Question

$aP + bQ \to$ Products, when $[P]$ is doubled keeping $[Q]$ constant rate increases $2$ times, when $[P]$ is constant and $[Q]$ is doubled, rate increases four times. The overall order is

• A. 1
• B. 2
• C. 3
• D. 2.5

Answer 1

Answer: (C)

3

Answer 2

For a reaction,
$aP + bQ \to$ Products
$r = k(P]^x[Q]^y$? ? ?? ? ? ? .... (i)
$2r = k[2P]^x[Q]^y$? ? ? ...... (ii)
$4r = k[P]^x[2Q]^y$? ? ? ...... (iii)
On dividing equation (ii) by (i), we get $2 = 2^x \Rightarrow x = 1$
On dividing equation (iii) by (i), we get $4 = 2^y \Rightarrow y = 2$
$therefore$ Overall order = $x + y = 1 + 2 = 3$