Question

One litre of 2M acetic acid is mixed with one litre of 3M ethyl alcohol to form ester $C{H}_{3}COOH+C_2{H}_{5}OH\iff C{H}_{3}COO{C}_2{H}_5+H_{2}O$. The decrease in the initial rate if each solution is diluted by an equal volume of water would be

• A. 0.5 times
• B. 2 times
• C. 4 times
• D. 0.25 times

Answer 1

The correct option is C 4 times

When each solution is diluted by equal volume of water, the concentration of each chemical is reduced to half the original.
We assume that this is an elementary reaction which leads to the conclusion that the order of this reaction would be 2.
The rate equation is $v=k[C{H}_{2}COOH{]}^1\times [C_2{H}_{5}OH{]}^1$. Hence the rate decreases by a factor of $\frac{1}{2}\times \frac{1}{2}=\frac{1}{4}$.
Thus the rate after dilution will be 4 times lesser than earlier rate.