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)t½​ = ?C0​/2

A first-order reaction has a rate constant of 0.2 min⁻¹. Find its half-life t½.

k = 0.2 min⁻¹
t½ = min
2.Easy
CA​ (mol/L)r0.2r = ?CB​ = 1 mol/L

The reaction A + B → C follows the rate law r = k·CA·CB, with k = 0.5 L/(mol·s). Find the reaction rate r when CA = 0.2 mol/L and CB = 1 mol/L.

r = k·CA·CBk = 0.5 L/(mol·s)CA = 0.2 mol/LCB = 1 mol/L
r = mol/(L·s)
3.Medium
t (min)X (%)t = ?80%

A first-order reaction in a batch reactor has k = 0.01 min⁻¹. How long does it take to reach 80% conversion? Find t.

k = 0.01 min⁻¹X = 80 %
t = min
4.Medium
t (min)X (%)t = ?80%

A second-order reaction (−rA = k·CA²) in a batch reactor has k = 0.05 L/(mol·min) and starts at 2 mol/L. How long does it take to reach 80% conversion? Find t.

k = 0.05 L/(mol·min)CA0 = 2 mol/LX = 80 %
t = min
5.Hard
Tk20 °Ck1​?10·k1​

A reaction has an activation energy of 70 kJ/mol. At 20 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 10 times faster?

Ea = 70 kJ/molT1 = 20 °Ck2/k1 = 10R = 8.314 J/(mol·K)
T2 = °C
6.Hard
Tk35 °C0.0255 °C?

A reaction has a rate constant of 0.02 min⁻¹ at 35 °C and an activation energy of 100 kJ/mol. Find the rate constant k2 at 55 °C.

k1 = 0.02 min⁻¹T1 = 35 °CT2 = 55 °CEa = 100 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹

Answer key

  1. 1. t½ = 3.466 min
  2. 2. r = 0.1 mol/(L·s)
  3. 3. t = 160.9 min
  4. 4. t = 40 min
  5. 5. T2 = 45.55 °C
  6. 6. k2 = 0.2159 min⁻¹

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