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 (%)50 min?

A first-order reaction has a half-life of 10 min. What percentage f of the reactant is still left after 50 min?

t½ = 10 mint = 50 min
f = %
2.Easy
CA​ (mol/L)r0.5r = ?CB​ = 0.6 mol/L

The reaction A + B → C follows the rate law r = k·CB, with k = 0.002 s⁻¹. Find the reaction rate r when CA = 0.5 mol/L and CB = 0.6 mol/L.

r = k·CBk = 0.002 s⁻¹CA = 0.5 mol/LCB = 0.6 mol/L
r = mol/(L·s)
3.Medium
t (min)C (mol/L)5 minC = ?

A reaction with rate law −rA = k·CA² has k = 1 L/(mol·min) and starts at 1.5 mol/L. Find the concentration CA after 5 min.

k = 1 L/(mol·min)CA0 = 1.5 mol/Lt = 5 min
CA = mol/L
4.Medium
t (min)X (%)t = ?75%

A first-order reaction in a batch reactor has k = 0.02 min⁻¹. How long does it take to reach 75% conversion? Find t.

k = 0.02 min⁻¹X = 75 %
t = min
5.Hard
CA0​ (mol/L)r (mol/(L·s))run 10.20.01run 20.60.03n = ?

Two experiments measure the initial rate of A → products. With CA0 = 0.2 mol/L the rate is 0.01 mol/(L·s); with CA0 = 0.6 mol/L it is 0.03 mol/(L·s). Find the reaction order n with respect to A.

CA0,1 = 0.2 mol/Lr1 = 0.01 mol/(L·s)CA0,2 = 0.6 mol/Lr2 = 0.03 mol/(L·s)
n =
6.Hard
Tk30 °C0.140 °C0.259

The rate constant of a reaction is 0.1 min⁻¹ at 30 °C and 0.259 min⁻¹ at 40 °C. Find the activation energy Ea.

k1 = 0.1 min⁻¹T1 = 30 °Ck2 = 0.259 min⁻¹T2 = 40 °CR = 8.314 J/(mol·K)
Ea = kJ/mol

Answer key

  1. 1. f = 3.125 %
  2. 2. r = 0.0012 mol/(L·s)
  3. 3. CA = 0.1765 mol/L
  4. 4. t = 69.31 min
  5. 5. n = 1
  6. 6. Ea = 75.11 kJ/mol

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