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
2SO2​0.08mol/L+O2​0.25mol/L⇌2SO3​0.15mol/LKc​ = ?

For the reaction 2SO2 + O2 ⇌ 2SO3, the equilibrium concentrations are [SO2] = 0.08 mol/L, [O2] = 0.25 mol/L, [SO3] = 0.15 mol/L. Find the equilibrium constant Kc.

[SO2] = 0.08[O2] = 0.25[SO3] = 0.15
Kc =
2.Easy
CO0.4mol/L+H2​O0.15mol/L⇌CO2​0.1mol/L+H2​0.5mol/LKc​ = ?

For the reaction CO + H2O ⇌ CO2 + H2, the equilibrium concentrations are [CO] = 0.4 mol/L, [H2O] = 0.15 mol/L, [CO2] = 0.1 mol/L, [H2] = 0.5 mol/L. Find the equilibrium constant Kc.

[CO] = 0.4[H2O] = 0.15[CO2] = 0.1[H2] = 0.5
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 = 50. Find the equilibrium concentration [HI].

[H₂]₀ = [I₂]₀ = 1 mol/LKc = 50
[HI] = 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 = 64. Find the equilibrium concentration [HI].

[H₂]₀ = [I₂]₀ = 0.8 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 = 0.2 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 = 0.2
[PCl5] = mol/L
6.Hard
PCl5​PCl3​Cl2​I0.800C−x+x+xE0.8 − xxx

PCl₅ decomposes: PCl₅ ⇌ PCl₃ + Cl₂, with Kc = 0.02 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 = 0.02
[PCl5] = mol/L

Answer key

  1. 1. Kc = 14.06
  2. 2. Kc = 0.8333
  3. 3. [HI] = 1.559 mol/L
  4. 4. [HI] = 1.28 mol/L
  5. 5. [PCl5] = 0.4877 mol/L
  6. 6. [PCl5] = 0.6831 mol/L

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