.4 | 55.2 | 65.6 | | | $\mathrm { KNO } _ { 3 }$ | 31.6 | 63.9 | 85.5 | 110 | 169 |

  • A. A. $20 ^ { \circ } \mathrm { C }$, the solubility of potassium nitrate is greater than that of ammonium chloride.
  • B. B. $40 ^ { \circ } \mathrm { C }$ when adding 30 g of potassium nitrate to 50 g of water to form a saturated solution
  • C. C. The solute mass fraction of a saturated solution of potassium nitrate at $60 ^ { \circ } \mathrm { C }$ is $50 \%$
  • D. D. A saturated solution of ammonium chloride in $80 ^ { \circ } \mathrm { C }$ was cooled down to $50 ^ { \circ } \mathrm { C }$ and crystals were precipitated.

Answer: D

Solution: A. From the data in the table, the solubility of potassium nitrate is 31.6 g at $20 ^ { \circ } \mathrm { C }$ and that of ammonium chloride is 37.2 g. The solubility of potassium nitrate is less than that of ammonium chloride, so A is wrong; B. At $40 ^ { \circ } \mathrm { C }$, the solubility of potassium nitrate is 63.9 g, and at most 31.95 g of potassium nitrate can be dissolved in 50 g of water at this temperature. Therefore, the saturated solution formed by adding 30 g of potassium nitrate to 50 g of water at this temperature is not a saturated solution of potassium nitrate, and therefore B is wrong; C. At $60 ^ { \circ } \mathrm { C }$, the solubility of potassium nitrate is 110 g, so the mass fraction of solute in a saturated solution of potassium nitrate at this temperature is C. The solubility of potassium nitrate at $\frac { 110 \mathrm {~g} } { 100 \mathrm {~g} + 110 \mathrm {~g} } \times 100 \% \approx 52 \%$ is 110 g, so the mass fraction of solute in the saturated solution of potassium nitrate at this temperature is $\frac { 110 \mathrm {~g} } { 100 \mathrm {~g} + 110 \mathrm {~g} } \times 100 \% \approx 52 \%$; D. The solubility of ammonium chloride at $80 ^ { \circ } \mathrm { C }$ is 50.4 g at $65.6 \mathrm {~g} , ~ 50 ^ { \circ } \mathrm { C }$, that is, the solubility of ammonium chloride decreases with the decrease of temperature, so the saturated solution of ammonium chloride at $80 ^ { \circ } \mathrm { C }$ will be cooled down to $50 ^ { \circ } \mathrm { C }$. FORMULA_7]], crystals precipitate, so D is correct;

Question 30: 32. The pH of a solution of $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 10 ^ { - 10 } \mat...

32. The pH of a solution of $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 10 ^ { - 10 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$, which is ionized from water, is likely to be ().

  • A. A. 10
  • B. B. 4
  • C. C. 10 or 4
  • D. D. 11

Answer: C

Solution: Water ionization of $\mathrm { c } \left( \mathrm { H } ^ { + } \right)$ and water ionization of $\mathrm { c } \left( \mathrm { OH } ^ { - } \right)$ are always equal to $\mathrm { c } \left( \mathrm { OH } ^ { - } \right) _ { \text {水 } } = \mathrm { c } \left( \mathrm { H } ^ { + } \right) _ { \text {水 } } = 1.0 \times 10 ^ { - 10 } \mathrm {~mol} \cdot \mathrm {~L} { } ^ { - 1 }$. Ionization of water is inhibited compared to the ionization of pure water to produce $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 1.0 \times 10 ^ { - 7 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$, where the solute is generally an acid or base. If the solution is an acid, $\mathrm { H } ^ { + }$ is derived from the acid and water, $\mathrm { OH } ^ { - }$ is derived from the water, $\mathrm { c } \left( \mathrm { OH } ^ { - } \right) _ { \text {水 } } = \mathrm { c } \left( \mathrm { OH } ^ { - } \right) = 1.0 \times 10 ^ { - 10 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ and $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 10 ^ { - 4 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 } , \mathrm { pH } = 4$ is present in the solution. ]] comes from water, and $\mathrm { c } \left( \mathrm { H } ^ { + } \right) _ { \text {水 } } = \mathrm { c } \left( \mathrm { H } ^ { + } \right) = 1.0 \times 10 ^ { - 10 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 } , \mathrm { OH } ^ { - }$ comes from the base and water, then $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = 10 ^ { - 10 } \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 } , \mathrm { pH } = 10$, so C is correct. In summary, the answer is C. [点睛] Inhibiting the ionization of water is mainly an acid or a base, or it may be part of a salt, such as sodium bisulfate, and promoting the ionization of water is mainly a salt to be hydrolyzed.

