# Distinguish Between Molecularity and Order of Reaction. - Chemistry

Distinguish Between

Distinguish between : Order and Molecularity of reaction

Distinguish between molecularity and order of reaction.

#### Solution 1

 ORDER OF A REACTION MOLECULARITY OF A REACTION It is sum of the concentration terms on which the rate of reaction actually depends or it is the sum of the exponents of the concentrations in the rate law equation. It is the number of atoms, ions or molecules that must collide with one another simultaneously so as to result into a chemical reaction. It need not be a whole number i.e. it can be fractional as well as zero. It is always a whole number. It can be determined experimentally only and cannot be calculated. It can be calculated by simply adding the molecules of the slowest step. It is for the overall reaction and no separate steps are written to obtain it. The overall molecularity of a complex reaction has no significance. It is the only slowest step whose molecularity has significance for the overall reaction. Even the order of a simple reaction may not be equal to the number of molecules of the reactants as seen from the unbalanced equation. For simple reactions, the molecularity can usually be obtained from the Stoichiometry of the equation. It may be an integer, fraction or zero It is always an integer and never afraction or zero.

#### Solution 2

 Order of reaction Molecularity 1. It is an experimentally determined property. It is a theoretical entity. 2. It is the sum of powers of the concentration terms of reactants that appear in the rate equation. It is the number of reactant molecules taking part in an elementary reaction. 3. It may be an integer, fraction or zero. It is integer. 4. It is not based on a balanced chemical equation. It is based on a balanced chemical equation.
Concept: Temperature Dependence of Reaction Rates
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#### APPEARS IN

SCERT Maharashtra Question Bank 12th Standard HSC Chemistry Maharashtra State Board 2021
Chapter 6 Chemical Kinetics
Short answer questions (Type- I) | Q 2