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
N2​0.12mol/L+3H2​0.25mol/L⇌2NH3​0.12mol/LKc​ = ?

For the reaction N2 + 3H2 ⇌ 2NH3, the equilibrium concentrations are [N2] = 0.12 mol/L, [H2] = 0.25 mol/L, [NH3] = 0.12 mol/L. Find the equilibrium constant Kc.

[N2] = 0.12[H2] = 0.25[NH3] = 0.12
Kc =
2.Easy
2SO2​0.4mol/L+O2​0.3mol/L⇌2SO3​0.4mol/LKc​ = ?

For the reaction 2SO2 + O2 ⇌ 2SO3, the equilibrium concentrations are [SO2] = 0.4 mol/L, [O2] = 0.3 mol/L, [SO3] = 0.4 mol/L. Find the equilibrium constant Kc.

[SO2] = 0.4[O2] = 0.3[SO3] = 0.4
Kc =
3.Medium
H2​I2​HII0.50.50C−x−x+2xE0.5 − x0.5 − x2x

0.5 mol/L of H₂ and 0.5 mol/L of I₂ are put in a container and react: H₂ + I₂ ⇌ 2HI, with Kc = 25. Find the equilibrium concentration [HI].

[H₂]₀ = [I₂]₀ = 0.5 mol/LKc = 25
[HI] = 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 = 64. Find the equilibrium concentration [HI].

[H₂]₀ = [I₂]₀ = 0.2 mol/LKc = 64
[HI] = mol/L
5.Hard
PCl5​PCl3​Cl2​I0.400C−x+x+xE0.4 − xxx

PCl₅ decomposes: PCl₅ ⇌ PCl₃ + Cl₂, with Kc = 0.05 at the reaction temperature. A container starts with 0.4 mol/L of PCl₅ only. Find the equilibrium concentration [PCl5].

[PCl₅]₀ = 0.4 mol/LKc = 0.05
[PCl5] = mol/L
6.Hard
PCl5​PCl3​Cl2​I0.2500C−x+x+xE0.25 − xxx

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

Answer key

  1. 1. Kc = 7.68
  2. 2. Kc = 3.333
  3. 3. [HI] = 0.7143 mol/L
  4. 4. [HI] = 0.32 mol/L
  5. 5. [PCl5] = 0.2814 mol/L
  6. 6. [PCl5] = 0.2048 mol/L

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