Equilibrium
Chemical equilibrium, Le Chatelier's principle, acids & bases
Key Concepts
- Dynamic equilibrium: forward and reverse rates are equal
- Le Chatelier's principle: system shifts to oppose a change
- Kc and Kp are related: Kp = Kc(RT)^Δn where Δn = moles of gaseous products − reactants
- Buffer solution resists pH changes; made from weak acid + its conjugate base
- Solubility product (Ksp): ion product > Ksp causes precipitation
Important Formulae
| Equilibrium constant (Kc) | Kc = [products] / [reactants] (coefficients as powers) |
| Kp from Kc | Kp = Kc(RT)^Δn |
| pH definition | pH = −log[H⁺] |
| Water ionisation | Kw = [H⁺][OH⁻] = 10⁻¹⁴ at 25°C |
| Henderson-Hasselbalch | pH = pKa + log([A⁻]/[HA]) |
Quick Tips
- Large K (>10³): reaction heavily favours products; small K (<10⁻³): heavily favours reactants.
- Increasing pressure favours the side with fewer moles of gas.
- Adding a common ion decreases solubility (common ion effect).
Sample Practice Questions
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Salt hydrolysis: CH₃COONa in water gives a solution that is:
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Answer: Basic
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For the reaction A ⇌ 2B, if moles of A = 1 and B = 0 initially, at equilibrium A = 0.5. Kc (in 1 L) = :
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Answer: 2
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At 25°C, Kw = [H⁺][OH⁻] = :
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Answer: 10⁻¹⁴
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Common ion effect reduces:
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Answer: Solubility of a sparingly soluble salt
Practice Questions
Practice 20 randomly selected NEET questions on Equilibrium. Answers are revealed after each question.
Start Practice →Frequently Asked Questions
What are the key concepts in Equilibrium for NEET?
Dynamic equilibrium: forward and reverse rates are equal; Le Chatelier's principle: system shifts to oppose a change; Kc and Kp are related: Kp = Kc(RT)^Δn where Δn = moles of gaseous products − reactants; Buffer solution resists pH changes; made from weak acid + its conjugate base; Solubility product (Ksp): ion product > Ksp causes precipitation.
Which formulae are important for Equilibrium in NEET?
Equilibrium constant (Kc): Kc = [products] / [reactants] (coefficients as powers); Kp from Kc: Kp = Kc(RT)^Δn; pH definition: pH = −log[H⁺]; Water ionisation: Kw = [H⁺][OH⁻] = 10⁻¹⁴ at 25°C; Henderson-Hasselbalch: pH = pKa + log([A⁻]/[HA]).
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