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)r1r = ?CB​ = 0.2 mol/L

The reaction A + B → C follows the rate law r = k·CA²·CB, with k = 0.1 L²/(mol²·s). Find the reaction rate r when CA = 1 mol/L and CB = 0.2 mol/L.

r = k·CA²·CBk = 0.1 L²/(mol²·s)CA = 1 mol/LCB = 0.2 mol/L
r = mol/(L·s)
2.Easy
t (min)C (mol/L)t½​ = ?C0​/2

A first-order reaction has a rate constant of 0.15 min⁻¹. Find its half-life t½.

k = 0.15 min⁻¹
t½ = min
3.Medium
t (min)C (mol/L)40 min0.25

In a first-order reaction the concentration of A falls from 0.5 mol/L to 0.25 mol/L in 40 min. Find the rate constant k.

CA0 = 0.5 mol/LCA = 0.25 mol/Lt = 40 min
k = min⁻¹
4.Medium
t (min)C (mol/L)t½​ = ?C0​/2

A second-order reaction (−rA = k·CA²) has k = 0.8 L/(mol·min) and an initial concentration of 0.5 mol/L. Find its first half-life t½.

k = 0.8 L/(mol·min)CA0 = 0.5 mol/L
t½ = min
5.Hard
Tk40 °C0.00550 °C?

A reaction has a rate constant of 0.005 min⁻¹ at 40 °C and an activation energy of 90 kJ/mol. Find the rate constant k2 at 50 °C.

k1 = 0.005 min⁻¹T1 = 40 °CT2 = 50 °CEa = 90 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹
6.Hard
1/Tln kT = 50 °Cln 0.001ln A = ?Ea​ = 40 kJ/mol

A first-order reaction has a rate constant of 0.001 s⁻¹ at 50 °C and an activation energy of 40 kJ/mol. Find the pre-exponential factor A in the Arrhenius equation.

k = 0.001 s⁻¹T = 50 °CEa = 40 kJ/molR = 8.314 J/(mol·K)
A = s⁻¹

Answer key

  1. 1. r = 0.02 mol/(L·s)
  2. 2. t½ = 4.621 min
  3. 3. k = 0.01733 min⁻¹
  4. 4. t½ = 2.5 min
  5. 5. k2 = 0.01457 min⁻¹
  6. 6. A = 2924 s⁻¹

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