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.

New worksheetPractise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
t (min)C/C₀ (%)36 min?

A first-order reaction has a half-life of 12 min. What percentage f of the reactant is still left after 36 min?

t½ = 12 mint = 36 min
f = %
2.Easy
CA​ (mol/L)r0.4r = ?CB​ = 2 mol/L

The reaction A + B → C follows the rate law r = k·CA·CB², with k = 0.02 L²/(mol²·s). Find the reaction rate r when CA = 0.4 mol/L and CB = 2 mol/L.

r = k·CA·CB²k = 0.02 L²/(mol²·s)CA = 0.4 mol/LCB = 2 mol/L
r = mol/(L·s)
3.Medium
t (min)X (%)t = ?50%

A second-order reaction (−rA = k·CA²) in a batch reactor has k = 0.2 L/(mol·min) and starts at 2 mol/L. How long does it take to reach 50% conversion? Find t.

k = 0.2 L/(mol·min)CA0 = 2 mol/LX = 50 %
t = min
4.Medium
t (min)C (mol/L)t½​ = ?C0​/2

A second-order reaction (−rA = k·CA²) has k = 1 L/(mol·min) and an initial concentration of 0.8 mol/L. Find its first half-life t½.

k = 1 L/(mol·min)CA0 = 0.8 mol/L
t½ = min
5.Hard
Tk20 °C0.00260 °C?

A reaction has a rate constant of 0.002 min⁻¹ at 20 °C and an activation energy of 70 kJ/mol. Find the rate constant k2 at 60 °C.

k1 = 0.002 min⁻¹T1 = 20 °CT2 = 60 °CEa = 70 kJ/molR = 8.314 J/(mol·K)
k2 = min⁻¹
6.Hard
Tk20 °Ck1​?4·k1​

A reaction has an activation energy of 40 kJ/mol. At 20 °C it is too slow. To what temperature T2 (in °C) must it be heated to make it 4 times faster?

Ea = 40 kJ/molT1 = 20 °Ck2/k1 = 4R = 8.314 J/(mol·K)
T2 = °C

Answer key

  1. 1. f = 12.5 %
  2. 2. r = 0.032 mol/(L·s)
  3. 3. t = 2.5 min
  4. 4. t½ = 1.25 min
  5. 5. k2 = 0.0629 min⁻¹
  6. 6. T2 = 47.05 °C

Full step-by-step solutions: practise this topic on examproblems.com.