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 (mol/L)40 minC = ?

A first-order reaction A → products has a rate constant of 0.02 min⁻¹. The initial concentration of A is 1.2 mol/L. Find the concentration CA after 40 min.

k = 0.02 min⁻¹CA0 = 1.2 mol/Lt = 40 min
CA = mol/L
3.Medium
t (min)X (%)t = ?50%

A first-order reaction in a batch reactor has k = 0.02 min⁻¹. How long does it take to reach 50% conversion? Find t.

k = 0.02 min⁻¹X = 50 %
t = min
4.Medium
t (min)X (%)t = ?60%

A second-order reaction (−rA = k·CA²) in a batch reactor has k = 1 L/(mol·min) and starts at 1 mol/L. How long does it take to reach 60% conversion? Find t.

k = 1 L/(mol·min)CA0 = 1 mol/LX = 60 %
t = min
5.Hard
Tk35 °C0.00245 °C?

A reaction has a rate constant of 0.002 min⁻¹ at 35 °C and an activation energy of 40 kJ/mol. Find the rate constant k2 at 45 °C.

k1 = 0.002 min⁻¹T1 = 35 °CT2 = 45 °CEa = 40 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹
6.Hard
Tk30 °Ck1​?3·k1​

A reaction has an activation energy of 75 kJ/mol. At 30 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 3 times faster?

Ea = 75 kJ/molT1 = 30 °Ck2/k1 = 3R = 8.314 J/(mol·K)
T2 = °C

Answer key

  1. 1. k = 0.1386 min⁻¹
  2. 2. CA = 0.5392 mol/L
  3. 3. t = 34.66 min
  4. 4. t = 1.5 min
  5. 5. k2 = 0.003267 min⁻¹
  6. 6. T2 = 41.62 °C

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