Question

The sum of the powers of the concentration terms that occur in the rate equation is called:
A.Rate
B.Molecular
C.Rate constant
D.Order

Answer 1

To solve this question, we must first discuss the rate law and the different characteristics of the rate law. Once we do this, we can derive a relation between the partial orders and the complete order of the reaction.

Complete Step-by-Step Answer:
Before we move forward with the solution of the given question, let us first understand some important basic concepts.
Rate equation for rate law can be defined as an equation which establishes a relation between the rate at which the given reaction proceeds to the product of the concentrations of the reactants raised to the power to which they contribute to the rate of the reaction. This law can be mathematically represented as:
For the given reaction: $A + B \to C + D$ ,
Rate Law: ${\nu _0} = k{[A]^x}{[B]^y}$
Where ${\nu _0}$ is the rate of the reaction, k is the reaction constant, [A] and [B] are the concentrations of the reactants, x and y are the partial orders of the reaction for A and B respectively. The sum of these partial orders gives us the overall order of the reaction.
From this, we can conclude that the sum of the powers of the concentration terms that occur in the rate equation is called the order of the reaction.
Hence, Option D is the correct option

Note: In a dilute solution, an elementary reaction (a reaction which has one single step that is the transition step of the reaction) is empirically found to be obeying the law of mass action. According to this law, the rate of the reaction depends only on the concentrations of the reactants, which are raised to the powers of their stoichiometric coefficients.