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Grade 12 Chemistry: formula sheet

Energy, rates, equilibrium, acids, cells and solutions · 58 formulas · metric edition 1

The full study guide: modules, problems, answer key
Module 1 · Thermochemistry
Chemistry 12-1 Moles from Mass (n = m/M)
n=mMn = \frac{m}{M}
Converts a measured mass into an amount of substance by dividing by the molar mass.
Chemistry 12-2 Particles from Moles (Avogadro's Number)
N=n NAN = n\,N_A
Converts an amount in moles into an actual particle count using the Avogadro constant NA =…
Chemistry 12-3 Sensible Heat (Q = mcΔT)
Q=mcΔTQ = m c \Delta T
Heat needed to change a mass's temperature: mass times specific heat times the temperature change.
Chemistry 12-4 Latent Heat
Q=mLQ = m L
Heat absorbed or released when a mass changes phase at constant temperature.
Chemistry 12-5 Heat of Reaction
q=nΔHq = n \Delta H
Scales a reaction's molar enthalpy change by the amount reacted to give the total heat released or…
Chemistry 12-6 Molarity (C = n/V)
C=nVC = \frac{n}{V}
Defines molar concentration as moles of solute per volume of solution.
Chemistry 12-7 Hess's Law (Three-Step Sum)
ΔHrxn=ΔH1+ΔH2+ΔH3\Delta H_{\text{rxn}} = \Delta H_1 + \Delta H_2 + \Delta H_3
Hess's law: the enthalpy change of a target reaction is the sum of the enthalpy changes of the…
Chemistry 12-8 Standard Enthalpy of Reaction from Formation Enthalpies
ΔHrxn∘=∑ΔHf,prod∘−∑ΔHf,react∘\Delta H^{\circ}_{\text{rxn}} = \sum \Delta H^{\circ}_{f,\text{prod}} - \sum \Delta H^{\circ}_{f,\text{react}}
The tabulated form of Hess's law: standard enthalpy of reaction equals the summed formation…
Module 2 · Rates & Kinetics
Chemistry 12-9 Power-Law Reaction Rate
r=k CA nr = k\,C_A^{\,n}
The rate of a reaction as a power of the reactant concentration.
Chemistry 12-10 Arrhenius Equation
k=A e−Ea/RTk = A\,e^{-E_a/RT}
Gives a reaction's rate constant from its activation energy, pre-exponential factor, and absolute…
Chemistry 12-11 Arrhenius Two-Temperature Form
ln⁡k2k1=EaR(1T1−1T2)\ln\frac{k_2}{k_1} = \frac{E_a}{R}\left(\frac{1}{T_1} - \frac{1}{T_2}\right)
Extracts an activation energy from two rate constants measured at two temperatures, eliminating the…
Chemistry 12-12 Activation Energy from an Arrhenius Plot
Ea=−R×slopeE_a = -R \times \text{slope}
Converts the slope of a ln k versus 1/T Arrhenius plot into an activation energy, the standard…
Chemistry 12-13 Zero-Order Integrated Rate Law
[A]=[A]0−kt[\mathrm{A}] = [\mathrm{A}]_0 - kt
Gives the concentration remaining in a zero-order reaction, where the rate is constant and…
Chemistry 12-14 First-Order Integrated Rate Law
[A]=[A]0 e−kt[\mathrm{A}] = [\mathrm{A}]_0\,e^{-kt}
Gives the concentration remaining in a first-order reaction, the exponential decay that governs…
Chemistry 12-15 Half-Life Decay
N=N0(12)t/t1/2N = N_0 \left(\frac{1}{2}\right)^{t/t_{1/2}}
Gives the quantity remaining after repeated halvings over an elapsed time measured in half-lives.
Chemistry 12-16 Half-Life and Decay Constant
t1/2=ln⁡2λt_{1/2} = \frac{\ln 2}{\lambda}
Converts between a half-life and the exponential decay constant via the factor ln 2 = 0.6931471806.
