Question

For a chemical reaction $R\to P$, the variation in the concentration (R) vs. time (t) plot is given.
(i) Predict the order of the reaction.
(ii) What is the slope of the curve?

Answer 1

From the graph, $\left[R\right]\propto -t\therefore \left[R\right]=-mt+c$
Where m is the slope.
Differentiating both sides,
$d\left[R\right]=-mdt\therefore \frac{-d\left[R\right]}{dt}=m$
i.e. Rate$=$m$=$constant
Here, rate of reaction does not depend on concentration of reactant.
(i) Therefore, it is a zero order reaction
(ii) $\therefore$ slope$=$K$=$rate constant.
because for zero order reaction,
Rate$=$K$=$ rate constant.