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
CO0.2mol/L+H2​O0.3mol/L⇌CO2​0.1mol/L+H2​0.15mol/LKc​ = ?

For the reaction CO + H2O ⇌ CO2 + H2, the equilibrium concentrations are [CO] = 0.2 mol/L, [H2O] = 0.3 mol/L, [CO2] = 0.1 mol/L, [H2] = 0.15 mol/L. Find the equilibrium constant Kc.

[CO] = 0.2[H2O] = 0.3[CO2] = 0.1[H2] = 0.15
Kc =
2.Easy
N2​0.05mol/L+3H2​0.5mol/L⇌2NH3​0.25mol/LKc​ = ?

For the reaction N2 + 3H2 ⇌ 2NH3, the equilibrium concentrations are [N2] = 0.05 mol/L, [H2] = 0.5 mol/L, [NH3] = 0.25 mol/L. Find the equilibrium constant Kc.

[N2] = 0.05[H2] = 0.5[NH3] = 0.25
Kc =
3.Medium
H2​I2​HII110C−x−x+2xE1 − x1 − x2x

1 mol/L of H₂ and 1 mol/L of I₂ are put in a container and react: H₂ + I₂ ⇌ 2HI, with Kc = 49. Find the equilibrium concentration [H2].

[H₂]₀ = [I₂]₀ = 1 mol/LKc = 49
[H2] = mol/L
4.Medium
H2​I2​HII0.20.20C−x−x+2xE0.2 − x0.2 − x2x

0.2 mol/L of H₂ and 0.2 mol/L of I₂ are put in a container and react: H₂ + I₂ ⇌ 2HI, with Kc = 9. Find the equilibrium concentration [H2].

[H₂]₀ = [I₂]₀ = 0.2 mol/LKc = 9
[H2] = mol/L
5.Hard
PCl5​PCl3​Cl2​I1.500C−x+x+xE1.5 − xxx

PCl₅ decomposes: PCl₅ ⇌ PCl₃ + Cl₂, with Kc = 0.01 at the reaction temperature. A container starts with 1.5 mol/L of PCl₅ only. Find the equilibrium concentration [Cl2].

[PCl₅]₀ = 1.5 mol/LKc = 0.01
[Cl2] = mol/L
6.Hard
PCl5​PCl3​Cl2​I0.2500C−x+x+xE0.25 − xxx

PCl₅ decomposes: PCl₅ ⇌ PCl₃ + Cl₂, with Kc = 0.02 at the reaction temperature. A container starts with 0.25 mol/L of PCl₅ only. Find the equilibrium concentration [Cl2].

[PCl₅]₀ = 0.25 mol/LKc = 0.02
[Cl2] = mol/L

Answer key

  1. 1. Kc = 0.25
  2. 2. Kc = 10
  3. 3. [H2] = 0.2222 mol/L
  4. 4. [H2] = 0.08 mol/L
  5. 5. [Cl2] = 0.1176 mol/L
  6. 6. [Cl2] = 0.06141 mol/L

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