Reaction kinetics worksheet with answers

Free printable Reaction kinetics 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
t (min)C (mol/L)t½​ = ?C0​/2

A first-order reaction has a rate constant of 0.1 min⁻¹. Find its half-life t½.

k = 0.1 min⁻¹
t½ = min
2.Easy
t (min)C (mol/L)20 minC = ?

A first-order reaction A → products has a rate constant of 0.01 min⁻¹. The initial concentration of A is 1.2 mol/L. Find the concentration CA after 20 min.

k = 0.01 min⁻¹CA0 = 1.2 mol/Lt = 20 min
CA = mol/L
3.Medium
t (min)X (%)t = ?50%

A first-order reaction in a batch reactor has k = 0.02 min⁻¹. How long does it take to reach 50% conversion? Find t.

k = 0.02 min⁻¹X = 50 %
t = min
4.Medium
t (min)C (mol/L)5 minC = ?

A reaction with rate law −rA = k·CA² has k = 0.1 L/(mol·min) and starts at 2 mol/L. Find the concentration CA after 5 min.

k = 0.1 L/(mol·min)CA0 = 2 mol/Lt = 5 min
CA = mol/L
5.Hard
Tk40 °C0.00565 °C?

A reaction has a rate constant of 0.005 min⁻¹ at 40 °C and an activation energy of 50 kJ/mol. Find the rate constant k2 at 65 °C.

k1 = 0.005 min⁻¹T1 = 40 °CT2 = 65 °CEa = 50 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹
6.Hard
Tk30 °C0.140 °C0.166

The rate constant of a reaction is 0.1 min⁻¹ at 30 °C and 0.166 min⁻¹ at 40 °C. Find the activation energy Ea.

k1 = 0.1 min⁻¹T1 = 30 °Ck2 = 0.166 min⁻¹T2 = 40 °CR = 8.314 J/(mol·K)
Ea = kJ/mol

Answer key

  1. 1. t½ = 6.931 min
  2. 2. CA = 0.9825 mol/L
  3. 3. t = 34.66 min
  4. 4. CA = 1 mol/L
  5. 5. k2 = 0.02068 min⁻¹
  6. 6. Ea = 40 kJ/mol

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