Mole Relationships
n moles, m mass (g), M molar mass (g mol⁻¹).
n = m / M n = c V (for solutions; V in dm³) IB Diploma Programme 2026
⚗️ IBDP Chemistry Formula Sheet
Mole ratios, energy cycles, reaction rates, equilibrium, acids, electrochemistry, and HL Gibbs/Arrhenius equations in one place.
Stoichiometry Kinetics HL Thermodynamics
Balance Equations & Concepts
IB Chemistry rewards clear variable labelling and consistent units. This sheet is split into SL cores plus HL-only thermodynamic and rate expressions.
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Step-by-step stoichiometry
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Energy cycle reminders
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Electrochemistry overview
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HL Gibbs & Arrhenius
Stoichiometry & Solutions (SL Core)
Mole calculations, gas relationships, and yield analysis forming the backbone of Section A short answers.
Ideal Gas Law
p pressure (Pa), V volume (m³), n moles, R 8.31 J mol⁻¹ K⁻¹, T temperature (K).
pV = nRT Percentage Yield
Actual mass vs theoretical mass from stoichiometry.
% Yield = (Actual / Theoretical) × 100% Topic Focus
Mole Pathways
- Map out conversion chains (mass → moles → ratio → product mass) before calculating.
- Indicate state symbols or gas molar volume if working under room conditions.
Gas Law Context
- Specify units (Pa, m³, K) to avoid inconsistent substitutions in pV = nRT.
- Discuss real vs. ideal gas assumptions when prompted.
Percentage Yield/Purity
- Differentiate between yield (actual vs. theoretical) and purity (desired compound fraction).
- Include reason for less-than-100% yield (reversible reaction, loss during transfer) in explanations.
Energetics & Equilibrium (SL Core)
Calorimetry, Hess cycles, and equilibrium reasoning relevant to both Paper 1 MCQs and Paper 2 data response.
Enthalpy Change
ΔH enthalpy change, m mass, c specific heat, ΔT temperature change.
q = m c ΔT (then ΔH = q / n) Hess' Law
Sum enthalpy changes of multiple steps to obtain target reaction.
ΔH°_reaction = Σ ΔH°_products − Σ ΔH°_reactants Equilibrium Constant
Products raised to stoichiometric coefficients over reactants.
K_c = Π [products]^{coeff} / Π [reactants]^{coeff} Reaction Quotient
Same expression as K but with non-equilibrium concentrations.
Q_c = Π [products]_current^{coeff} / Π [reactants]_current^{coeff} Topic Focus
Calorimetry Steps
- Write q = mcΔT with sign and then divide by moles to reach molar enthalpy change.
- Mention experimental sources of error such as heat loss to surroundings.
Hess Cycle Logic
- Indicate direction of arrows and sign changes when summing enthalpy pathways.
- Reference standard states (298 K, 1 bar) if values assume standard enthalpies.
Equilibrium Reasoning
- State expression for K_c before substituting concentrations to avoid algebra slips.
- Discuss whether Q < K (forward shift) or Q > K (reverse shift) when analyzing disturbances.
Acids, Bases & Electrochemistry (SL Core)
pH/pOH, Ka expressions, and electrochemical relationships essential for Paper 2 calculations and IA commentary.
pH and pOH
[H⁺] hydrogen ion concentration (mol dm⁻³).
pH = −log₁₀[H⁺] pOH = −log₁₀[OH⁻] pH + pOH = 14 at 298 K Ka and pKa
Weak acid HA dissociating into H⁺ and A⁻.
K_a = [H⁺][A⁻] / [HA] pK_a = −log₁₀ K_a Nernst Equation (cell potential)
E cell potential, E° standard potential, n electrons transferred, Q reaction quotient, F Faraday constant, R gas constant, T Kelvin.
E = E° − (RT / nF) ln Q Topic Focus
pH Language
- Clarify whether concentration is equilibrium [H⁺] or initial value when using pH = −log[H⁺].
- Reference significant figures for logarithmic answers (digits after decimal equal sig figs in concentration).
Weak Acids/Buffers
- State assumptions (e.g., [HA] ≈ initial) before simplifying Ka expressions.
- Use Henderson-Hasselbalch form when buffer components both present.
Electrochemistry
- Mention that E° values correspond to reduction potentials; reverse sign when flipping half-equations.
- When applying Nernst, identify n (electrons) and explain what happens when Q > 1 or Q < 1.
Higher Level Thermodynamics & Kinetics
Arrhenius, Gibbs, rate laws, and buffer equations required for HL Paper 3 analysis.
Arrhenius Equation
k rate constant, A frequency factor, E_a activation energy, R gas constant, T Kelvin.
k = A e^{−E_a / (RT)} Gibbs Free Energy
ΔG determines spontaneity, ΔH enthalpy change, ΔS entropy change, T temperature in Kelvin.
ΔG = ΔH − TΔS Rate Law (general)
k rate constant, m and n reaction orders, [A], [B] concentrations.
Rate = k [A]^m [B]^n Buffer pH (Henderson-Hasselbalch)
[A⁻] conjugate base, [HA] weak acid.
pH = pK_a + log₁₀([A⁻]/[HA]) Topic Focus
Arrhenius Analysis
- Take natural logs to linearize ln k = ln A − E_a/(RT) and mention slope/intercept meanings.
- Explain physically what a larger frequency factor A implies (favourable collisions).
Gibbs & Spontaneity
- Discuss temperature dependence by inspecting signs of ΔH and ΔS when predicting spontaneity.
- Relate ΔG to equilibrium via ΔG = −RT ln K when needed.
Rate Laws & Mechanisms
- State overall order (m + n) after writing the rate equation.
- Connect experimental orders to proposed mechanism steps (rate-determining step).
Buffer Calculations
- Clarify concentration ratio [A⁻]/[HA] and ensure both are at equilibrium after dilution.
- Mention buffer capacity limitations when large amounts of acid/base added.
How to Use This Formula Sheet
Boost your Cambridge exam confidence with these proven study strategies from our tutoring experts.
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Annotate Units
Always note mol dm⁻³ vs mol m⁻³ when switching between solution and gas calculations.
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Log Rules Practice
HL kinetics relies on straight-line Arrhenius plots; practice rearranging ln k = ln A − E_a/(RT).
Get Help with IB Chemistry
We drill stoichiometry speed, Hess cycles, equilibrium reasoning, and HL thermodynamics so you gain both accuracy and explanation marks.
Formulas tie directly to the IB Chemistry data booklet; HL-only relationships are grouped for quick Paper 2/3 reference.
Use Kelvin for thermodynamic equations and remember sign conventions for exothermic (negative ΔH) vs endothermic processes.