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Class 11 and 12 Chemistry Formula Sheet
The chemistry relations worth memorising, with the constants you are expected to know. Physical chemistry is where formulas earn marks; inorganic and organic reward patterns instead.
23 formulas across 4 sections.
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Constants worth knowing
| What | Formula | Symbols |
|---|---|---|
| Avogadro's number | NA = 6.022 × 10²³ mol⁻¹ | particles in one mole |
| Gas constant | R = 8.314 J mol⁻¹ K⁻¹ = 0.0821 L atm mol⁻¹ K⁻¹ | pick the unit that matches the question |
| Molar volume at STP | 22.4 L mol⁻¹ | for an ideal gas |
| Faraday constant | F = 96500 C mol⁻¹ | charge on one mole of electrons |
Mole concept and solutions
| What | Formula | Symbols |
|---|---|---|
| Moles | n = given mass / molar mass | the starting point of most numericals |
| Molarity | M = moles of solute / volume of solution in litres | changes with temperature |
| Molality | m = moles of solute / mass of solvent in kg | independent of temperature |
| Mole fraction | x = n(component) / n(total) | dimensionless, sums to 1 |
| Raoult's law | p = x(solvent) p° | for an ideal solution |
| Elevation of boiling point | ΔTb = Kb·m | colligative |
| Depression of freezing point | ΔTf = Kf·m | colligative |
| Osmotic pressure | π = CRT | C molarity |
Thermodynamics and equilibrium
| What | Formula | Symbols |
|---|---|---|
| First law | ΔU = q + w | sign convention matters |
| Enthalpy | ΔH = ΔU + ΔnRT | Δn = moles of gaseous products − reactants |
| Gibbs free energy | ΔG = ΔH − TΔS | negative means spontaneous |
| Equilibrium and free energy | ΔG° = −2.303 RT log K | links K to spontaneity |
| pH | pH = −log[H⁺] | pOH = −log[OH⁻] |
| Relation | pH + pOH = 14 | at 25 °C |
Kinetics and electrochemistry
| What | Formula | Symbols |
|---|---|---|
| First order rate constant | k = (2.303/t) log(a/(a−x)) | units: s⁻¹ |
| First order half-life | t½ = 0.693/k | independent of initial concentration |
| Arrhenius equation | k = A e−Ea/RT | Ea activation energy |
| Nernst equation | E = E° − (0.0591/n) log Q | at 25 °C |
| Faraday's first law | m = ZIt | Z electrochemical equivalent |
Taught by Darshit Bhatt, founder and lead faculty at Darshit Sir Institute. Instrumentation and Control engineer, with a master's degree and a chartered degree, teaching in Paldi, Ahmedabad since 2006.
Chapter by chapter
Every chapter on its own page.
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