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
CO0.5mol/L+H2​O0.12mol/L⇌CO2​0.4mol/L+H2​0.25mol/LKc​ = ?

For the reaction CO + H2O ⇌ CO2 + H2, the equilibrium concentrations are [CO] = 0.5 mol/L, [H2O] = 0.12 mol/L, [CO2] = 0.4 mol/L, [H2] = 0.25 mol/L. Find the equilibrium constant Kc.

[CO] = 0.5[H2O] = 0.12[CO2] = 0.4[H2] = 0.25
Kc =
2.Easy
N2​0.1mol/L+3H2​0.15mol/L⇌2NH3​0.15mol/LKc​ = ?

For the reaction N2 + 3H2 ⇌ 2NH3, the equilibrium concentrations are [N2] = 0.1 mol/L, [H2] = 0.15 mol/L, [NH3] = 0.15 mol/L. Find the equilibrium constant Kc.

[N2] = 0.1[H2] = 0.15[NH3] = 0.15
Kc =
3.Medium
H2​I2​HII0.250.250C−x−x+2xE0.25 − x0.25 − x2x

0.25 mol/L of H₂ and 0.25 mol/L of I₂ are put in a container and react: H₂ + I₂ ⇌ 2HI, with Kc = 25. Find the equilibrium concentration [H2].

[H₂]₀ = [I₂]₀ = 0.25 mol/LKc = 25
[H2] = mol/L
4.Medium
H2​I2​HII0.250.250C−x−x+2xE0.25 − x0.25 − x2x

0.25 mol/L of H₂ and 0.25 mol/L of I₂ are put in a container and react: H₂ + I₂ ⇌ 2HI, with Kc = 64. Find the equilibrium concentration [HI].

[H₂]₀ = [I₂]₀ = 0.25 mol/LKc = 64
[HI] = mol/L
5.Hard
PCl5​PCl3​Cl2​I0.800C−x+x+xE0.8 − xxx

PCl₅ decomposes: PCl₅ ⇌ PCl₃ + Cl₂, with Kc = 0.05 at the reaction temperature. A container starts with 0.8 mol/L of PCl₅ only. Find the equilibrium concentration [PCl5].

[PCl₅]₀ = 0.8 mol/LKc = 0.05
[PCl5] = mol/L
6.Hard
PCl5​PCl3​Cl2​I0.200C−x+x+xE0.2 − xxx

PCl₅ decomposes: PCl₅ ⇌ PCl₃ + Cl₂, with Kc = 0.01 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 = 0.01
[PCl5] = mol/L

Answer key

  1. 1. Kc = 1.667
  2. 2. Kc = 66.67
  3. 3. [H2] = 0.07143 mol/L
  4. 4. [HI] = 0.4 mol/L
  5. 5. [PCl5] = 0.6234 mol/L
  6. 6. [PCl5] = 0.16 mol/L

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