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/C₀ (%)37.5 min?

A first-order reaction has a half-life of 25 min. What percentage f of the reactant is still left after 37.5 min?

t½ = 25 mint = 37.5 min
f = %
2.Easy
t (min)C/C₀ (%)4 min?

A first-order reaction has a half-life of 8 min. What percentage f of the reactant is still left after 4 min?

t½ = 8 mint = 4 min
f = %
3.Medium
t (min)X (%)t = ?80%

A first-order reaction in a batch reactor has k = 0.05 min⁻¹. How long does it take to reach 80% conversion? Find t.

k = 0.05 min⁻¹X = 80 %
t = min
4.Medium
t (min)X (%)t = ?75%

A zero-order reaction has k = 0.005 mol/(L·min) and starts at 1.2 mol/L. How long does it take to reach 75% conversion? Find t.

k = 0.005 mol/(L·min)CA0 = 1.2 mol/LX = 75 %
t = min
5.Hard
Tk20 °C0.00235 °C?

A reaction has a rate constant of 0.002 min⁻¹ at 20 °C and an activation energy of 100 kJ/mol. Find the rate constant k2 at 35 °C.

k1 = 0.002 min⁻¹T1 = 20 °CT2 = 35 °CEa = 100 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹
6.Hard
Tk20 °C0.0235 °C0.0445

The rate constant of a reaction is 0.02 min⁻¹ at 20 °C and 0.0445 min⁻¹ at 35 °C. Find the activation energy Ea.

k1 = 0.02 min⁻¹T1 = 20 °Ck2 = 0.0445 min⁻¹T2 = 35 °CR = 8.314 J/(mol·K)
Ea = kJ/mol

Answer key

  1. 1. f = 35.36 %
  2. 2. f = 70.71 %
  3. 3. t = 32.19 min
  4. 4. t = 180 min
  5. 5. k2 = 0.01474 min⁻¹
  6. 6. Ea = 40.04 kJ/mol

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