Question

Explain the method of initial rates to determine rate of law and order of reaction

Answer 1

Hint: As we all know that initial rate of reaction is the instantaneous rate at the start of the reaction. This initial rate is equal to the negative of the slope of the curve of reactant concentration the graph reactant concentration versus time at \[t = 0\]

Complete answer:
Before we get into the solution of the question, we need to be clear of the method of initial reaction. Therefore, the method of initial reaction is, the order of that reactant concentration in the rate law can be determined by observing how the reaction rate varies as the concentration of that one reactant is varied. This method is repeated for each reactant until all the orders are determined.
Now, when we look at the mathematical relationship of reaction rate with reactant concentrations is known as the rate law. The following is the hypothetical reaction,
$aA + bB \to cC$
The rate of law can be expressed as follows:
$Rate = k{\left[ A \right]^y}{\left[ B \right]^z}$
The reaction order is the sum of the concentration term exponent in a rate law equation
Let us take an example for understanding the concept better,
$N{O_2}(g) + CO(g) \to NO(g) + C{O_2}(g)$
The rate law is determined experimentally as:
$Rate = k{\left[ {N{O_2}} \right]^2}$
Therefore, we can say that the overall reaction order for this reaction is in second order that is the sum of all exponents in the rate law is $2$ but it is zero order for $CO$ second order for $N{O_2}$
The reaction order is most often a whole number as $0,1,or,2$. It is rarely when the reaction order can take value in fraction or negative numbers.

Note: these kinds of questions which are basically simply are often mistaken to be difficult. So always understanding the concept well helps in solving these kinds of questions. The main thing that has to be followed is the equations and method of initial rate. This way it becomes simple.