Phenyl acetate, an ester, reacts with water according to the...

Phenyl acetate, an ester, reacts with water according to the equation $$ \begin{array}{c} \mathrm{O} \\ \mathrm{CH}_{3} \mathrm{COC}_{6} \mathrm{H}_{5}+\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{CH}_{3} \mathrm{COH}+\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH} \end{array} $$ phenyl acetate $\quad$ acctic acid $\quad$ phenol The data in the table were collected for this reaction at $5^{\circ} \mathrm{C}$. (a) Plot the phenyl acetate concentration versus time, and describe the shape of the curve observed. (b) Calculate the rate of change of the phenyl acetate concentration during the period 15.0 seconds to 30.0 seconds and also during the period 75.0 seconds to 90.0 seconds. Why is one value smaller than the other?

Phenyl acetate, an ester, reacts with water according to the equation
$$
\begin{array}{c}
\mathrm{O} \\
\mathrm{CH}_{3} \mathrm{COC}_{6} \mathrm{H}_{5}+\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{CH}_{3} \mathrm{COH}+\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}
\end{array}
$$
phenyl acetate $\quad$ acctic acid $\quad$ phenol
The data in the table were collected for this reaction at $5^{\circ} \mathrm{C}$.
(a) Plot the phenyl acetate concentration versus time, and describe the shape of the curve observed.
(b) Calculate the rate of change of the phenyl acetate concentration during the period
15.0 seconds to 30.0 seconds and also during the period 75.0 seconds to 90.0 seconds. Why is one value smaller than the other?

Key Concepts

Reaction Rate Dependence on Reactant Concentration

Reaction rates generally depend on the concentration of the reactants. As a reaction proceeds and the concentration of a reactant decreases, the rate of the reaction usually slows down. This explains why the rate calculated over a later time interval might be smaller compared to an earlier interval when the reactant concentration is higher.

Rate of Change of Concentration

The rate of change of concentration, often expressed as the change in concentration over a specific time interval, is a quantitative measure of how fast a reaction proceeds. It is typically calculated by taking the difference between the concentrations at two time points and dividing by the time elapsed, providing an average reaction rate over that period.

Concentration-Time Graph

A concentration-time graph plots the concentration of a reactant or product against time. This visual representation helps in understanding the progress of the reaction, where the slope of the curve at any point reflects the rate of change of concentration, with a steeper slope indicating a faster reaction and a gentler slope indicating a slower reaction.

Reaction Kinetics

Reaction kinetics is the study of the rates at which chemical reactions occur and the factors that affect these rates. It involves analyzing how concentrations of reactants and products change over time, which can provide insights into the reaction mechanism and the influence of conditions such as temperature and catalyst presence.

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