CBSE Class 12 Chemistry Chemical Kinetics Worksheet Set D

Question. (i) What is the order of the reaction whose rate constant has same units as the rate of reaction ?
(ii) For a reaction A + H₂O → B; Rate ∝ [A]. What is the order of this reaction?
Answer. (i) Zero order
(ii) Pseudo-first order

Question. State a condition under which a bimolecular reaction is kinetically first order reaction. 
Answer. Let us take a bimolecular reaction :
A + B → Product
Rate = k [A] [B]
When concentration of [B] is taken in excess then rate law will become:
Rate = k [A]
where, k = constant
The rate depends only on one of the reactant as there is negligible change in its concentration so it is bimolecular but is of first order.

Question. (i) For which reaction, the rate of reaction does not decrease with time?
(ii) What is the order of photochemical reaction?
Answer. (i) For zero order reaction the rate of reaction does not decrease with time because it does not depend on concentration of reactants.
(ii) Zero Order reaction.

Question. Explain the following terms:
(i) Rate constant (k)
(ii) Half-life period of reaction (t_1/2).
Answer. (i) Rate constant (k): Rate constant is rate of the reaction when the concentration of reactants is unity.
(ii) Half-life period of a reaction (t_1/2): Half-life of a reaction is the time in which the concentration of a reactant is reduced to half of its original value.

Question. (i) Explain why H₂ and O₂ do not react at room temperature.
(ii) Write the rate equation for the reaction
A₂ + 3B₂ → 2C, if the overall order of the reaction is zero. 
Answer. (i) Due to high activation energy of the reaction between O₂ and H₂.
(ii) Rate = k [A₂]⁰[B₂]⁰

Question. (i) The rate of reaction decreases with the progress of reaction. Why?
(ii) Reactions having molecularity more than three occur rarely. Why? 
Answer. (i) The rate of reaction depends on the concentration of reactants. Since, the concentration of reactants decreases with time, so rate of reaction also decreases.
(ii) It is because of the fact that collision of more than three molecules is not possible at a time.

Question. (i) What is the order of the reaction whose rate constant has same units as the rate of reaction ?
(ii) For a reaction A + H₂O → B; Rate ∝ [A].
What is the order of this reaction ?
Answer. (i) Zero order 
(ii) Pseudo-first order

Please click on below link to download CBSE Class 12 Chemistry Chemical Kinetics Worksheet Set A