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)90 minC = ?

A first-order reaction A → products has a rate constant of 0.01 min⁻¹. The initial concentration of A is 1 mol/L. Find the concentration CA after 90 min.

k = 0.01 min⁻¹CA0 = 1 mol/Lt = 90 min
CA = mol/L
2.Easy
t (min)C/C₀ (%)10 min?

A first-order reaction has a half-life of 5 min. What percentage f of the reactant is still left after 10 min?

t½ = 5 mint = 10 min
f = %
3.Medium
t (min)C (mol/L)t½​ = ?C0​/2

A second-order reaction (−rA = k·CA²) has k = 0.1 L/(mol·min) and an initial concentration of 2 mol/L. Find its first half-life t½.

k = 0.1 L/(mol·min)CA0 = 2 mol/L
t½ = min
4.Medium
t (min)X (%)t = ?90%

A first-order reaction in a batch reactor has k = 0.01 min⁻¹. How long does it take to reach 90% conversion? Find t.

k = 0.01 min⁻¹X = 90 %
t = min
5.Hard
t (min)X (%)15 minX = ?

A first-order reaction has k = 0.02 min⁻¹ at 25 °C and an activation energy of 90 kJ/mol. The batch reactor is now run at 50 °C for 15 min. Find the conversion X reached.

k1 = 0.02 min⁻¹T1 = 25 °CEa = 90 kJ/molT2 = 50 °Ct = 15 minR = 8.314 J/(mol·K)
X = %
6.Hard
Tk20 °Ck1​?2·k1​

A reaction has an activation energy of 55 kJ/mol. At 20 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 2 times faster?

Ea = 55 kJ/molT1 = 20 °Ck2/k1 = 2R = 8.314 J/(mol·K)
T2 = °C

Answer key

  1. 1. CA = 0.4066 mol/L
  2. 2. f = 25 %
  3. 3. t½ = 5 min
  4. 4. t = 230.3 min
  5. 5. X = 99.31 %
  6. 6. T2 = 29.29 °C

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