Question

The kinetic study of hydrolysis of ethyl acetate is catalysed by an acid, and is followed by titrating a fixed volume of a reaction mixture with a standard alkali solution, at different intervals of time. The ester hydrolysis is acid catalysed. $V_0,V_t$ and $V_{\infty }$ are the volumes of alkali required at t = 0, t = t and $t=\infty$ respectively. Then, match the statements given in Column I with those in Column II.
$\begin{array}{cc}\text{Column I}& \text{Column II}\\ a)V_0\text{is proportional to}& \text{p) Total concentrations of acid initially}\\ & \text{present and concentration of acid}\\ & \text{formed at time t.}\\ b)V_t\text{is proportional to}& \text{q) Concentration of acid initially}\\ & \text{present as the catalyst}\\ c\left)\right(V_{\infty }-V_t)\text{is proportional to}& \text{r) Concentration of acid formed after}\\ & \text{the completion of reaction}\\ d\left)\right(V_{\infty }-V_0)\text{is proportional to}& \text{s) Concentration of ester remaining}\\ & \text{at time t.}\end{array}$

• A. (a-q, b-p, c-s, d-r)
• B. (a-p, b-p, c-s, d-r)
• C. (a-q, b-q, c-s, d-r)
• D. (a-q, b-q, c-r, d-s)

Answer 1

The correct option is A (a-q, b-p, c-s, d-r)

$Ester\stackrel{H^{+}}{\to }ethanol+aceticacid$
$a_{0}00V_0$
$a_0-xxx{V}_t$
$0a_0{a}_0{V}_{\infty }$
$volume\propto moles$
1.
$V_{\infty }-V_0=2a_0-a_0=a_0$
this represents the amount of acid formed after the completion of the reaction.
2.
$V_{\infty }-V_t=2a_0-(a_0+x)=a_0-x$
Concentration of ester remaining at time t.
3.
$V_0$
Concentration of acid initially present as the catalyst
4.
$V_t$
Total concentration of the acid initially present and the concentration of acid formed at time t.