Question

For the reaction 2 A + B → 3C + D
Which of the following does not express the reaction rate ?
(a) - d[B]/dt (b) d[D]/dt
(c) – 1/2 d[A]/dt (d) - 1/3 d[C]/dt

Answer 1

For the reaction 2 A + B → 3C + D the following does not express the reaction rate:

(d) - 1/3 d[C]/dt

-The rate of reaction is expressed as the disappearance of reactants or the appearance of products divided by the stoichiometric coefficients

-As reactants are disappearing, a negative sign is used for them and products are appearing so they remain positive

- So for the reaction 2 A + B → 3C +D, option (a) - d[B]/dt, (b) d[D]/dt & (c) – 1/2 d[A]/dt are correctly describing rate of reaction

-But option (d)- 1/3 d[C]/dt does not represent the correct rate of reaction as it has a negative sign