State the differences between molecularity and order of a reaction
Answers
The order of reaction is obtained from the rate law of the reaction. The difference between molecularity and order of reaction is that molecularity is a theoretical concept whereas order of reaction is determined experimentally
DEFINITION: Order Sum of the exponents of the molar concentration(s) in the rate law expression. Molecularity The number of atoms, ions, molecules that must collide with one another simultaneously to result into a chemical reaction.
Order need not be a whole number. It can be fractional or zero. Molecularity is always a whole number.
Order can be determined experimentally only. Molecularity can be calculated by adding the no. of molecules in the slowest step (directly by looking at the balanced equation).
Order is applicable to simple + elementary reactions. Molecularity is applicable to simple reactions. No significance in determining molecularity of a complex reaction.
Order cannot be determined by looking at the stoichiometric coefficients. Molecularity can be determined by looking at the stoichiometric coefficients.