Question

The plot of concentration of a reactant vs time for a chemical reaction is shown below:

The order of this reaction with respect to the reactant is:

• A. 0.0
• B. 1
• C. 2
• D. not possible to determine from this plot

Answer 1

The correct option is A 0.0

Consider a zero order reaction.
$A\to P$
At t = 0, concentration is $C_0$.
At t = t, concentration is $C_t$.
$\therefore \frac{-dC}{dt}=kdC=-kdt$
Upon integration,
$[C{]}_{C_0}^{C_t}=-k[t{]}_0^t{C}_t=C_0-kt$
Comparing this to straight line equation $y=mx+c{C}_t=-kt+C_0$
$\text{Slope}=-k$ (decreasing slope)
$\text{Intercept}=C_0$
Since the given slope is in negative, rate is zero order.