Half life
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The rate constant for the first order decomposition of H_{2}O_{2} is given by the following equation:
log k = 14.34 − 1.25 × 10^{4 }K/T
Calculate E_{a} for this reaction and at what temperature will its halfperiod be 256 minutes?
The half  time period of a radioactive element is 140 days. After 560 days, one gram of the element will reduce to
12 g
14 g
116 g
18 g
The rate constant for the first order reaction is 60 s^{1}. How much time will it take to reduce the concentration of the reactant to 1/16th value?
4.6 x 10^{2} sec
5.1 x 10^{2} sec
4.6 x 10^{4} sec
4.6 x 10^{2} min
 164 of the initial the concentration
 112 of the initial the concentration
 132 of the initial the concentration
 16 of the initial the concentration
Calculate the halflife of a first order reaction from their rate constants given below:
200 s−1
2 min−1
4 yr−1
The experimental data for decomposition of N_{2}O_{5}
in gas phase at 318K are given below:

t(s)
0
400
800
1200
1600
2000
2400
2800
3200
1.63
1.36
1.14
0.93
0.78
0.64
0.53
0.43
0.35
(i) Plot [N_{2}O_{5}] against t.
(ii) Find the halflife period for the reaction.
(iii) Draw a graph between log [N_{2}O_{5}] and t.
(iv) What is the rate law?
(v) Calculate the rate constant.
(vi) Calculate the halflife period from k and compare it with (ii).
 3, 1
 1, 1
 0, 12
 2, 2
 20 hours
 10 hours
 7.5 hours
 5 hours
 1.25 g
 0.39 g
 1.77 g
 0.5 g
 10−2s−1
 10−4s−1
 10s−1
 102s−1
 zero
 first
 second
 164g
 116g
 18g
 132g
 23.1 min
 8.73 min
 0.383 min
 7.53 min
The rate of the chemical reaction doubles for an increase of 10 K in absolute temperature from 298 K. Calculate E_{a}.
 0.05M
 0.375M
 0.06M
 0.125M
(i) How is the rate of reaction affected if the concentration of B is doubled?
(ii) What is the overall order of reaction if A is present in large excess?
(b) A first order reaction takes 23.1 minutes for 50% completion. Calculate the time required for 75% completion of this reaction. (log 2 =0.301, log 3 =0.4771, log 4 =0.6021)
A(aq)+H2O→B(aq)+C(aq)
If concentration of A(aq) initially and after 6.93 minutes is 1 M & 14 M respectively then calculate rate constant in terms of M−1min−1.
(Given: log2=0.3010)
 15
 110
 3.6×10−3
 1.8×10−3
 Is tripled
 Is doubled
 Is halved
 Remains unchanged
 Half life period for a first order reaction depends directly on the concentration of the reactant(s).
 Time of completion for first order reaction is infinity
 Half life period for a first order reaction does not depend on the concentration of the reactant(s).
 Average Life for First Order Reaction (tav)=1k
For the decomposition reaction NH2COONH4(s)⇋ 2NH3(g) + CO2(g). The Kp= 2.9 × 10−5atm2. The partial pressure of CO2 at equilibrium when 2 mole of NH2COONH4(s) was taken to start with would be
2 atm
 Only experimental method
 Only theoretical method
 Both experimental and theoritical method
 None of the above
 three natural life time
 two natural life time
 one natural life time
 four natural life time
 Independent of the initial concentration of the reactant
 Directly proportional to the initial concentration of the reactant
 Inversely proportional to the initial concentration of the reactant
 Directly proportional to the square of the initial concentration of the reactant
What will be the effect of temperature on rate constant?
if [A]=0.5 M, then the value of −d[A]dt (in Ms−1) is :
7.5×10−5
3×10−4
2.5×10−5 1.25×10−6 Ms−1
 A firstorder reaction can be catalyzed; a secondorder reaction cannot be catalyzed
 The halflife of a firstorder reaction does not depend on [A]0; the halflife of a secondorder reaction depends on [A]0
 The rate of a firstorder reaction does not depend on reactant concentrations; the rate of a secondorder reaction depends on reactant concentrations
 The rate of a firstorder reaction depends on reactant concentrations; the rate of a secondorder reaction does not depend on reactant concentrations
 t75%=2t1/2
 t87.5%=3t1/2
 t99.9%=9t1/2
 t96.87%=4t1/2
 20 s
 50 s
 30 s
 15 s