Question 31: 33. Based on the information characterized by the curves in the graphs, the wrong conclusion is draw...

33. Based on the information characterized by the curves in the graphs, the wrong conclusion is drawn. ![](/images/questions/solution-ph/image-005.jpg) Figure 1 ![](/images/questions/solution-ph/image-006.jpg) Figure 2 ![](/images/questions/solution-ph/image-007.jpg) Figure 3 ![](/images/questions/solution-ph/image-008.jpg) Figure 4

  • A. A. Figure 1 shows the pH change curve of adding $0.1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 } \mathrm { CH } _ { 3 } \mathrm { COOH }$ drop by drop to a NaOH solution of volume $10 \mathrm {~mL} 0.1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ at room temperature, then point c has: $\mathrm { c } \left( \mathrm { CH } _ { 3 } \mathrm { COOH } \right) + 2 \mathrm { c } \left( \mathrm { H } ^ { + } \right) = 2 \mathrm { c } \left( \mathrm { OH } ^ { - } \right) + \mathrm { c } \left( \mathrm { CH } _ { 3 } \mathrm { COO } ^ { - } \right)$
  • B. B. In Fig. 2, after mixing $\mathrm { pH } = \mathrm { a }$'s $\mathrm { H } _ { 2 } \mathrm { SO } _ { 4 }$ solution with $\mathrm { pH } = \mathrm { b }$'s NaOH solution in equal volume at the temperature corresponding to the point b, the solution is neutral, then $\mathrm { a } + \mathrm { b } = 12$
  • C. C. From the curve in Fig. 3, $\mathrm { K } _ { \mathrm { sp } } ( \mathrm { AgCl } ) > \mathrm { K } _ { \mathrm { sp } } ( \mathrm { AgBr } ) > \mathrm { K } _ { \mathrm { sp } } ( \mathrm { AgI } )$ can be determined, so when $0.0100 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 } \mathrm { AgNO } _ { 3 }$ standard solution is used to titrate a mixed solution with concentrations of $0.1000 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 } \mathrm { Cl } ^ { - } , \mathrm { Br } ^ { - }$ and $\mathrm { I } ^ { - }$, the first to precipitate is $\mathrm { I } ^ { - }$. FORMULA_4]]
  • D. D. Figure 4 shows the pH change curves of solutions of hydrochloric acid and acetic acid of the same pH when diluted with water, where I denotes hydrochloric acid and II denotes acetic acid, and the conductivity of the solutions: $b > a > c$

