Question

The reaction between A and B is first order with respect to A and zero order with respect to B. Fill in the blanks in the following table:

Experiment	A/mol L−1	B/mol L−1	Initial rate/mol L−1 min−1
I	0.1	0.1	2.0 × 10−2
II	______	0.2	4.0 × 10−2
III	0.4	0.4	______
IV	______	0.2	2.0 × 10−2

Answer 1

Experiment	A/mol L−1	B/mol L−1	Initial rate/mol L−1 min−1
I	0.1	0.1	2.0 × 10−2
II	0.2	0.2	4.0 × 10−2
III	0.4	0.4	8.0 × 10−2
IV	0.1	0.2	2.0 × 10−2

The rate of the reaction is given by,

Rate = k [A]¹ [B]⁰

⇒ Rate = k [A]

From experiment I, we obtain

2.0 × 10⁻² mol L⁻¹ min⁻¹ = k (0.1 mol L⁻¹)

⇒ k = 0.2 min⁻¹

From experiment II, we obtain

4.0 × 10⁻² mol L⁻¹ min⁻¹ = 0.2 min⁻¹ [A]

⇒ [A] = 0.2 mol L⁻¹

From experiment III, we obtain

Rate = 0.2 min⁻¹ × 0.4 mol L⁻¹

= 0.08 mol L⁻¹ min⁻¹

= 8.0 × 10⁻² mol L⁻¹ min⁻¹

From experiment IV, we obtain

2.0 × 10⁻² mol L⁻¹ min⁻¹ = 0.2 min⁻¹ [A]

⇒ [A] = 0.1 mol L⁻¹