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 zero-order reaction A → products has a rate constant of 0.04 mol/(L·min). The initial concentration of A is 2 mol/L. Find the concentration CA after 40 min.

k = 0.04 mol/(L·min)CA0 = 2 mol/Lt = 40 min
CA = mol/L
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)X (%)t = ?75%

A first-order reaction in a batch reactor has k = 0.08 min⁻¹. How long does it take to reach 75% conversion? Find t.

k = 0.08 min⁻¹X = 75 %
t = min
4.Medium
t (min)C (mol/L)2 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 2 min.

k = 0.5 L/(mol·min)CA0 = 0.5 mol/Lt = 2 min
CA = mol/L
5.Hard
t (min)X (%)15 minX = ?

A first-order reaction has k = 0.01 min⁻¹ at 30 °C and an activation energy of 75 kJ/mol. The batch reactor is now run at 45 °C for 15 min. Find the conversion X reached.

k1 = 0.01 min⁻¹T1 = 30 °CEa = 75 kJ/molT2 = 45 °Ct = 15 minR = 8.314 J/(mol·K)
X = %
6.Hard
Tk50 °Ck1​?5·k1​

A reaction has an activation energy of 60 kJ/mol. At 50 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 5 times faster?

Ea = 60 kJ/molT1 = 50 °Ck2/k1 = 5R = 8.314 J/(mol·K)
T2 = °C

Answer key

  1. 1. CA = 0.4 mol/L
  2. 2. t½ = 34.66 min
  3. 3. t = 17.33 min
  4. 4. CA = 0.3333 mol/L
  5. 5. X = 45.67 %
  6. 6. T2 = 75.1 °C

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