Answer: D

Solution: A. Figure 1 shows the pH change curve of adding 0.1 $\mathrm { mol } \cdot \mathrm { L } ^ { - 1 } \mathrm { CH } _ { 3 } \mathrm { COOH }$ drop by drop to a NaOH solution with a volume of $10 \mathrm {~mL} 0.1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ at room temperature, and the amount of acid added at point c is two times that of the base, and there is charge conservation $c \left( \mathrm { Na } ^ { + } \right) + c \left( \mathrm { H } ^ { + } \right) = c \left( \mathrm { OH } ^ { - } \right) + c \left( \mathrm { CH } _ { 3 } \mathrm { COO } ^ { - } \right)$ and material conservation in the solution. $2 c \left( \mathrm { Na } ^ { + } \right) = c \left( \mathrm { CH } _ { 3 } \mathrm { COO } ^ { - } \right) + c \left( \mathrm { CH } _ { 3 } \mathrm { COOH } \right)$, then at point c there is: $c \left( \mathrm { CH } _ { 3 } \mathrm { COOH } \right) + 2 c \left( \mathrm { H } ^ { + } \right) = 2 c \left( \mathrm { OH } ^ { - } \right) + c \left( \mathrm { CH } _ { 3 } \mathrm { COO } ^ { - } \right)$, so A is correct; B. Figure 2 shows the ion product constant of water at the temperature $K _ { w } = c \left( \mathrm { H } ^ { + } \right) \times c \left( \mathrm { OH } ^ { - } \right) = 10 ^ { - 12 }$ for [[INLINE_FORMULA_8] when the $K _ { w } = c \left( \mathrm { H } ^ { + } \right) \times c \left( \mathrm { OH } ^ { - } \right) = 10 ^ { - 12 }$ solution of $\mathrm { pH } = \mathrm { a }$ and $\mathrm { pH } = \mathrm { a }$ solution of $c \left( \mathrm { H } ^ { + } \right) = 10 ^ { - \mathrm { a } } \mathrm { mol } / \mathrm { L } , \mathrm { pH } = \mathrm { b }$ are mixed in the same volume with $c \left( \mathrm { H } ^ { + } \right) = 10 ^ { - \mathrm { a } } \mathrm { mol } / \mathrm { L } , \mathrm { pH } = \mathrm { b }$ of $c \left( \mathrm { H } ^ { + } \right) = 10 ^ { - \mathrm { a } } \mathrm { mol } / \mathrm { L } , \mathrm { pH } = \mathrm { b }$ solution of $c \left( \mathrm { H } ^ { + } \right) = 10 ^ { - \mathrm { a } } \mathrm { mol } / \mathrm { L } , \mathrm { pH } = \mathrm { b }$ at the same temperature. INLINE_FORMULA_9]] of sulfuric acid in $c \left( \mathrm { H } ^ { + } \right) = 10 ^ { - \mathrm { a } } \mathrm { mol } / \mathrm { L } , \mathrm { pH } = \mathrm { b }$ of NaOH solution in $c \left( \mathrm { OH } ^ { - } \right) = \frac { 10 ^ { - 12 } } { 10 ^ { - \mathrm { b } } } = 10 ^ { \mathrm { b } - 12 } \mathrm {~mol} / \mathrm { L }$, the two mixed in equal volume of the solution shows neutral, then the acid and base happen to be completely reacted to form a strong acid and strong base salt of sodium sulfate, i.e., $c \left( \mathrm { H } ^ { + } \right) = 10 ^ { - \mathrm { a } } \mathrm { mol } / \mathrm { L } = c \left( \mathrm { OH } ^ { - } \right) = \frac { 10 ^ { - 12 } } { 10 ^ { - \mathrm { b } } } = 10 ^ { \mathrm { b } - 12 } \mathrm {~mol} / \mathrm { L }$, then $c \left( \mathrm { H } ^ { + } \right) = 10 ^ { - \mathrm { a } } \mathrm { mol } / \mathrm { L } = c \left( \mathrm { OH } ^ { - } \right) = \frac { 10 ^ { - 12 } } { 10 ^ { - \mathrm { b } } } = 10 ^ { \mathrm { b } - 12 } \mathrm {~mol} / \mathrm { L }$, the $c \left( \mathrm { H } ^ { + } \right) = 10 ^ { - \mathrm { a } } \mathrm { mol } / \mathrm { L } = c \left( \mathrm { OH } ^ { - } \right) = \frac { 10 ^ { - 12 } } { 10 ^ { - \mathrm { b } } } = 10 ^ { \mathrm { b } - 12 } \mathrm {~mol} / \mathrm { L }$ is the same as $c \left( \mathrm { H } ^ { + } \right) = 10 ^ { - \mathrm { a } } \mathrm { mol } / \mathrm { L } = c \left( \mathrm { OH } ^ { - } \right) = \frac { 10 ^ { - 12 } } { 10 ^ { - \mathrm { b } } } = 10 ^ { \mathrm { b } - 12 } \mathrm {~mol} / \mathrm { L }$. INLINE_FORMULA_13]], so B is correct; C. In Figure 3, when the values of the horizontal coordinates are equal, the larger the value of the vertical coordinate, the smaller $c \left( \mathrm { X } ^ { - } \right)$ is, and the smaller its solubility product constant is, according to Figure 3, when the horizontal coordinates are the same, $c \left( \mathrm { Cl } ^ { - } \right) > c \left( \mathrm { Br } ^ { - } \right) > c \left( \mathrm { I } ^ { - } \right)$, then $K ( \mathrm { AgCl } ) > K ( \mathrm { AgBr } ) > K ( \mathrm { AgI } )$, and the $0.0100 \mathrm {~mol} / \mathrm { L }$ is used as $0.0100 \mathrm {~mol} / \mathrm { L }$, so B is correct. FORMULA_17]] silver nitrate standard solution, titration of the concentration of both $0.1000 \mathrm {~mol} / \mathrm { LCl } ^ { - } , \mathrm { Br } ^ { - }$ and $\mathrm { I } ^ { - }$ mixed solution, the solubility product constant is small Mr. into the precipitate, so the first precipitation is $\mathrm { I } ^ { - }$, so C is correct; D. pH is the same monohydric acid diluted the same times, pH value change is larger acidic, hydrochloric acid is a strong acid, acetic acid is a weak acid, then pH value of the same hydrochloric acid and acetic acid diluted the same number of times, the pH value of the larger change is hydrochloric acid, so the I said hydrochloric acid, II said acetic acid; the strength of the conductivity of the solution and the concentration of ions proportional to the $c \left( \mathrm { H } ^ { + } \right) : \mathrm { a } > \mathrm { b } > \mathrm { c }$, the solution conductivity: $\mathrm { a } > \mathrm { b } > \mathrm { c }$, so D error;

