Question

Calculate the order of reaction, $A \to $ Product, from the following data :

[A] (moles/L)	d [product)/dt (moles /L/s)
0.003	$10.0 \times 10^{-5}$
0.006	$5.0 \times 10^{-5}$
0.012	$2.5 \times 10^{-5}$

• A. 1
• B. -2
• C. -1
• D. 2

Answer 1

Answer: (C)

From $1^{\text {st }}$ reading

rate $=10.0 \times 10^{-5}=k[0.003]^{n} \,\,\,\,\,\, \dots(i)$

(where, $n$ is order of reaction)

From $2^{\text {nd }}$ reading

rate $=5.0 \times 10^{-5}=k[0.006]^{n} \,\,\,\,\,\, \dots(ii)$

On dividing (i) by (ii),

$\frac{10.0 \times 10^{-5}}{5.0 \times 10^{-5}}=\frac{k[0.003]^{n}}{k[0.006]^{n}}$

$ \Rightarrow 2=\left(\frac{1}{2}\right)^{n}$

$ \Rightarrow n=-1$