Chemistry 12-17 Second-Order Integrated Rate Law
1[A]=1[A]0+kt\frac{1}{[\mathrm{A}]} = \frac{1}{[\mathrm{A}]_0} + kt
Gives the concentration remaining in a second-order reaction, where the reciprocal of concentration…
Chemistry 12-18 Half-Life of a Second-Order Reaction
t1/2=1k [A]0t_{1/2} = \frac{1}{k\,[\mathrm{A}]_0}
Gives the half-life of a second-order reaction, which unlike a first-order half-life depends on the…
Module 3 · Chemical Equilibrium
Chemistry 12-19 Equilibrium Constant Kc (A + B ⇌ C + D)
Kc=[C][D][A][B]K_c = \frac{[\mathrm{C}][\mathrm{D}]}{[\mathrm{A}][\mathrm{B}]}
Computes the equilibrium constant or reaction quotient for a one-to-one reaction from the four…
Chemistry 12-20 Reaction Quotient Q (aA + bB ⇌ cC)
Q=[C]c[A]a [B]bQ = \frac{[\mathrm{C}]^{c}}{[\mathrm{A}]^{a}\,[\mathrm{B}]^{b}}
Reaction quotient Q from any concentrations, raised to stoichiometric powers: the number you…
Chemistry 12-21 Kp from Kc (Kp = Kc(RT)^Δn)
Kp=Kc(RT)ΔnK_p = K_c (RT)^{\Delta n}
Converts a gas-phase equilibrium constant between pressure and concentration bases using the change…
Chemistry 12-22 Ideal Gas Law
PV=nRTP V = n R T
Relates pressure, volume, amount, and temperature of a gas.
Chemistry 12-23 Solubility Product of a 1:1 Salt
Ksp=s2K_{sp} = s^{2}
Links the solubility product of an AB salt such as AgCl or BaSO4 to its molar solubility, since…
Chemistry 12-24 Solubility Product of an AB₂ Salt
Ksp=4s3K_{sp} = 4s^{3}
Links the solubility product of an AB2 or A2B salt such as CaF2 or Mg(OH)2 to its molar solubility,…
Chemistry 12-25 Gibbs Free Energy Change (ΔG = ΔH − TΔS)
ΔG=ΔH−T ΔS\Delta G = \Delta H - T\,\Delta S
Combines a reaction's enthalpy and entropy changes at a given temperature to decide whether it can…
Chemistry 12-26 Gibbs Free Energy and the Equilibrium Constant
ΔG∘=−RTln⁡K\Delta G^{\circ} = -RT\ln K
Converts between a reaction's standard free energy change and its equilibrium constant, the bridge…
Module 4 · Acids & Bases
Chemistry 12-27 pH from Hydrogen Ion Concentration
pH=−log⁡10 [H+]\mathrm{pH} = -\log_{10}\,[\mathrm{H^+}]
Expresses acidity as the negative base-10 logarithm of the hydrogen ion concentration in mol/L.
Chemistry 12-28 pH and pOH Relation
pH+pOH=14\mathrm{pH} + \mathrm{pOH} = 14
Links the acidity and basicity scales of any aqueous solution at 25 °C, where pKw = 14.
Chemistry 12-29 Ka and Kb Relation through Kw
Ka Kb=KwK_a \, K_b = K_w
Links a weak acid's dissociation constant to that of its conjugate base through the ion product of…
Chemistry 12-30 pKa from Acid Dissociation Constant
pKa=−log⁡10Ka\mathrm{p}K_a = -\log_{10} K_a
Converts an acid dissociation constant into its logarithmic pKa form and back, compressing a huge…
Chemistry 12-31 pKb from Base Dissociation Constant
pKb=−log⁡10Kb\mathrm{p}K_b = -\log_{10} K_b
Converts a base dissociation constant into its logarithmic pKb form and back, the basic-side…
Chemistry 12-32 pH of a Weak Acid from Ka
pH=−log⁡10Ka C\mathrm{pH} = -\log_{10}\sqrt{K_a\,C}
Estimates the pH of a weak monoprotic acid solution from its dissociation constant and formal…
Chemistry 12-33 Percent Ionization of a Weak Acid
% ion=[H+]C×100%\%\,\text{ion} = \frac{[\mathrm{H^+}]}{C} \times 100\%
Expresses what fraction of a weak acid has actually donated its proton, comparing the equilibrium…
Chemistry 12-34 Henderson–Hasselbalch Equation (Weak Acid Buffer)
pH=pKa+log⁡10 ⁣[A−][HA]\mathrm{pH} = \mathrm{p}K_a + \log_{10}\!\frac{[\mathrm{A^-}]}{[\mathrm{HA}]}
Gives the pH of a buffer from the acid's pKa and the ratio of conjugate base to undissociated acid,…
Chemistry 12-35 Henderson–Hasselbalch Equation (Weak Base Buffer)
pOH=pKb+log⁡10 ⁣[BH+][B]\mathrm{pOH} = \mathrm{p}K_b + \log_{10}\!\frac{[\mathrm{BH^+}]}{[\mathrm{B}]}
Gives the pOH of a weak base buffer from the base's pKb and the ratio of conjugate acid to free…
Chemistry 12-36 Dilution Equation (C1V1 = C2V2)
C1V1=C2V2C_1 V_1 = C_2 V_2
States that concentration times volume is conserved when a solution is diluted, since the moles of…
Chemistry 12-37 Titration: Concentration of an Unknown
Ca=n CbVbVaC_a = \frac{n\,C_b V_b}{V_a}
Finds an analyte's concentration from the titre volume, titrant concentration, and the reaction's…
Module 5 · Electrochemistry
Chemistry 12-38 Standard Cell Potential from Half-Cells
Ecell∘=Ecathode∘−Eanode∘E^{\circ}_{\text{cell}} = E^{\circ}_{\text{cathode}} - E^{\circ}_{\text{anode}}
Builds a galvanic cell's standard voltage by subtracting the anode's standard reduction potential…
Chemistry 12-39 Nernst Equation
E=E∘−RTnFln⁡QE = E^{\circ} - \frac{RT}{nF}\ln Q
Corrects a cell's standard potential for non-standard concentrations, the equation behind every pH…
Chemistry 12-40 Electric Charge (Q = It)
Q=ItQ = I t
Total charge transferred by a steady current flowing for a given time.
