Question

1. From the stoichiometry of the reaction

   2 I– (aq) + H2O2 (aq) + 2 H3O+ (aq)  I2 (s) + 4 H2O (l) What can be said about rate law for this reaction? Explain the answer.

   a. The rate law is predicted to have a molecularity of five.

   b. The rate law is predicted to be second order in [I–].
   c. The rate law is predicted to be first-order in [H2O2].
   d. Statements a, b, and c are all true.
   e. The rate law cannot be determined from the stoichiometry of the reaction.

Answer 1

For a general chemical reaction,

According to rate law, the rate is

  

The overall order of reaction is the sum of power of concentration terms in rate law equation.

The reaction is said to be ath order with respect to A and bth order with respect to B.

For the given chemical equation, the Rate can be written as

  

From above rate equation, the rate is predicted to be 2nd order with respect to [I-]

The rate is predicted to be1st order with respect to [H2O2].

The molecularity of a reaction is the sum of stochiometric coefficients of all the reactants in chemical equation.

for general chemical equation,

  

For given chemical equation above, the molecularity is 2+1+2=5.

Therefore, option (d) Statements a, b, and c are all true. is correct.