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)r0.4r = ?CB​ = 0.2 mol/L

The reaction A + B → C follows the rate law r = k·CA², with k = 0.1 L/(mol·s). Find the reaction rate r when CA = 0.4 mol/L and CB = 0.2 mol/L.

r = k·CA²k = 0.1 L/(mol·s)CA = 0.4 mol/LCB = 0.2 mol/L
r = mol/(L·s)
3.Medium
t (min)X (%)t = ?95%

A first-order reaction in a batch reactor has k = 0.05 min⁻¹. How long does it take to reach 95% conversion? Find t.

k = 0.05 min⁻¹X = 95 %
t = min
4.Medium
t (min)C (mol/L)10 minC = ?

A reaction with rate law −rA = k·CA² has k = 0.05 L/(mol·min) and starts at 0.5 mol/L. Find the concentration CA after 10 min.

k = 0.05 L/(mol·min)CA0 = 0.5 mol/Lt = 10 min
CA = mol/L
5.Hard
Tk25 °C0.00240 °C0.0114

The rate constant of a reaction is 0.002 min⁻¹ at 25 °C and 0.0114 min⁻¹ at 40 °C. Find the activation energy Ea.

k1 = 0.002 min⁻¹T1 = 25 °Ck2 = 0.0114 min⁻¹T2 = 40 °CR = 8.314 J/(mol·K)
Ea = kJ/mol
6.Hard
CA0​ (mol/L)r (mol/(L·s))run 10.250.02run 211.28n = ?

Two experiments measure the initial rate of A → products. With CA0 = 0.25 mol/L the rate is 0.02 mol/(L·s); with CA0 = 1 mol/L it is 1.28 mol/(L·s). Find the reaction order n with respect to A.

CA0,1 = 0.25 mol/Lr1 = 0.02 mol/(L·s)CA0,2 = 1 mol/Lr2 = 1.28 mol/(L·s)
n =

Answer key

  1. 1. t½ = 3.466 min
  2. 2. r = 0.016 mol/(L·s)
  3. 3. t = 59.91 min
  4. 4. CA = 0.4 mol/L
  5. 5. Ea = 90.07 kJ/mol
  6. 6. n = 3

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