Question

For the reaction 2A(g) + B(g) → 2C(g), when the concentration of substance B in the reaction above is doubled, all other factors being held constant, it is found that the rate of the reaction remains unchanged. The most probable explanation for this observation is that

Answer 1

Substance B is not involved in the rate-determining step of the mechanism, but is involved in subsequent steps

Step-by-step explanation:

According to the law of mass action:-

The rate of the reaction is directly proportional to the active concentration of the reactant which each are raised to the experimentally determined coefficients which are known as orders. The rate is determined by the slowest step in the reaction mechanics.

Order of in the mass action law is the coefficient which is raised to the active concentration of the reactants. It is experimentally determined and can be zero, positive negative or fractional.

The order of the whole reaction is the sum of the order of each reactant which is raised to its power in the rate law.

Thus, Given that:- The change in the concentration of B does not affect the rate of the reaction. Hence, the order of B must be zero.

Hence, the answer is;- substance B is not involved in the rate-determining step of the mechanism, but is involved in subsequent steps