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
CA​ (mol/L)r1.5r = ?CB​ = 0.6 mol/L

The reaction A + B → C follows the rate law r = k·CA, with k = 0.5 s⁻¹. Find the reaction rate r when CA = 1.5 mol/L and CB = 0.6 mol/L.

r = k·CAk = 0.5 s⁻¹CA = 1.5 mol/LCB = 0.6 mol/L
r = mol/(L·s)
2.Easy
t (min)C (mol/L)5 minC = ?

A first-order reaction A → products has a rate constant of 0.15 min⁻¹. The initial concentration of A is 2 mol/L. Find the concentration CA after 5 min.

k = 0.15 min⁻¹CA0 = 2 mol/Lt = 5 min
CA = mol/L
3.Medium
t (min)X (%)t = ?50%

A first-order reaction in a batch reactor has k = 0.05 min⁻¹. How long does it take to reach 50% conversion? Find t.

k = 0.05 min⁻¹X = 50 %
t = min
4.Medium
t (min)C (mol/L)t½​ = ?C0​/2

A second-order reaction (−rA = k·CA²) has k = 0.25 L/(mol·min) and an initial concentration of 2 mol/L. Find its first half-life t½.

k = 0.25 L/(mol·min)CA0 = 2 mol/L
t½ = min
5.Hard
Tk30 °Ck1​?10·k1​

A reaction has an activation energy of 50 kJ/mol. At 30 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 10 times faster?

Ea = 50 kJ/molT1 = 30 °Ck2/k1 = 10R = 8.314 J/(mol·K)
T2 = °C
6.Hard
Tk40 °C0.0560 °C0.398

The rate constant of a reaction is 0.05 min⁻¹ at 40 °C and 0.398 min⁻¹ at 60 °C. Find the activation energy Ea.

k1 = 0.05 min⁻¹T1 = 40 °Ck2 = 0.398 min⁻¹T2 = 60 °CR = 8.314 J/(mol·K)
Ea = kJ/mol

Answer key

  1. 1. r = 0.75 mol/(L·s)
  2. 2. CA = 0.9447 mol/L
  3. 3. t = 13.86 min
  4. 4. t½ = 2 min
  5. 5. T2 = 69.81 °C
  6. 6. Ea = 89.96 kJ/mol

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