Question 32: 34 . At room temperature, a $1 \mathrm { LpH } = 3$ solution of $\mathrm { H } _ { 2 } \mathrm { SO ...

34 . At room temperature, a $1 \mathrm { LpH } = 3$ solution of $\mathrm { H } _ { 2 } \mathrm { SO } _ { 4 }$ is mixed with the following solution.

  • A. A. The pH of the solution obtained by mixing with an equal volume of $\mathrm { pH } = 11$ ammonia is less than 7.
  • B. B. The pH of the solution obtained by mixing with $\mathrm { pH } = 3$'s $\mathrm { CH } _ { 3 } \mathrm { COOH }$ solution is less than 3.
  • C. C. The pH of the solution must be less than 7 when mixed with an equal concentration of $\mathrm { CH } _ { 3 } \mathrm { COONa }$ solution.
  • D. D. If the $10 \mathrm {~L} \mathrm { Ba } ( \mathrm { OH } ) _ { 2 }$ solution reacts completely with the $\mathrm { Ba } ( \mathrm { OH } ) _ { 2 }$ solution, then the pH of the $\mathrm { Ba } ( \mathrm { OH } ) _ { 2 }$ solution must be equal to 10

Answer: D

Solution: A. When mixed with an equal volume of $\mathrm { pH } = 11$ ammonia, the ammonia is in excess and the pH of the resulting solution is greater than 7, which is incorrect; B. After mixing with a $\mathrm { pH } = 3$ solution of $\mathrm { CH } _ { 3 } \mathrm { COOH }$, acetic acid is overdosed and the pH of the resulting solution is less than 7, which is wrong; C, equal concentrations of $\mathrm { CH } _ { 3 } \mathrm { COONa }$ solution hydrolyzed alkaline, the two mixed, not necessarily acidic solution. D. The reaction between a strong acid and a strong base is correct.

Question 33: 35. Potassium pertechnetate $\left( \mathrm { K } _ { 2 } \mathrm { FeO } _ { 4 } \right)$ has the f...

35. Potassium pertechnetate $\left( \mathrm { K } _ { 2 } \mathrm { FeO } _ { 4 } \right)$ has the function of sterilizing and disinfecting as well as purifying water, and an experimental group prepares $\mathrm { K } _ { 2 } \mathrm { FeO } _ { 4 }$ under alkaline conditions with the process shown in the figure: ![](/images/questions/solution-ph/image-009.jpg) The following statements are false $$ 3 \mathrm { NaClO } + 2 \mathrm { Fe } \left( \mathrm { NO } _ { 3 } \right) _ { 3 } + 10 \mathrm { NaOH } = 2 \mathrm { Na } _ { 2 } \mathrm { FeO } _ { 4 } + 3 \mathrm { NaCl } + 6 \mathrm { NaNO } _ { 3 } + 5 \mathrm { H } _ { 2 } \mathrm { O } $$

