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​0.05mol/L+O2​0.5mol/L⇌2SO3​0.05mol/LKc​ = ?

For the reaction 2SO2 + O2 ⇌ 2SO3, the equilibrium concentrations are [SO2] = 0.05 mol/L, [O2] = 0.5 mol/L, [SO3] = 0.05 mol/L. Find the equilibrium constant Kc.

[SO2] = 0.05[O2] = 0.5[SO3] = 0.05
Kc =
2.Easy
N2​O4​0.05mol/L⇌2NO2​0.05mol/LKc​ = ?

For the reaction N2O4 ⇌ 2NO2, the equilibrium concentrations are [N2O4] = 0.05 mol/L, [NO2] = 0.05 mol/L. Find the equilibrium constant Kc.

[N2O4] = 0.05[NO2] = 0.05
Kc =
3.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 = 9. Find the equilibrium concentration [HI].

[H₂]₀ = [I₂]₀ = 0.8 mol/LKc = 9
[HI] = mol/L
4.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 = 9. Find the equilibrium concentration [H2].

[H₂]₀ = [I₂]₀ = 1 mol/LKc = 9
[H2] = mol/L
5.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
6.Hard
PCl5​PCl3​Cl2​I0.2500C−x+x+xE0.25 − xxx

PCl₅ decomposes: PCl₅ ⇌ PCl₃ + Cl₂, with Kc = 0.1 at the reaction temperature. A container starts with 0.25 mol/L of PCl₅ only. Find the equilibrium concentration [PCl5].

[PCl₅]₀ = 0.25 mol/LKc = 0.1
[PCl5] = mol/L

Answer key

  1. 1. Kc = 2
  2. 2. Kc = 0.05
  3. 3. [HI] = 0.96 mol/L
  4. 4. [H2] = 0.4 mol/L
  5. 5. [PCl5] = 0.16 mol/L
  6. 6. [PCl5] = 0.1342 mol/L

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