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 (%)50 min?

A first-order reaction has a half-life of 25 min. What percentage f of the reactant is still left after 50 min?

t½ = 25 mint = 50 min
f = %
2.Easy
t (min)C (mol/L)t½​ = ?C0​/2

A first-order reaction has a rate constant of 0.02 min⁻¹. Find its half-life t½.

k = 0.02 min⁻¹
t½ = min
3.Medium
t (min)C (mol/L)30 minC = ?

A reaction with rate law −rA = k·CA² has k = 1 L/(mol·min) and starts at 2 mol/L. Find the concentration CA after 30 min.

k = 1 L/(mol·min)CA0 = 2 mol/Lt = 30 min
CA = mol/L
4.Medium
t (min)X (%)t = ?60%

A first-order reaction in a batch reactor has k = 0.1 min⁻¹. How long does it take to reach 60% conversion? Find t.

k = 0.1 min⁻¹X = 60 %
t = min
5.Hard
Tk20 °C0.00535 °C?

A reaction has a rate constant of 0.005 min⁻¹ at 20 °C and an activation energy of 40 kJ/mol. Find the rate constant k2 at 35 °C.

k1 = 0.005 min⁻¹T1 = 20 °CT2 = 35 °CEa = 40 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹
6.Hard
Tk30 °Ck1​?10·k1​

A reaction has an activation energy of 50 kJ/mol. At 30 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 10 times faster?

Ea = 50 kJ/molT1 = 30 °Ck2/k1 = 10R = 8.314 J/(mol·K)
T2 = °C

Answer key

  1. 1. f = 25 %
  2. 2. t½ = 34.66 min
  3. 3. CA = 0.03279 mol/L
  4. 4. t = 9.163 min
  5. 5. k2 = 0.01112 min⁻¹
  6. 6. T2 = 69.81 °C

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