  • A. A. ${ } ^ { 1 } \mathrm {~mol} \mathrm {~K} _ { 2 } \mathrm { FeO } _ { 4 }$ Sterilization capacity equivalent to 1.5 mol HClO
  • B. B. Oxidation reactions:
  • C. C. Sodium pertechnetate is more soluble than potassium pertechnetate at the same temperature
  • D. D. For purification, the glass instruments applied are evaporating dishes, glass rods, beakers, alcohol lamps

Answer: D

Solution: A. 1 mol of hypochlorous acid gets 2 mol of electrons to produce chloride ions, $1 \mathrm {~mol} \mathrm {~K} _ { 2 } \mathrm { FeO } _ { 4 }$ gets 3 mol of electrons to trivalent iron, so ${ } ^ { 1 } \mathrm {~mol} \mathrm {~K} _ { 2 } \mathrm { FeO } _ { 4 }$ has a disinfecting power equivalent to 1.5 mol of HClO, A is correct; B. According to the conservation of gain and loss of electrons and the conservation of elements to match the equation: $3 \mathrm { NaClO } + 2 \mathrm { Fe } \left( \mathrm { NO } _ { 3 } \right) _ { 3 } + 10 \mathrm { NaOH } = 2 \mathrm { Na } _ { 2 } \mathrm { FeO } _ { 4 } + 3 \mathrm { NaCl } + 6 \mathrm { NaNO } _ { 3 } + 5 \mathrm { H } _ { 2 } \mathrm { O }$ , B is correct; C. Flow chart of sodium pertechnetate added to saturated potassium hydroxide solution using the same temperature when the solubility of sodium pertechnetate is greater than potassium pertechnetate can be generated potassium pertechnetate, C is correct; D. purification needs to be filtered, the application of glass instruments are funnels, glass rods, beakers, D error;

Question 34: 36. Two acid solutions of $\mathrm { HClO } _ { 2 }$ of $1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1...

36. Two acid solutions of $\mathrm { HClO } _ { 2 }$ of $1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ and $\mathrm { HMnO } _ { 4 }$ of $1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$, both of which start at $\mathrm { V } _ { 0 }$, are diluted with water at room temperature. Water is added to the two solutions to dilute them, and the resulting curves are shown in the figure. The following statement is correct. ![](/images/questions/solution-ph/image-010.jpg) $\mathrm { HMnO } _ { 4 } < \mathrm { HClO } _ { 2 }$

  • A. A. At $0 \leq \mathrm { pH } \leq 5$, the $\mathrm { HMnO } _ { 4 }$ solution satisfies: $\mathrm { pH } = \mathrm { lg } \frac { \mathrm { V } } { \mathrm { V } _ { 0 } } + \mathrm { l }$
  • B. B. When diluted to pH 3 on both sides, the solution $\mathrm { c } \left( \mathrm { C } _ { 1 \mathrm { O } ^ { 2 } } \right) = \mathrm { c } \left( \mathrm { MnO } ^ { 4 } \right)$
  • C. C. pH of $\mathrm { NaClO } _ { 2 }$ and $\mathrm { NaMnO } _ { 4 }$ solutions at room temperature, both at $0.1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ concentration: $\mathrm { NaMnO } _ { 4 } > \mathrm { NaClO } _ { 2 }$
  • D. D. The volume of NaOH solution consumed was neutralized with NaOH solution of $1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ before dilution, respectively:

