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/C₀t½​ = 5 min0.5

A first-order reaction has a half-life of 5 min. Find its rate constant k.

t½ = 5 min
k = min⁻¹
2.Easy
t (min)C/C₀ (%)40 min?

A first-order reaction has a half-life of 20 min. What percentage f of the reactant is still left after 40 min?

t½ = 20 mint = 40 min
f = %
3.Medium
t (min)C (mol/L)40 min1.6

In a first-order reaction the concentration of A falls from 2 mol/L to 1.6 mol/L in 40 min. Find the rate constant k.

CA0 = 2 mol/LCA = 1.6 mol/Lt = 40 min
k = min⁻¹
4.Medium
t (min)X (%)t = ?30%

A zero-order reaction has k = 0.04 mol/(L·min) and starts at 1.2 mol/L. How long does it take to reach 30% conversion? Find t.

k = 0.04 mol/(L·min)CA0 = 1.2 mol/LX = 30 %
t = min
5.Hard
Tk35 °C0.00275 °C0.012

The rate constant of a reaction is 0.002 min⁻¹ at 35 °C and 0.012 min⁻¹ at 75 °C. Find the activation energy Ea.

k1 = 0.002 min⁻¹T1 = 35 °Ck2 = 0.012 min⁻¹T2 = 75 °CR = 8.314 J/(mol·K)
Ea = kJ/mol
6.Hard
Tk20 °Ck1​?10·k1​

A reaction has an activation energy of 80 kJ/mol. At 20 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 10 times faster?

Ea = 80 kJ/molT1 = 20 °Ck2/k1 = 10R = 8.314 J/(mol·K)
T2 = °C

Answer key

  1. 1. k = 0.1386 min⁻¹
  2. 2. f = 25 %
  3. 3. k = 0.005579 min⁻¹
  4. 4. t = 9 min
  5. 5. Ea = 39.95 kJ/mol
  6. 6. T2 = 42.12 °C

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