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)5 minC = ?

A first-order reaction A → products has a rate constant of 0.2 min⁻¹. The initial concentration of A is 2 mol/L. Find the concentration CA after 5 min.

k = 0.2 min⁻¹CA0 = 2 mol/Lt = 5 min
CA = mol/L
2.Easy
t (min)C/C₀ (%)100 min?

A first-order reaction has a half-life of 20 min. What percentage f of the reactant is still left after 100 min?

t½ = 20 mint = 100 min
f = %
3.Medium
t (min)X (%)t = ?90%

A second-order reaction (−rA = k·CA²) in a batch reactor has k = 0.2 L/(mol·min) and starts at 0.5 mol/L. How long does it take to reach 90% conversion? Find t.

k = 0.2 L/(mol·min)CA0 = 0.5 mol/LX = 90 %
t = min
4.Medium
t (min)X (%)t = ?75%

A zero-order reaction has k = 0.04 mol/(L·min) and starts at 0.8 mol/L. How long does it take to reach 75% conversion? Find t.

k = 0.04 mol/(L·min)CA0 = 0.8 mol/LX = 75 %
t = min
5.Hard
Tk35 °C0.0260 °C?

A reaction has a rate constant of 0.02 min⁻¹ at 35 °C and an activation energy of 75 kJ/mol. Find the rate constant k2 at 60 °C.

k1 = 0.02 min⁻¹T1 = 35 °CT2 = 60 °CEa = 75 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹
6.Hard
t (min)X (%)30 minX = ?

A first-order reaction has k = 0.01 min⁻¹ at 25 °C and an activation energy of 70 kJ/mol. The batch reactor is now run at 45 °C for 30 min. Find the conversion X reached.

k1 = 0.01 min⁻¹T1 = 25 °CEa = 70 kJ/molT2 = 45 °Ct = 30 minR = 8.314 J/(mol·K)
X = %

Answer key

  1. 1. CA = 0.7358 mol/L
  2. 2. f = 3.125 %
  3. 3. t = 90 min
  4. 4. t = 15 min
  5. 5. k2 = 0.1799 min⁻¹
  6. 6. X = 82.97 %

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