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 (mol/L)20 minC = ?

A zero-order reaction A → products has a rate constant of 0.05 mol/(L·min). The initial concentration of A is 2 mol/L. Find the concentration CA after 20 min.

k = 0.05 mol/(L·min)CA0 = 2 mol/Lt = 20 min
CA = mol/L
2.Easy
t (min)C/C₀ (%)100 min?

A first-order reaction has a half-life of 25 min. What percentage f of the reactant is still left after 100 min?

t½ = 25 mint = 100 min
f = %
3.Medium
t (min)X (%)t = ?50%

A first-order reaction in a batch reactor has k = 0.01 min⁻¹. How long does it take to reach 50% conversion? Find t.

k = 0.01 min⁻¹X = 50 %
t = min
4.Medium
t (min)C (mol/L)5 minC = ?

A reaction with rate law −rA = k·CA² has k = 0.25 L/(mol·min) and starts at 1 mol/L. Find the concentration CA after 5 min.

k = 0.25 L/(mol·min)CA0 = 1 mol/Lt = 5 min
CA = mol/L
5.Hard
1/Tln kT = 80 °Cln 0.01ln A = ?Ea​ = 50 kJ/mol

A first-order reaction has a rate constant of 0.01 s⁻¹ at 80 °C and an activation energy of 50 kJ/mol. Find the pre-exponential factor A in the Arrhenius equation.

k = 0.01 s⁻¹T = 80 °CEa = 50 kJ/molR = 8.314 J/(mol·K)
A = s⁻¹
6.Hard
Tk20 °Ck1​?10·k1​

A reaction has an activation energy of 75 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 = 75 kJ/molT1 = 20 °Ck2/k1 = 10R = 8.314 J/(mol·K)
T2 = °C

Answer key

  1. 1. CA = 1 mol/L
  2. 2. f = 6.25 %
  3. 3. t = 69.31 min
  4. 4. CA = 0.4444 mol/L
  5. 5. A = 248770 s⁻¹
  6. 6. T2 = 43.71 °C

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