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/C₀ (%)60 min?

A first-order reaction has a half-life of 12 min. What percentage f of the reactant is still left after 60 min?

t½ = 12 mint = 60 min
f = %
2.Easy
t (min)C (mol/L)t½​ = ?C0​/2

A first-order reaction has a rate constant of 0.05 min⁻¹. Find its half-life t½.

k = 0.05 min⁻¹
t½ = min
3.Medium
t (min)C (mol/L)10 min0.45

In a first-order reaction the concentration of A falls from 1.5 mol/L to 0.45 mol/L in 10 min. Find the rate constant k.

CA0 = 1.5 mol/LCA = 0.45 mol/Lt = 10 min
k = min⁻¹
4.Medium
t (min)X (%)t = ?75%

A zero-order reaction has k = 0.05 mol/(L·min) and starts at 1.5 mol/L. How long does it take to reach 75% conversion? Find t.

k = 0.05 mol/(L·min)CA0 = 1.5 mol/LX = 75 %
t = min
5.Hard
t (min)X (%)15 minX = ?

A first-order reaction has k = 0.002 min⁻¹ at 25 °C and an activation energy of 80 kJ/mol. The batch reactor is now run at 35 °C for 15 min. Find the conversion X reached.

k1 = 0.002 min⁻¹T1 = 25 °CEa = 80 kJ/molT2 = 35 °Ct = 15 minR = 8.314 J/(mol·K)
X = %
6.Hard
Tk30 °Ck1​?5·k1​

A reaction has an activation energy of 80 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 = 80 kJ/molT1 = 30 °Ck2/k1 = 5R = 8.314 J/(mol·K)
T2 = °C

Answer key

  1. 1. f = 3.125 %
  2. 2. t½ = 13.86 min
  3. 3. k = 0.1204 min⁻¹
  4. 4. t = 22.5 min
  5. 5. X = 8.195 %
  6. 6. T2 = 46.19 °C

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