Chemical equilibrium worksheet with answers

Free printable Chemical equilibrium worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
PCl5​0.3mol/L⇌PCl3​0.08mol/L+Cl2​0.1mol/LKc​ = ?

For the reaction PCl5 ⇌ PCl3 + Cl2, the equilibrium concentrations are [PCl5] = 0.3 mol/L, [PCl3] = 0.08 mol/L, [Cl2] = 0.1 mol/L. Find the equilibrium constant Kc.

[PCl5] = 0.3[PCl3] = 0.08[Cl2] = 0.1
Kc =
2.Easy
CO0.3mol/L+H2​O0.05mol/L⇌CO2​0.05mol/L+H2​0.25mol/LKc​ = ?

For the reaction CO + H2O ⇌ CO2 + H2, the equilibrium concentrations are [CO] = 0.3 mol/L, [H2O] = 0.05 mol/L, [CO2] = 0.05 mol/L, [H2] = 0.25 mol/L. Find the equilibrium constant Kc.

[CO] = 0.3[H2O] = 0.05[CO2] = 0.05[H2] = 0.25
Kc =
3.Medium
H2​I2​HII0.10.10C−x−x+2xE0.1 − x0.1 − x2x

0.1 mol/L of H₂ and 0.1 mol/L of I₂ are put in a container and react: H₂ + I₂ ⇌ 2HI, with Kc = 16. Find the equilibrium concentration [H2].

[H₂]₀ = [I₂]₀ = 0.1 mol/LKc = 16
[H2] = mol/L
4.Medium
H2​I2​HII0.80.80C−x−x+2xE0.8 − x0.8 − x2x

0.8 mol/L of H₂ and 0.8 mol/L of I₂ are put in a container and react: H₂ + I₂ ⇌ 2HI, with Kc = 50. Find the equilibrium concentration [HI].

[H₂]₀ = [I₂]₀ = 0.8 mol/LKc = 50
[HI] = mol/L
5.Hard
PCl5​PCl3​Cl2​I0.200C−x+x+xE0.2 − xxx

PCl₅ decomposes: PCl₅ ⇌ PCl₃ + Cl₂, with Kc = 0.02 at the reaction temperature. A container starts with 0.2 mol/L of PCl₅ only. Find the equilibrium concentration [PCl5].

[PCl₅]₀ = 0.2 mol/LKc = 0.02
[PCl5] = mol/L
6.Hard
PCl5​PCl3​Cl2​I100C−x+x+xE1 − xxx

PCl₅ decomposes: PCl₅ ⇌ PCl₃ + Cl₂, with Kc = 0.08 at the reaction temperature. A container starts with 1 mol/L of PCl₅ only. Find the equilibrium concentration [Cl2].

[PCl₅]₀ = 1 mol/LKc = 0.08
[Cl2] = mol/L

Answer key

  1. 1. Kc = 0.02667
  2. 2. Kc = 0.8333
  3. 3. [H2] = 0.03333 mol/L
  4. 4. [HI] = 1.247 mol/L
  5. 5. [PCl5] = 0.146 mol/L
  6. 6. [Cl2] = 0.2457 mol/L

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