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 (%)125 min?

A first-order reaction has a half-life of 25 min. What percentage f of the reactant is still left after 125 min?

t½ = 25 mint = 125 min
f = %
2.Easy
t (min)C (mol/L)t½​ = ?C0​/2

A first-order reaction has a rate constant of 0.01 min⁻¹. Find its half-life t½.

k = 0.01 min⁻¹
t½ = min
3.Medium
t (min)X (%)t = ?80%

A second-order reaction (−rA = k·CA²) in a batch reactor has k = 0.1 L/(mol·min) and starts at 0.5 mol/L. How long does it take to reach 80% conversion? Find t.

k = 0.1 L/(mol·min)CA0 = 0.5 mol/LX = 80 %
t = min
4.Medium
t (min)X (%)t = ?90%

A zero-order reaction has k = 0.02 mol/(L·min) and starts at 0.8 mol/L. How long does it take to reach 90% conversion? Find t.

k = 0.02 mol/(L·min)CA0 = 0.8 mol/LX = 90 %
t = min
5.Hard
Tk30 °C0.0250 °C?

A reaction has a rate constant of 0.02 min⁻¹ at 30 °C and an activation energy of 90 kJ/mol. Find the rate constant k2 at 50 °C.

k1 = 0.02 min⁻¹T1 = 30 °CT2 = 50 °CEa = 90 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹
6.Hard
Tk25 °C0.165 °C1.09

The rate constant of a reaction is 0.1 min⁻¹ at 25 °C and 1.09 min⁻¹ at 65 °C. Find the activation energy Ea.

k1 = 0.1 min⁻¹T1 = 25 °Ck2 = 1.09 min⁻¹T2 = 65 °CR = 8.314 J/(mol·K)
Ea = kJ/mol

Answer key

  1. 1. f = 3.125 %
  2. 2. t½ = 69.31 min
  3. 3. t = 80 min
  4. 4. t = 36 min
  5. 5. k2 = 0.1823 min⁻¹
  6. 6. Ea = 50.06 kJ/mol

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