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
CA​ (mol/L)r0.2r = ?CB​ = 0.2 mol/L

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

r = k·CBk = 0.5 s⁻¹CA = 0.2 mol/LCB = 0.2 mol/L
r = mol/(L·s)
2.Easy
t (min)C (mol/L)40 minC = ?

A zero-order reaction A → products has a rate constant of 0.01 mol/(L·min). The initial concentration of A is 2 mol/L. Find the concentration CA after 40 min.

k = 0.01 mol/(L·min)CA0 = 2 mol/Lt = 40 min
CA = mol/L
3.Medium
t (min)X (%)t = ?30%

A zero-order reaction has k = 0.04 mol/(L·min) and starts at 2 mol/L. How long does it take to reach 30% conversion? Find t.

k = 0.04 mol/(L·min)CA0 = 2 mol/LX = 30 %
t = min
4.Medium
t (min)X (%)t = ?99%

A first-order reaction in a batch reactor has k = 0.01 min⁻¹. How long does it take to reach 99% conversion? Find t.

k = 0.01 min⁻¹X = 99 %
t = min
5.Hard
Tk20 °C0.00240 °C0.0143

The rate constant of a reaction is 0.002 min⁻¹ at 20 °C and 0.0143 min⁻¹ at 40 °C. Find the activation energy Ea.

k1 = 0.002 min⁻¹T1 = 20 °Ck2 = 0.0143 min⁻¹T2 = 40 °CR = 8.314 J/(mol·K)
Ea = kJ/mol
6.Hard
Tk30 °Ck1​?5·k1​

A reaction has an activation energy of 70 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 = 70 kJ/molT1 = 30 °Ck2/k1 = 5R = 8.314 J/(mol·K)
T2 = °C

Answer key

  1. 1. r = 0.1 mol/(L·s)
  2. 2. CA = 1.6 mol/L
  3. 3. t = 15 min
  4. 4. t = 460.5 min
  5. 5. Ea = 75.07 kJ/mol
  6. 6. T2 = 48.65 °C

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