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/C₀t½​ = 25 min0.5

A first-order reaction has a half-life of 25 min. Find its rate constant k.

t½ = 25 min
k = min⁻¹
2.Easy
t (min)C (mol/L)t½​ = ?C0​/2

A first-order reaction has a rate constant of 0.02 min⁻¹. Find its half-life t½.

k = 0.02 min⁻¹
t½ = min
3.Medium
t (min)C (mol/L)15 minC = ?

A reaction with rate law −rA = k·CA² has k = 0.5 L/(mol·min) and starts at 0.5 mol/L. Find the concentration CA after 15 min.

k = 0.5 L/(mol·min)CA0 = 0.5 mol/Lt = 15 min
CA = mol/L
4.Medium
t (min)X (%)t = ?75%

A second-order reaction (−rA = k·CA²) in a batch reactor has k = 1 L/(mol·min) and starts at 1 mol/L. How long does it take to reach 75% conversion? Find t.

k = 1 L/(mol·min)CA0 = 1 mol/LX = 75 %
t = min
5.Hard
Tk50 °Ck1​?10·k1​

A reaction has an activation energy of 70 kJ/mol. At 50 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 10 times faster?

Ea = 70 kJ/molT1 = 50 °Ck2/k1 = 10R = 8.314 J/(mol·K)
T2 = °C
6.Hard
Tk35 °C0.00250 °C0.00542

The rate constant of a reaction is 0.002 min⁻¹ at 35 °C and 0.00542 min⁻¹ at 50 °C. Find the activation energy Ea.

k1 = 0.002 min⁻¹T1 = 35 °Ck2 = 0.00542 min⁻¹T2 = 50 °CR = 8.314 J/(mol·K)
Ea = kJ/mol

Answer key

  1. 1. k = 0.02773 min⁻¹
  2. 2. t½ = 34.66 min
  3. 3. CA = 0.1053 mol/L
  4. 4. t = 3 min
  5. 5. T2 = 81.33 °C
  6. 6. Ea = 55.02 kJ/mol

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