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 first-order reaction A → products has a rate constant of 0.01 min⁻¹. The initial concentration of A is 0.8 mol/L. Find the concentration CA after 20 min.

k = 0.01 min⁻¹CA0 = 0.8 mol/Lt = 20 min
CA = mol/L
2.Easy
t (min)C (mol/L)t½​ = ?C0​/2

A first-order reaction has a rate constant of 0.1 min⁻¹. Find its half-life t½.

k = 0.1 min⁻¹
t½ = min
3.Medium
t (min)X (%)t = ?80%

A zero-order reaction has k = 0.01 mol/(L·min) and starts at 0.8 mol/L. How long does it take to reach 80% conversion? Find t.

k = 0.01 mol/(L·min)CA0 = 0.8 mol/LX = 80 %
t = min
4.Medium
t (min)C (mol/L)t½​ = ?C0​/2

A second-order reaction (−rA = k·CA²) has k = 0.02 L/(mol·min) and an initial concentration of 1.5 mol/L. Find its first half-life t½.

k = 0.02 L/(mol·min)CA0 = 1.5 mol/L
t½ = min
5.Hard
Tk30 °C0.00550 °C?

A reaction has a rate constant of 0.005 min⁻¹ at 30 °C and an activation energy of 100 kJ/mol. Find the rate constant k2 at 50 °C.

k1 = 0.005 min⁻¹T1 = 30 °CT2 = 50 °CEa = 100 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹
6.Hard
Tk30 °Ck1​?5·k1​

A reaction has an activation energy of 40 kJ/mol. At 30 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 5 times faster?

Ea = 40 kJ/molT1 = 30 °Ck2/k1 = 5R = 8.314 J/(mol·K)
T2 = °C

Answer key

  1. 1. CA = 0.655 mol/L
  2. 2. t½ = 6.931 min
  3. 3. t = 64 min
  4. 4. t½ = 33.33 min
  5. 5. k2 = 0.05827 min⁻¹
  6. 6. T2 = 64.21 °C

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