Chemical Equilibrium Formulas

One needs to be aware of the forward reaction or reverse reaction while dealing with Chemical Equilibrium. You might not be aware of all the technicalities regarding Chemical Equilibrium. To help you with that we have jotted down the Important Formulae concerning the Chemical Equilibrium. All the vital formulas that you might need while solving the problems of Chemical Equilibrium can get here.

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Chemical Equilibrium Formula Sheet & Tables

Support your learning regarding the Concept of Chemical Equilibrium with the List of Formulas prevailing. Grab the opportunity and make the most out of the Chemical Equilibrium Formulae Sheet to have a grip on the concept. Use the Formulas for Chemical Equilibrium to have a quick revision and learn the fundamentals involved.

1. Free Energy changes (ΔG):

  • If ΔG = 0 then reversible reaction would be in equilibrium.
  • If ΔG = (+) ve then equilibrium will be displace in backward direction.
  • If ΔG = (-) ve then equilibrium will displace in forward direction.

2. Rate of Reaction (r):
(a) If A + B \(\rightleftharpoons \) C + D
r = – dCA/dt = – dCB/dt = dCC/dt = dCD/dt

(b) For 2A \(\rightleftharpoons \) C + 1/2D
r = – dCA/2dt = dCC/dt = 2dCD/dt

3. (a) K (Equilibrium Constant Kc & Kp) is constant, Factors other than temperature & stoichiometry of reaction do not affects its value.

(b) For endothermic reactions: (ΔH = + x KCal)
Chemical Equilibrium formulas img 1

(c) For exothermic reactions: (ΔH = – x KCal)
Chemical Equilibrium formulas img 2

4. For n1A + n2B \(\rightleftharpoons \) m1C + m2D

  • Kc\(\frac{[\mathrm{C}]^{\mathrm{m}_{\mathrm{l}}}[\mathrm{D}]^{\mathrm{m}_{2}}}{[\mathrm{A}]^{\mathrm{n}_{1}}[\mathrm{B}]^{\mathrm{n}_{2}}}\)
  • Kp\(\frac{P_{c}^{m_{1}} P_{D}^{m_{2}}}{P_{A}^{n_{1}} P_{B}^{n_{2}}}\)
  • Kp = Kc(RT)Δn
  • Partial pressure of any gas = mole fraction × total pressure

Note: This formula is used at equilibrium
(e) At equilibrium rf = rb

5. (a) Practical Verification of Law of Mass action → Bondenstein

(b) Equilibrium in liquid state
CH3COOH(l) + C2H5OH(l) \(\rightleftharpoons \) CH3COOC2H5(l) + H2O(l). was firstly studied by Berthelot & Gilies.

6. (a) x = \(\frac{\mathrm{d}_{\mathrm{t}}-\mathrm{d}_{0}}{\mathrm{d}_{0}}=\frac{\mathrm{M}_{\mathrm{t}}-\mathrm{M}_{0}}{\mathrm{M}_{0}}\)
for PCl5 \(\rightleftharpoons \) PCl3 + Cl2
Mol. wt. & Vapour density of PCl5 are 208.5 & 104.25 respectively, vapour density = mol. wt./2

(b) In General if A \(\rightleftharpoons \) nB then x = \(\frac{d_{t}-d_{0}}{(n-1) d_{0}}\)

7. Some other important points:

  • Kc unit → (moles/lit)An
  • Kp unit → (atm)Δn
  • Total moles at equilibrium = [total initial moles + Δn (x)]
  • Time required to establish equilibrium α 1/Kc
  • If in any heterogenous equilibrium solid substance is also present then its active mass & partial pressure is assumed 1.

Le chatelier’s principal:

  • Increase of reactant cone. (Shift forward)
  • Decrease of reactant cone. (Shift backward)
  • Increase of pressure (from more moles to less moles)
  • Decrease of pressure (from less moles to more moles)

8. Summary various homogenous equilibrium:
Chemical Equilibrium formulas img 3

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