Question

While studying the decomposition of gaseous $N_2{O}_5$, it is observed that a plot of logarithum of its partial pressure versus time is linear. This shows that the decomposition of $N_2{O}_5$ follows:

• A. second order kinetics
• B. first order kinetics
• C. zero order kinetics
• D. pseudo first order kinetics

Answer 1

Answer: (B)

first order kinetics

While studying the decomposition of gaseous $N_2{O}_5$, it is observed that a plot of logarithm of its partial pressure versus time is linear. This shows that the decomposition of $N_2{O}_5$ follows first order kinetics.
$k=\frac{2.303}{t}log\frac{A_0}{A_t}ork=\frac{2.303}{t}log\frac{a}{a-x}$
where $A_0$ is the initial concentration of the reactants and $A_t$ is the concentration of the reactants after time t. Therefore,
$log{A}_t=log{A}_0-\frac{k}{2.303}t$ [y = mx + c, Equation of straight line where m = slope = $\frac{-k}{2.303}$ Integrcept (c) = $log{A}_0$
For the given case, the graph is between logarithm of partial pressure and time. From the slope of the graph, rate constant for the reaction can be calculated.