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
H2​0.25mol/L+I2​0.1mol/L⇌2HI0.4mol/LKc​ = ?

For the reaction H2 + I2 ⇌ 2HI, the equilibrium concentrations are [H2] = 0.25 mol/L, [I2] = 0.1 mol/L, [HI] = 0.4 mol/L. Find the equilibrium constant Kc.

[H2] = 0.25[I2] = 0.1[HI] = 0.4
Kc =
2.Easy
H2​0.2mol/L+I2​0.05mol/L⇌2HI0.5mol/LKc​ = ?

For the reaction H2 + I2 ⇌ 2HI, the equilibrium concentrations are [H2] = 0.2 mol/L, [I2] = 0.05 mol/L, [HI] = 0.5 mol/L. Find the equilibrium constant Kc.

[H2] = 0.2[I2] = 0.05[HI] = 0.5
Kc =
3.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 = 50. Find the equilibrium concentration [H2].

[H₂]₀ = [I₂]₀ = 0.2 mol/LKc = 50
[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 = 54. Find the equilibrium concentration [HI].

[H₂]₀ = [I₂]₀ = 0.25 mol/LKc = 54
[HI] = mol/L
5.Hard
PCl5​PCl3​Cl2​I0.400C−x+x+xE0.4 − xxx

PCl₅ decomposes: PCl₅ ⇌ PCl₃ + Cl₂, with Kc = 0.1 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 = 0.1
[PCl5] = mol/L
6.Hard
PCl5​PCl3​Cl2​I1.500C−x+x+xE1.5 − xxx

PCl₅ decomposes: PCl₅ ⇌ PCl₃ + Cl₂, with Kc = 0.04 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 = 0.04
[Cl2] = mol/L

Answer key

  1. 1. Kc = 6.4
  2. 2. Kc = 25
  3. 3. [H2] = 0.0441 mol/L
  4. 4. [HI] = 0.393 mol/L
  5. 5. [PCl5] = 0.2438 mol/L
  6. 6. [Cl2] = 0.2258 mol/L

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