Answer: B

Solution: A. According to the graph: because $\mathrm { HMnO } _ { 4 }$ is a strong acid, meet $0 \leq \mathrm { pH } \leq 5$, the pH of the solution and the volume of solution dilution of the relationship $\mathrm { pH } = 1 \mathrm {~g} \frac { \mathrm {~V} } { \mathrm {~V} _ { 0 } } + 1 - 1 = 1 \mathrm {~g} \frac { \mathrm {~V} } { \mathrm {~V} _ { 0 } }$, so A error; B. When diluted to pH 3, according to the law of conservation of materials: $\mathrm { HMnO } _ { 4 }$ solution: $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = \mathrm { c } \left( \mathrm { MnO } ^ { 4 } \right) + \mathrm { c } \left( \mathrm { OH } ^ { - } \right)$; $\mathrm { HClO } _ { 2 }$ solution: $\mathrm { c } \left( \mathrm { H } ^ { + } \right) = \mathrm { c } \left( \mathrm { ClO } ^ { - } \right) + \mathrm { c } \left( \mathrm { OH } ^ { - } \right)$, when the pH is 3 $\mathrm { c } \left( \mathrm { ClO } ^ { - } \right) = \mathrm { c } \left( \mathrm { MnO } ^ { - } \right)$, when the pH is 3 $0 \leq \mathrm { pH } \leq 5$, solution pH and volume dilution relationship $\mathrm { pH } = 1 \mathrm {~g} \frac { \mathrm {~V} } { \mathrm {~V} _ { 0 } } + 1 - 1 = 1 \mathrm {~g} \frac { \mathrm {~V} } { \mathrm {~V} _ { 0 } }$, so A is wrong. FORMULA_7]], so B is correct; C. From the figure, we can see that the acidity: $\mathrm { HClO } _ { 2 } < \mathrm { HMnO } _ { 4 }$, the weaker the acid, the greater the degree of hydrolysis of acid ions, the concentration of $0.1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ of the $\mathrm { NaClO } _ { 2 }$ and $\mathrm { NaMnO } _ { 4 }$ pH: $\mathrm { NaMnO } _ { 4 } < \mathrm { NaClO } _ { 2 }$, so B is correct. FORMULA_12]], so C is wrong; D. Both are mono acids and have the same amount of substance, so they are neutralized with $1 \mathrm {~mol} \cdot \mathrm {~L} ^ { - 1 }$ NaOH solution before dilution, and the volume of NaOH solution consumed should be equal, so D is wrong; Therefore, the answer is: B

Question 35: 37 . At room temperature, the following description of a dilute solution of acetic acid is correct

37 . At room temperature, the following description of a dilute solution of acetic acid is correct

  • A. A. Dilute the acetic acid in $\mathrm { pH } = \mathrm { a }$ to $\mathrm { pH } = \mathrm { a } + 1$, and the concentration of acetic acid becomes $\frac { 1 } { 10 }$.
  • B. B. During the process of diluting the acetic acid of $\mathrm { pH } = \mathrm { a }$ to $\mathrm { pH } = \mathrm { a } + 1$, $\frac { c \left( \mathrm { CH } _ { 3 } \mathrm { COOH } \right) } { c \left( \mathrm { H } ^ { + } \right) }$ becomes smaller.
  • C. C. $\mathrm { pH } = \mathrm { a }$ of acetic acid and $\mathrm { pH } = \mathrm { a } + 1$ of acetic acid are neutralized with equal amounts of NaOH solution, and the ratio of the volume consumed by both is $1 : 10$
  • D. D. When an equal volume of $\mathrm { pH } = \mathrm { a }$ acetic acid is exactly neutralized with $\mathrm { pH } = \mathrm { b }$ NaOH solution, there is $\mathrm { a } + \mathrm { b } = 14$

Answer: B

Solution: A. Dilute $\mathrm { pH } = \mathrm { a }$ of acetic acid to $\mathrm { pH } = \mathrm { a } + 1 , ~ c \left( \mathrm { H } ^ { + } \right)$ to $\frac { 1 } { 10 }$, and since the ionization of acetic acid increases after dilution, the concentration of acetic acid is smaller than that of the original $\frac { 1 } { 10 }$, A is incorrect; B. In the process of diluting $\mathrm { pH } = \mathrm { a }$ to $\mathrm { pH } = \mathrm { a } + 1$, $n \left( \mathrm { CH } _ { 3 } \mathrm { COOH } \right)$ decreases, $n \left( \mathrm { H } ^ { + } \right)$ increases, and $\mathrm { pH } = \mathrm { a }$ decreases. $$ \frac { c \left( \mathrm { CH } _ { 3 } \mathrm { COOH } \right) } { c \left( \mathrm { H } ^ { + } \right) } = \frac { n \left( \mathrm { CH } _ { 3 } \mathrm { COOH } \right) } { n \left( \mathrm { H } ^ { + } \right) } \text {decreases, B is correct; } $$ C. $\mathrm { pH } = \mathrm { a }$ of acetic acid and $\mathrm { pH } = \mathrm { a } + 1$ of acetic acid, because the smaller the concentration of acetic acid, the greater the degree of ionization, so the former concentration of acetic acid than the latter 10 times larger than the concentration of acetic acid, respectively, and an equal amount of NaOH solution, and the ratio of the two consumed by the volume is less than $1 : 10$, C incorrect; C incorrect; C incorrect; C incorrect; C incorrect; C incorrect; C incorrect; C incorrect; C incorrect; C incorrect. 11]], C is incorrect; D. $\mathrm { pH } = \mathrm { a }$ of acetic acid, whose concentration is greater than that of $10 ^ { - \mathrm { a } } \mathrm { mol } / \mathrm { L } , \mathrm { pH } = \mathrm { b }$ of NaOH solution, whose concentration is $10 ^ { - ( 14 - \mathrm { b } ) }$, and when exactly equal volumes are neutralized, there is $\left( > 10 ^ { - a } \right) = 10 ^ { - ( 14 - b ) }$, and $10 ^ { - a } < 10 ^ { - ( 14 - b ) } , ~ a > 14 - b , ~ a + b > 14 , ~ D$ is $10 ^ { - a } < 10 ^ { - ( 14 - b ) } , ~ a > 14 - b , ~ a + b > 14 , ~ D$. FORMULA_16]] is incorrect;