Chemistry 12-41 Faraday's Law of Electrolysis (m = QM/nF)
m=QMnFm = \frac{Q M}{n F}
Faraday's law of electrolysis: the mass plated out at an electrode from the charge passed, the…
Module 6 · Gases & Solutions
Chemistry 12-42 Boyle's Law
P1V1=P2V2P_1 V_1 = P_2 V_2
At constant temperature, pressure times volume stays constant for a fixed amount of gas.
Chemistry 12-43 Charles's Law
V1T1=V2T2\frac{V_1}{T_1} = \frac{V_2}{T_2}
At constant pressure, gas volume is directly proportional to absolute temperature.
Chemistry 12-44 Gay-Lussac's Law
P1T1=P2T2\frac{P_1}{T_1} = \frac{P_2}{T_2}
At constant volume, gas pressure is directly proportional to absolute temperature.
Chemistry 12-45 Combined Gas Law
P1V1T1=P2V2T2\frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2}
For a fixed amount of gas, pressure times volume over absolute temperature stays constant between…
Chemistry 12-46 Gas Volume at STP
V=n VmV = n\,V_m
Converts between moles of an ideal gas and its volume at STP using the molar volume Vm = 22.414…
Chemistry 12-47 Gas Density from Molar Mass
ρ=PMRT\rho = \frac{PM}{RT}
Gives an ideal gas's density from its molar mass, pressure, and absolute temperature using R =…
Chemistry 12-48 Partial Pressure from Mole Fraction
Pi=xi PtotalP_i = x_i \, P_{\text{total}}
Gives a gas component's partial pressure as its mole fraction times the total pressure, the…
Chemistry 12-49 Mole Fraction
x1=n1n1+n2x_1 = \frac{n_1}{n_1 + n_2}
Gives the fraction of all moles in a two-component mixture contributed by the solute.
Chemistry 12-50 Graham's Law of Effusion
r1r2=M2M1\frac{r_1}{r_2} = \sqrt{\frac{M_2}{M_1}}
Relates the effusion rates of two gases to the inverse square root of their molar masses.
Chemistry 12-51 Molality (b = n/m)
b=nmsolventb = \frac{n}{m_{\text{solvent}}}
Defines molality as moles of solute per kilogram of solvent.
Chemistry 12-52 Mass Percent of a Solution
c=msolutemsolution×100%c = \frac{m_{\text{solute}}}{m_{\text{solution}}} \times 100\%
Expresses a solution's concentration as the solute's share of the total solution mass in percent.
Chemistry 12-53 Boiling-Point Elevation
ΔTb=Kb b\Delta T_b = K_b \, b
Gives how far a dissolved solute raises a solvent's boiling point from the molality and the…
Chemistry 12-54 Freezing-Point Depression
ΔTf=Kf b\Delta T_f = K_f \, b
Gives how far a dissolved solute lowers a solvent's freezing point from the molality and the…
Chemistry 12-55 Osmotic Pressure (Π = MRT)
Π=MRT\Pi = M R T
Gives the osmotic pressure of a dilute solution from its molar concentration and absolute…
Chemistry 12-56 Raoult's Law
P=x P0P = x \, P^{0}
Gives the vapour pressure of a solvent above an ideal solution as its mole fraction times the pure…
Chemistry 12-57 Henry's Law (Gas Solubility)
C=H PC = H\,P
At a fixed temperature the concentration a gas reaches in a liquid is proportional to its partial…
Chemistry 12-58 Clausius–Clapeyron Equation (Two-Point Form)
ln⁡ ⁣(P2P1)=−ΔHvapR(1T2−1T1)\ln\!\left(\frac{P_2}{P_1}\right) = -\frac{\Delta H_{vap}}{R}\left(\frac{1}{T_2} - \frac{1}{T_1}\right)
Relates two points on a liquid's vapour-pressure curve to its molar enthalpy of vaporisation,…