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 (%)12.5 min?

A first-order reaction has a half-life of 25 min. What percentage f of the reactant is still left after 12.5 min?

t½ = 25 mint = 12.5 min
f = %
2.Easy
CA​ (mol/L)r2r = ?CB​ = 1.2 mol/L

The reaction A + B → C follows the rate law r = k·CA, with k = 0.5 s⁻¹. Find the reaction rate r when CA = 2 mol/L and CB = 1.2 mol/L.

r = k·CAk = 0.5 s⁻¹CA = 2 mol/LCB = 1.2 mol/L
r = mol/(L·s)
3.Medium
t (min)C (mol/L)40 min0.8

In a first-order reaction the concentration of A falls from 1 mol/L to 0.8 mol/L in 40 min. Find the rate constant k.

CA0 = 1 mol/LCA = 0.8 mol/Lt = 40 min
k = min⁻¹
4.Medium
t (min)X (%)t = ?60%

A first-order reaction in a batch reactor has k = 0.01 min⁻¹. How long does it take to reach 60% conversion? Find t.

k = 0.01 min⁻¹X = 60 %
t = min
5.Hard
1/Tln kT = 60 °Cln 0.002ln A = ?Ea​ = 80 kJ/mol

A first-order reaction has a rate constant of 0.002 s⁻¹ at 60 °C and an activation energy of 80 kJ/mol. Find the pre-exponential factor A in the Arrhenius equation.

k = 0.002 s⁻¹T = 60 °CEa = 80 kJ/molR = 8.314 J/(mol·K)
A = s⁻¹
6.Hard
Tk35 °C0.0565 °C?

A reaction has a rate constant of 0.05 min⁻¹ at 35 °C and an activation energy of 120 kJ/mol. Find the rate constant k2 at 65 °C.

k1 = 0.05 min⁻¹T1 = 35 °CT2 = 65 °CEa = 120 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹

Answer key

  1. 1. f = 70.71 %
  2. 2. r = 1 mol/(L·s)
  3. 3. k = 0.005579 min⁻¹
  4. 4. t = 91.63 min
  5. 5. A = 6.994 × 10⁹ s⁻¹
  6. 6. k2 = 3.189 min⁻¹

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