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)40 minC = ?

A first-order reaction A → products has a rate constant of 0.05 min⁻¹. The initial concentration of A is 2 mol/L. Find the concentration CA after 40 min.

k = 0.05 min⁻¹CA0 = 2 mol/Lt = 40 min
CA = mol/L
2.Easy
t (min)C (mol/L)5 minC = ?

A first-order reaction A → products has a rate constant of 0.25 min⁻¹. The initial concentration of A is 1.5 mol/L. Find the concentration CA after 5 min.

k = 0.25 min⁻¹CA0 = 1.5 mol/Lt = 5 min
CA = mol/L
3.Medium
t (min)C (mol/L)t½​ = ?C0​/2

A second-order reaction (−rA = k·CA²) has k = 0.8 L/(mol·min) and an initial concentration of 1.5 mol/L. Find its first half-life t½.

k = 0.8 L/(mol·min)CA0 = 1.5 mol/L
t½ = min
4.Medium
t (min)X (%)t = ?50%

A first-order reaction in a batch reactor has k = 0.01 min⁻¹. How long does it take to reach 50% conversion? Find t.

k = 0.01 min⁻¹X = 50 %
t = min
5.Hard
Tk20 °Ck1​?3·k1​

A reaction has an activation energy of 70 kJ/mol. At 20 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 3 times faster?

Ea = 70 kJ/molT1 = 20 °Ck2/k1 = 3R = 8.314 J/(mol·K)
T2 = °C
6.Hard
Tk40 °C0.160 °C?

A reaction has a rate constant of 0.1 min⁻¹ at 40 °C and an activation energy of 50 kJ/mol. Find the rate constant k2 at 60 °C.

k1 = 0.1 min⁻¹T1 = 40 °CT2 = 60 °CEa = 50 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹

Answer key

  1. 1. CA = 0.2707 mol/L
  2. 2. CA = 0.4298 mol/L
  3. 3. t½ = 0.8333 min
  4. 4. t = 69.31 min
  5. 5. T2 = 31.66 °C
  6. 6. k2 = 0.3167 min⁻¹

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