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

The reaction A + B → C follows the rate law r = k·C_A·C_B, with k = 0.2 L/(mol·s). Find the reaction rate r when C_A = 0.8 mol/L and C_B = 0.3 mol/L.

r = k·C_A·C_Bk = 0.2 L/(mol·s)C_A = 0.8 mol/LC_B = 0.3 mol/L

r = mol/(L·s)

2.Easy

A first-order reaction A → products has a rate constant of 0.1 min⁻¹. The initial concentration of A is 0.5 mol/L. Find the concentration C_A after 20 min.

k = 0.1 min⁻¹C_A0 = 0.5 mol/Lt = 20 min

C_A = mol/L

3.Medium

A second-order reaction (−r_A = k·C_A²) has k = 0.05 L/(mol·min) and an initial concentration of 1 mol/L. Find its first half-life t_½.

k = 0.05 L/(mol·min)C_A0 = 1 mol/L

t_½ = min

4.Medium

In a first-order reaction the concentration of A falls from 1 mol/L to 0.2 mol/L in 10 min. Find the rate constant k.

C_A0 = 1 mol/LC_A = 0.2 mol/Lt = 10 min

k = min⁻¹

5.Hard

A first-order reaction has k = 0.02 min⁻¹ at 20 °C and an activation energy of 60 kJ/mol. The batch reactor is now run at 35 °C for 10 min. Find the conversion X reached.

k₁ = 0.02 min⁻¹T₁ = 20 °CE_a = 60 kJ/molT₂ = 35 °Ct = 10 minR = 8.314 J/(mol·K)

X = %

6.Hard

A reaction has a rate constant of 0.005 min⁻¹ at 20 °C and an activation energy of 75 kJ/mol. Find the rate constant k₂ at 45 °C.

k₁ = 0.005 min⁻¹T₁ = 20 °CT₂ = 45 °CE_a = 75 kJ/molR = 8.314 J/(mol·K)

k₂ = min⁻¹

Answer key

1. r = 0.048 mol/(L·s)
2. C_A = 0.06767 mol/L
3. t_½ = 20 min
4. k = 0.1609 min⁻¹
5. X = 48.47 %
6. k₂ = 0.05612 min⁻¹

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