Question

Find the unit of the rate constant of a reaction represented with a rate equation, rate = $k [A]^{1/2} [B]^{3/2}$

• A. $mol^{-1} \, L \, s^{-1}$
• B. $s^{-1}$
• C. $mol \, L ^{-1} \, s^{-1}$
• D. $mol^{-2} \, L^2 \, s^{-1}$
• E. $mol^{-3} \, L^3 \, s^{-1}$

Answer 1

Answer: (A)

$\because$ Rate $(r)=k$ [concentration] $^{n}$

$\therefore k=\frac{\text { rate }}{[\text { concentration }]^{n}}$

or, $k=\frac{\left[ mol\, L ^{-1}\right] \cdot s ^{-1}}{\left[ mol\, L ^{-1}\right]^{\frac{1}{2}} \cdot\left[ mol\, L ^{-1}\right]^{\frac{3}{2}}}$

$k=\frac{\left[ mol\, L ^{-1}\right] \cdot s ^{-1}}{\left[ mol\, L ^{-1}\right]^{2}}$

$k= mol ^{-1} L\, s ^{-1}$