Question

Specific reaction rate is rate of reaction at unit concentration of reactants.
A. True
B. False

Answer 1

Hint: You might get confused with the name specific reaction rate. Specific reaction rate is also called rate constant or velocity constant. Now it is easier for you to answer.

Complete answer:
According to collision theory, the rate of the reaction is proportional to the number of molecular collisions taking place per second. Thus on increasing the concentration of the reactant number of collisions increases hence rate of the reaction increases.
Thus, for a general reaction:
$A\rightarrow Products$
$r\quad =\quad -dC_{ A }/dt\quad =\quad kC_{ A }$
Where, r = rate of reaction, $C_{ A }$ =concentration of the reactant A and k = rate constant.
If $C_{ A }$ = 1
then, r = k
We can say that at a given temperature, rate is equal to the rate constant of reaction when concentration of the reactant in unity. Thus rate constant is also known as specific reaction rate.
In the case of two reactants, the reaction may be written as:
$A\quad +\quad B\quad \rightarrow \quad Products$
$r\quad =\quad kC_{ A }C_{ B }$
Where all the terms have usual meaning. If $C_{ A }\quad =\quad C_{ B }\quad =\quad 1$ then r = k . Thus, rate constant is equal to rate of the reaction when the concentration of each of the reactants is unity.

Therefore, we can say that a specific rate constant at a given temperature may be defined as the rate of reaction when the molar concentration of each reactant is unity.

Hence, the correct answer is option A.

Note: The specific reaction rate (or rate constant) of a reaction depends upon
1. Temperature of reaction
2. Activation energy of reaction
3. Presence of absence of a catalyst