Chemical Kinetics(12th Grade > Chemistry ) Questions and Answers
Explanation:-
Answer: Option B. -> 0.39 g:
B
One hour 36 minutes, i.e., 96 minutes is 8 half lives
Hence the amount left over is 10028=100256=0.39g
Explanation:-
Answer: Option C. -> 7.5 hours:
C
Each half life would reduce the concentration to half of its original value. So, 99.9% completion takes place in 10 half-lives. Remember 210=1024 and 1/1024≈0.001
Hence time taken = 45 × 10 minutes = 450 minutes = 7.5 hours.
Explanation:-
Answer: Option B. -> 4:
B
For a second order kinetics of the reaction A → B we have rate = k[A]2. When conc. of A is doubled the rate of the reaction increases by a factor of 22(=4). Since rate of conversion of A = rate of formation of B. Hence rate of formation of B also increases 4 times.
Explanation:-
Answer: Option D. -> Value of k is independent of the initial concentration of A and B:
D
The order of the reaction is two. Option (b) and (c) apply to first order reactions. Options (a) is wrong since the rate of formation of C is half the rate of disappearance of A. Option (d) is always true since value of k for any order is independent of the initial concentration of the reactants.
Explanation:-
Answer: Option B. -> 10−1:
B
k=Ae−EaRT
Ea=2.303RT
∴kA=e−(2.303RTRT);kA=e−2.303
loge(kA)=logee−2.303
loge(kA)=−2.303 or 2.303log10(kA)=−2.303
log(kA)=−1;log(AK)=1
∴Ak=antilog1=10 or kA=110=10−1
Explanation:-
Answer: Option D. -> 40 mins:
D
If a reaction is 60% complete, 40% remains and if it is 84% complete, 16% remains.
For a first order reaction:
k=2.30320log10040=2.303tlog10016