Question

For the irreversible process, A + B products, the rate is first–order w.r.t. A and second–order w.r.t. B. If 1.0 mol each of A and B introduced into a 1.0 L vessel, and the initial rate was 1.0 × 10–2mol L–1 s–1 , rate when half reactants have been turned into products is :

• A. 1.25 × 10–3mol L–1 s–1
• B. 1.0 × 10–2mol L–1 s–1
• C. 2.50 × 10–3mol L–1 s–1
• D. 2.0 × 10–2mol L–1 s–1

Answer 1

Answer: (A)

1.25 × 10–3mol L–1 s–1

Answer 2

$A + B\overset{\quad\quad}{\rightarrow}product$

$r = K\lbrack A\rbrack^{1}\lbrack B\rbrack^{2}$

$r_{1}\text{ = K }\lbrack 1\rbrack^{1}\text{ }\lbrack 1\rbrack^{2}\text{ } \text{= 1 }\text{×}\text{ 1}\text{0}^{\text{-2}}\ (\text{K = 1 }\text{×}\text{ 1}\text{0}^{\text{-2}})$

$r_{1}\text{ = K = 1 }\text{×}\text{ 1}\text{0}^{\text{-2}}\text{ }\text{×}\text{ = 1.25 }\text{×}\text{ 1}\text{0}^{\text{-3}}$