Question

The rate and the rate constants of the reaction, \[\ce{A + 2B -> C + D}\] are 8 × 10⁻³ mol dm⁻³ s⁻¹ and 2 × 10⁻³ s⁻¹ respectively. The concentrations of A and B are 4 mol dm⁻³ each. The overall order of the reaction is ____________.

Options

• 0

• 1

• 2

• 3

Answer 1

The rate and the rate constants of the reaction, \[\ce{A + 2B -> C + D}\] are 8 × 10⁻³ mol dm⁻³ s⁻¹ and 2 × 10⁻³ s⁻¹ respectively. The concentrations of A and B are 4 mol dm⁻³ each. The overall order of the reaction is 1.

Explanation:

The rate law is, rate = k[A]^x[B]^y

where, rate = 8 × 10⁻³ mol dm⁻³ s⁻¹,

rate constant k = 2 × 10⁻³ s⁻¹

Concentration of A = [A] = 4 mol dm⁻³;

Concentration of B = [B] = 4 mol dm⁻³

Substituting values in the rate law,

8 × 10⁻³ M s⁻¹ = 2 × 10⁻³ s⁻¹ × [4 mol dm⁻³]^x × [4 mol dm⁻³]^y

∴ `(8 xx 10^-3)/(2 xx 10^-3)` = [4]^x+y

∴ 4 = [4]^x+y

∴ x + y = 1