Question

Difference between order of reaction and molecularity

Answer 1

Answer:

Order is an experimental concept. Actually , order of a reaction means sum of the powers of the reactant concentration expressed in the rate law expression.But, it can be obtained experimentally.It can be fractional or can be zero or  integers.It may or may not be equal to the stoiciometric representation of the reactants present in a balanced chemical reaction.

2A+3B=2C (let us consider this equation)

rate =k[A]^m [B]^n  so order wrt A  is m and order wrt B is n. Overall order is(m+n)

MOLECULARITY:it is a theoritical concept.It means  the no. of molecules which are  taking part in an single step or elementary step reaction.so its value must be +ve integers .it can not assign -ve or fractional or zero values. If areaction is multistep reaction then its molecularity cannot be obtained from balanced chemical equation.

these all are the differences.

Explanation:

Answer 2

⇒ Molecularity :

1. It is defined as the number of molecules of reactant taking part in a reaction .
2. Ex; $NH_{4} NO_{2} \frac{Δ}{---- > } N_{2} +2H_{2}O$ .
3. It is a theoretical value .
4. It is always a whole number . It can neither be Zero nor Fractional .
5. It is derived from Rate Determining step in the mechanism of reaction .

⇒ Order :

1. It is defined as the sum of the power of concentration terms that appear in rate low .
2. Ex;   NH_{4} NO_{2} \frac{Δ}{---- > } N_{2} +2H_{2}O                       Rate = k[NH_{4} NO_{2}], order =1 .
3. It is an experimental value .
4. It may be Zero, Fractional or Integer .
5. It is derived from Rate expression .