Question

What is the initial rate of reaction?

Answer 1

Hint: As we know that for deriving rate laws, the method of initial rate is mostly used technique. In simple words we can say the initial rate is the rate at the very beginning of a reaction.

Complete answer:
- We can say that the instantaneous rate at the start of the reaction (that is when t=0) is called as Initial rate. As the name suggests, the method includes the measurement of the Initial rate of a reaction.
- This method involves measuring of rate laws at very short times before any changes in concentration takes place. Let’s consider a reaction:
\[A+2B\to 3C\]
Here, we can write the rate law as:
\[r=k{{\left[ A \right]}^{a}}{{\left[ B \right]}^{b}}\]
-If the initial concentrations of A and B are known, and initial rates are measured, then the rate constant k, and the exponents ‘a’ and ‘b’ are the only unknowns in the rate law. Basically, we measure the initial rate for some different sets of concentrations and then compare the initial rate.
- It is found that in the curve of reactant concentration versus time, the Initial rate is generally equal to the negative of the slope.

Note: - It is found that rate of reaction can be affected by several factors like: concentration, temperature, presence of a catalyst, phase of the reactants.
- We should note the difference between initial rate and instantaneous rate. Instantaneous rate is the rate at a particular time, whereas initial rate is the rate at the very beginning of a reaction.