Question

Consider following two reactions
$A \longrightarrow $ Product $-\frac{d[A]}{d t}=k_{1}[A]^{0}$
$B \longrightarrow $ Product $-\frac{d[B]}{d t}=k_{2}[B]$
$k_{1}$ and $k_{2}$ are expressed in terms of molarity $\left( mol L ^{-1}\right)$ and time $\left( s ^{-1}\right) as :$

• A. $s ^{-1}, M s ^{-1} L ^{-1}$
• B. $M s ^{-1}, M s ^{-1}$
• C. $s ^{-1}, M ^{-1} s ^{-1}$
• D. $M s ^{-1}, s ^{-1}$

Answer 1

Answer: (D)

Unit of rate constant $k=\frac{1}{\text { Time }} \cdot \frac{1}{(\text { conc. })^{n-1}}$

For $ k_{1} \quad n=0 \quad k=\frac{1}{t} \cdot \frac{1}{(\operatorname{con} c)^{0-1}}$ hence

conc $\cdot t^{-1} \equiv M \cdot \sec ^{-1}$

$k_{2} n=1 k=\frac{1}{t} \cdot \frac{ 1}{(\operatorname{con} c)^{1-1}}=\frac{1}{t}=s^{-1}$