Chemistry Formula Reference

Formula reference for CSCA preparation

Basic Concepts

Name	Formula	Unit
Amount of substance	$n = \frac{N}{N_A}$	mol
Molar mass	$M = \frac{m}{n}$	g/mol
Avogadro constant	$N_A = 6.02 \times 10^{23}$	/mol
Molar concentration	$c = \frac{n}{V}$ Applies when: V is the volume of the solution, not of the solvent; units mol/L How the real exam asks it	mol/L
Molar volume (STP)	$V_m = 22.4 \text{ L/mol}$ Applies when: Gases only; the molar volume is 22.4 L/mol at STP (0 °C, 101 kPa) — that value does not carry over to other conditions How the real exam asks it	L/mol
Mass fraction	$w = \frac{m_{\text{solute}}}{m_{\text{solution}}} \times 100\%$ Applies when: The denominator is the mass of the solution (solute plus solvent), not of the solvent How the real exam asks it	%
Density	$\rho = \frac{m}{V}$	g/mL
Ideal gas law	$PV = nRT$	-
Dilution formula	$c_1 V_1 = c_2 V_2$ Applies when: The amount of solute is unchanged by dilution; valid only when diluting, not reacting How the real exam asks it	-

Stoichiometry

Name	Formula	Unit
Conservation of mass	$m_{\text{reactants}} = m_{\text{products}}$	-
Gas density (STP)	$\rho = \frac{M}{22.4}$	g/L
Average molar mass	$\bar{M} = \frac{\sum n_i M_i}{\sum n_i}$	g/mol
Theoretical yield	$\text{Yield} = \frac{\text{actual}}{\text{theoretical}} \times 100\%$	%

Thermochemistry

Name	Formula	Unit
Enthalpy change	$\Delta H = H_{\text{products}} - H_{\text{reactants}}$	kJ/mol
Hess's Law	$\Delta H_{\text{total}} = \Delta H_1 + \Delta H_2 + \cdots$	kJ/mol
Heat of combustion	$Q = n \cdot \Delta H_c$	kJ
Heat of neutralization	$\Delta H \approx -57.3 \text{ kJ/mol}$	kJ/mol
Bond energy and enthalpy	$\Delta H = \sum E_{\text{broken}} - \sum E_{\text{formed}}$	kJ/mol

Chemical Equilibrium

Name	Formula	Unit
Equilibrium constant (Kc)	$K_c = \frac{[C]^c [D]^d}{[A]^a [B]^b}$	-
Pressure constant (Kp)	$K_p = \frac{p_C^c \cdot p_D^d}{p_A^a \cdot p_B^b}$	-
Reaction quotient	$Q < K \Rightarrow \text{forward},\; Q > K \Rightarrow \text{reverse},\; Q = K \Rightarrow \text{equilibrium}$	-
Conversion rate	$\alpha = \frac{n_0 - n}{n_0} \times 100\%$	%

Chemical Kinetics

Name	Formula	Unit
Reaction rate	$v = \frac{\Delta c}{\Delta t}$ Applies when: An average rate over the interval, always positive; rates quoted for different species are in the ratio of their stoichiometric coefficients How the real exam asks it	mol/(L*s)
Rate law	$v = k[A]^m [B]^n$	-
Arrhenius equation	$k = A e^{-E_a / RT}$	-
Half-life (1st order)	$t_{1/2} = \frac{\ln 2}{k}$	s

Electrochemistry

Name	Formula	Unit
Faraday constant	$F = 96500 \text{ C/mol}$	C/mol
Electrolysis mass	$m = \frac{M I t}{n F}$	g
Cell EMF	$E = E^{+} - E^{-}$	V
Nernst equation	$E = E^\circ - \frac{RT}{nF} \ln Q$	V

Acid-Base Equilibrium

Name	Formula	Unit
pH definition	$pH = -\lg [H^+]$	-
pOH definition	$pOH = -\lg [OH^-]$	-
Ion product of water	$K_w = [H^+][OH^-] = 10^{-14}$ Applies when: The ionic product is 1×10⁻¹⁴ at 25 °C; it varies with temperature only — adding acid or base does not change it How the real exam asks it	-
pH + pOH	$pH + pOH = 14 \quad (25^\circ C)$	-
Acid dissociation	$K_a = \frac{[H^+][A^-]}{[HA]}$	-
Buffer equation	$pH = pK_a + \lg \frac{[A^-]}{[HA]}$	-

Solubility Equilibrium

Name	Formula	Unit
Solubility product	$K_{sp} = [M^+]^m [A^-]^n$	-
Solubility	$s = \sqrt[n]{K_{sp}}$	mol/L
Precipitation condition	$Q_{sp} > K_{sp} \Rightarrow \text{precipitate forms}$	-

Interactive Simulations

Deepen your understanding through visual animations

Acid-Base Neutralization Visualization

Simulate HCl and NaOH neutralization. Observe pH changes and ion bonding process.

HCl + NaOH \rightarrow NaCl + H_2OpH = -\log[H^+]

5 minBasicInteractive

Mole Calculation Interactive Tool

Select a substance and convert between mass, moles, particle count, and gas volume. Understand the mole concept.

n = \frac{m}{M}n = \frac{N}{N_A}

5 minBeginnerInteractive

Matter Classification Interactive Exercise

Drag substances to the correct category. Master classification of pure substances, mixtures, elements, and compounds.

5 minBeginnerInteractive

Chemical Nomenclature Interactive Quiz

Practice converting between chemical formulas and names. Covers oxides, acids, bases, and salts.

5 minBeginnerInteractive

Reaction Rate Interactive Simulation

Concentration-time curves with particle collision animation. Adjust temperature and catalyst to observe rate changes.

v = -\frac{\Delta[A]}{\Delta t}k = Ae^{-E_a/(RT)}

5 minBasicInteractive

Redox Reactions & Galvanic Cell Simulation

Galvanic cell animation showing electron flow, ion migration, and electrode potential. Understand redox reactions.

E_{cell} = E_{cathode}^\circ - E_{anode}^\circ

5 minBasicInteractive

Solution pH Interactive Simulation

Acid-base titration simulation with real-time pH curve and solution color changes.

pH = -\log[H^+]K_w = [H^+][OH^-] = 10^{-14}

5 minBasicInteractive

Atomic Structure & Periodic Law Interactive Demo

Interactive periodic table showing electron configurations and periodic trends (atomic radius, ionization energy, electronegativity).

E_n = -13.6\frac{Z^2}{n^2}\text{ eV}

5 minBasicInteractive

Chemical Bonding & Molecular Structure Interactive Demo

Compare ionic, covalent, and metallic bonds. Lewis structure visualization. Understand molecular polarity.

\Delta EN = |EN_A - EN_B|

5 minBasicInteractive

Ionic Reactions Interactive Demo

Demonstrate conversion from molecular to ionic equations. Identify spectator ions and net ionic equations.

Ag^+ + Cl^- \rightarrow AgCl\downarrow

5 minBasicInteractive

Organic Chemistry Interactive Demo

Hydrocarbon molecular structures, functional group identification, and isomer counting.

C_nH_{2n+2}C_nH_{2n}

5 minBasicInteractive

Ready to Practice?

Apply these formulas through practice questions