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

k = 0.02 min⁻¹CA0 = 1.5 mol/Lt = 20 min
CA = mol/L
2.Easy
t (min)C/C₀t½​ = 2 min0.5

A first-order reaction has a half-life of 2 min. Find its rate constant k.

t½ = 2 min
k = min⁻¹
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)15 min0.4

In a first-order reaction the concentration of A falls from 0.5 mol/L to 0.4 mol/L in 15 min. Find the rate constant k.

CA0 = 0.5 mol/LCA = 0.4 mol/Lt = 15 min
k = min⁻¹
5.Hard
t (min)X (%)45 minX = ?

A first-order reaction has k = 0.02 min⁻¹ at 20 °C and an activation energy of 50 kJ/mol. The batch reactor is now run at 30 °C for 45 min. Find the conversion X reached.

k1 = 0.02 min⁻¹T1 = 20 °CEa = 50 kJ/molT2 = 30 °Ct = 45 minR = 8.314 J/(mol·K)
X = %
6.Hard
Tk40 °C0.0550 °C?

A reaction has a rate constant of 0.05 min⁻¹ at 40 °C and an activation energy of 120 kJ/mol. Find the rate constant k2 at 50 °C.

k1 = 0.05 min⁻¹T1 = 40 °CT2 = 50 °CEa = 120 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹

Answer key

  1. 1. CA = 1.005 mol/L
  2. 2. k = 0.3466 min⁻¹
  3. 3. t = 69.31 min
  4. 4. k = 0.01488 min⁻¹
  5. 5. X = 82.98 %
  6. 6. k2 = 0.2082 min⁻¹

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