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 (%)12.5 min?

A first-order reaction has a half-life of 5 min. What percentage f of the reactant is still left after 12.5 min?

t½ = 5 mint = 12.5 min
f = %
2.Easy
t (min)C/C₀ (%)32 min?

A first-order reaction has a half-life of 8 min. What percentage f of the reactant is still left after 32 min?

t½ = 8 mint = 32 min
f = %
3.Medium
t (min)X (%)t = ?75%

A second-order reaction (−rA = k·CA²) in a batch reactor has k = 0.1 L/(mol·min) and starts at 1.5 mol/L. How long does it take to reach 75% conversion? Find t.

k = 0.1 L/(mol·min)CA0 = 1.5 mol/LX = 75 %
t = min
4.Medium
t (min)X (%)t = ?90%

A first-order reaction in a batch reactor has k = 0.15 min⁻¹. How long does it take to reach 90% conversion? Find t.

k = 0.15 min⁻¹X = 90 %
t = min
5.Hard
t (min)X (%)15 minX = ?

A first-order reaction has k = 0.002 min⁻¹ at 25 °C and an activation energy of 50 kJ/mol. The batch reactor is now run at 50 °C for 15 min. Find the conversion X reached.

k1 = 0.002 min⁻¹T1 = 25 °CEa = 50 kJ/molT2 = 50 °Ct = 15 minR = 8.314 J/(mol·K)
X = %
6.Hard
Tk25 °C0.0165 °C0.455

The rate constant of a reaction is 0.01 min⁻¹ at 25 °C and 0.455 min⁻¹ at 65 °C. Find the activation energy Ea.

k1 = 0.01 min⁻¹T1 = 25 °Ck2 = 0.455 min⁻¹T2 = 65 °CR = 8.314 J/(mol·K)
Ea = kJ/mol

Answer key

  1. 1. f = 17.68 %
  2. 2. f = 6.25 %
  3. 3. t = 20 min
  4. 4. t = 15.35 min
  5. 5. X = 13.31 %
  6. 6. Ea = 80 kJ/mol

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