Question 36: 38. There are three equal portions of caustic soda solution. The first portion reacts directly with ...

38. There are three equal portions of caustic soda solution. The first portion reacts directly with hydrochloric acid; the second portion is doubled and then reacted with hydrochloric acid; and the third portion reacts with hydrochloric acid after the appropriate amount of $\mathrm { CO } _ { 2 }$ is passed through it. If the concentration of hydrochloric acid is the same, and the volumes of hydrochloric acid consumed in the complete reaction are $V _ { 1 } , V _ { 2 }$ and $V _ { 3 }$, then the correct relationship between the size of $V _ { 1 } , V _ { 2 }$ and $V _ { 3 }$ is

  • A. A. $V _ { 1 } = V _ { 2 } = V _ { 3 }$
  • B. B. $\mathrm { V } _ { 1 } > \mathrm { V } _ { 3 } > \mathrm { V } _ { 2 }$
  • C. C. $\mathrm { V } _ { 2 } > \mathrm { V } _ { 3 } > \mathrm { V } _ { 1 }$
  • D. D. $\mathrm { V } _ { 1 } > \mathrm { V } _ { 2 } > \mathrm { V } _ { 3 }$

Answer: A

Solution: The final product is NaCl, according to the conservation of Na and Cl atoms: $\mathrm { n } ( \mathrm { HCl } ) = \mathrm { n } ( \mathrm { NaCl } ) = n ~ ( \mathrm { NaOH } ) ~ , ~$ Since the amount of NaOH is equal, the amount of HCl consumed is equal, so the volume of hydrochloric acid consumed is equal, i.e. $V _ { 1 } = V _ { 2 } = V _ { 3 }$. The answer is A. [Points clear] The question focuses on the examination of analytical ability and calculation ability, the difficulty of the question is not big, pay attention to the calculation according to the conservation of elemental mass, can save the middle process of the tedious.
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Solution Concentration and pH

溶液浓度与pH

36 Practice Questions

Practice with Chinese questions to prepare for the CSCA exam. You can toggle translations while practicing.

Topic Overview

The knowledge point covers the calculation of the relationship between the concentration of the solution (such as molar concentration, mass fraction) and pH, focusing on the calculation of pH of strong acid/base and weak acid/base solutions, as well as the pattern of change of pH in the process of dilution, mixing and titration. In the examination is often combined with solubility curves, neutralization reaction images for comprehensive examination, need to be flexible use of formulas and understanding of acid-base equilibrium principle.

Questions:36

Key Points

  • 1Direct calculation of pH of strong acid/base solutions with dilution laws
  • 2Ionization equilibrium and pH approximation for weak acids/bases
  • 3pH changes and indicator selection during acid-base neutralization titrations
  • 4Tips for determining and calculating pH after mixing solutions

Study Tips

It is recommended that you master the pH calculations for different acid-base types through categorization exercises and become proficient in using the core formulas pH = -lg[H⁺] and Kw = [H⁺][OH-].

Practicing topics ≠ Passing the exam

Full mock exam based on official syllabus, with mixed topics like the real test