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 0.08 min⁻¹. The initial concentration of A is 1.5 mol/L. Find the concentration CA after 20 min.

k = 0.08 min⁻¹CA0 = 1.5 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 0.08 min⁻¹. Find its half-life t½.

k = 0.08 min⁻¹
t½ = min
3.Medium
t (min)C (mol/L)15 minC = ?

A reaction with rate law −rA = k·CA² has k = 0.1 L/(mol·min) and starts at 1 mol/L. Find the concentration CA after 15 min.

k = 0.1 L/(mol·min)CA0 = 1 mol/Lt = 15 min
CA = mol/L
4.Medium
t (min)X (%)t = ?95%

A first-order reaction in a batch reactor has k = 0.08 min⁻¹. How long does it take to reach 95% conversion? Find t.

k = 0.08 min⁻¹X = 95 %
t = min
5.Hard
CA0​ (mol/L)r (mol/(L·s))run 10.40.02run 21.20.0346n = ?

Two experiments measure the initial rate of A → products. With CA0 = 0.4 mol/L the rate is 0.02 mol/(L·s); with CA0 = 1.2 mol/L it is 0.0346 mol/(L·s). Find the reaction order n with respect to A.

CA0,1 = 0.4 mol/Lr1 = 0.02 mol/(L·s)CA0,2 = 1.2 mol/Lr2 = 0.0346 mol/(L·s)
n =
6.Hard
Tk20 °Ck1​?5·k1​

A reaction has an activation energy of 50 kJ/mol. At 20 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 5 times faster?

Ea = 50 kJ/molT1 = 20 °Ck2/k1 = 5R = 8.314 J/(mol·K)
T2 = °C

Answer key

  1. 1. CA = 0.3028 mol/L
  2. 2. t½ = 8.664 min
  3. 3. CA = 0.4 mol/L
  4. 4. t = 37.45 min
  5. 5. n = 0.4989
  6. 6. T2 = 44.96 °C

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