What do you understand by the ‘order of a reaction’? Identify the reaction order from each of the following units of reaction rate constant:
(i) L-1 mol-1
(ii) L mol-1 s-1
The sum of the powers of the concentrations of the reactants of a chemical reaction in the rate law expression is called the order of that chemical reaction.
Rate = k [A]x [B]y
Order of reaction = x + y
The orders of reaction for the following units are:
(i) L-1 mol s-1: Zero order
(ii) L mol-1s-1: Second order
A reaction is second order in A and first order in B.
(i) Write the differential rate equation.
(ii) How is the rate affected on increasing the concentration of A three times?
(iii) How is the rate affected when the concentrations of both A and B are doubled?
A reaction is second order in A and first order in B.
Differential rate equation:-
(ii) On increasing the concentration of A three times i.e. 3A:
Rate = k[3A]2[B]=9k[A]2[B]=9(Rate) , i.e. 9 times the initial rate.
(iii) On increasing the concentration of A and B as 2A and 2B:
Rate1= k[2A]2[2B]=k(4x2)[A]2[B]=8k[A]2[B]=8 (Rate) , i.e. 8 times the initial rate.
For a first order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of reaction.
A first order reaction takes 40 minutes for 30% decomposition. Calculate t1/2 for this reaction.
(Given log 1.428 = 0.1548)
A --> P
T=0 a 0
T=t (a-x) x
Now, it takes 40 min for 30% decomposition i.e. reactant left after 40 min is 70% of its initial concentration.
So,
The following data were obtained during the first-order thermal decomposition of SO2Cl2 at a constant volume:
SO2Cl2(g)---> SO2(g) + Cl2(g)
|
Experiment |
Time/s-1 |
Total pressure/atm |
|
1 |
0 |
0.4 |
Calculate the rate constant. (Given : log 4 = 0.6021, log 2 = 0.3010)
The thermal decomposition of SO2Cl2 at a constant volume is represented by the following equation: 
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