Question

$2N_2{O}_5\rightleftharpoons 4N{O}_2+O_2$
Rate of reaction measured in terms of $N{O}_2$ is ${10}^{-3}$ mole $L^{-1}{S}^{-1}$. Calculate rate of reaction expressed in terms of $N_2{O}_5$.

Answer 1

Given equation ${2N}_2{O}_5=4{NO}_2+O_2$

Rate of disappearance of $N_2{O}_5\times \frac{1}{2}=\frac{1}{4}\times$ rate of formation of ${NO}_2$

Disappearance of $N_2{O}_5=2\times \frac{1}{4}\times 2.8\times {10}^{-3}=1.4\times {10}^{-3}$

However, we still write the rate of disappearance as a negative number.

Also, if you think about it a negative rate of disappearance is essentially a positive rate of appearance.