The chemical reaction, 2O3 →3O2 proceeds as follows;
O3 ⇌O2 + O .....(Fast)
O+O3 → 2O2 ....(Slow)
The rate law expression should be:
r = K[O3]2
r = K[O3]2[O2]-1
r = K[O3][O2]
unpredictable
The rate of reaction becomes 2 times for every 10°C rise in temperature. How the rate of reaction will increase when temperature is increased from 30°C to 80°C?
16
32
64
128
The rate constant (K) for the reaction 2A +B → Product was found to be 2.5x10-5 litre mol-1 sec-1 after 15 sec, 2.60 x10-5 litre mol-1sec-1 after 30 sec and 2.55 x10-5litre mol-1 sec-1 after 50 sec. The order of reaction is:
2
3
zero
1
A reaction A2 + B2 → 2AB occurs by the following mechanism;
A2 → A + A .....(slow)
A + B2 → AB + B .....(fast)
A + B → AB .....(fast)
Its order would be:
3/2
0
For a given reaction, presence of catalyst reduces the energy of activation by 2 kcal at 27°C. The rate of reaction will be increased by:
20 times
14 times
28 times
2 times
What fraction of a reactant showing first order remains after 40 minute if t1/2 is 20 minute?
1/4
1/2
1/8
1/6
Rate equation for a second order reaction is:
K = (2.303/t) log {a/(a-x)}
K = (1/t) log {a/(a-x)}
K = (1(a)t-1(ao)t)* 1t
K = (1/t2) log {a/(a-x)}
If 2M, 1L solution of acetic acid is added to 3M, 1L ethyl alcohol then the following elementary reaction takes place.
CH3COOH + C2H5OH → CH3COOC2H5 + H20
If each solution is diluted by 1 litre then the initial rate becomes how many times:-
4
0.5
0.25
For the reaction 2NO2 + F2 → 2NO2F, following
mechanism has been provided,
NO2 + F2 →slow NO2F+F
NO2 + F →fast NO2F
Thus, rate expression of the above
reaction can be written as:
r = K[NO2]2[F2]
r = K[NO2 ][F2]
r = K[NO2]
r = K[F2]
For the reaction:
[Cu(NH3)4]2+ + H2O⇌[Cu(NH3)3H2O]2+ + NH3
the net rate of reaction at any time is given by, net rate =
2.0x10-4 [Cu(NH3)4]2+[H2O] - 3.0x105 [Cu(NH3 )3 H20]2+[NH3]
Then correct statement is/are :
rate constant for forward reaction = 2 x 10-4
rate constant for backward reaction = 3 x 105
equilibrium constant for the reaction = 6.6 x 10-10
all of the above
Rate constant of reaction can be expressed by Arrhenius equation as,
K=Ae-EaRT
In this equation, Ea represents:
the energy above which all the colliding molecules will react
the energy below which colliding molecules will not react
the total energy of the reacting molecules at a temperature, T
the fraction of molecules with energy greater than the activation energy of the reaction
Consider the chemical reaction,
N2g+3H2g→2NH3g
The rate of this reaction can be expressed in terms of time derivative of concentration of N2 g, H2g and NH3g.
The correct relationship amongest the rate expressions is:
Rate =-dN2dt=-13 dH2dt=12 dNH3dt
Rate =-dN2dt=-3 dH2dt=2 dNH3dt
Rate =dN2dt=13 dH2dt=12 dNH3dt
Rate =-dN2dt=- dH2dt= dNH3dt
For a first order reaction A→ Product, the initial concentration of A is 0.1 M and after 40 minute it becomes 0.025 M. Calculate the rate of reaction at reactant concentration of 0.01M:
3.47x10-4 M min-1
3.47x10-5 M min-1
1.735 x 10-6 M min-1
1.735 x10-4 M min-1
Select the intermediate in the following reaction mechanism:
O3(g) ⇌ O2(g) +O(g)
O(g) +O3(g) → 2O2(g)
O3(g)
O(g)
O2(g)
none of these
A reactant with initial concentration 1.386 mol litre-1 showing first order change takes 40 minute to become half. If it shows zero order change taking 20 minute to becomes half under the similar conditions, the ratio, K1/K0 for first order and zero order kinetics will be:
0.5 mol-1 litre
1.0 mol/litre
1.5 mol/litre
2.0 mol-1 litre
In a first order reaction, the concentration of the reactant is decreased from 1.0 M to 0.25M in 20 minute. The rate constant of the reaction would be:
10min-1
6.931 min-1
0.6931 min-1
0.06931 min-1
The following mechanism has been proposed for the reaction of NO with Br2 to form NOBr:
NO(g) + Br2(g) ⇌ NOBr2(g)
NOBr2(g) + NO(g) →2NOBr(g)
If the second step is the rate determining step, the order of the reaction with respect to NO(g) is:
For the reaction A → nB, at the point of intersection of two curves show, the [B] is can be given by:
nA02
A0n-1
nA0n+1
n-1n+1A0
The rate constant of a first order reaction is 4x10-3 sec-1. At a reactant concentration of 0.02 M, the rate of reaction would be:
8 x 10-5 M sec-1
4 x 10-3 M sec-1
2 x 10-1 M sec-1
4 x 10-1 M sec-1
If concentration of reactants is increased by 'X', the rate constant K becomes:
eK/X
K/X
K
X/K
In acidic medium the rate of reaction between (BrO3)- and Br- ions is given by the expression
-d(BrO3-)dt=KBrO3-Br-H+2
It means:
Rate constant of overall reaction is 4 sec-1
Rate of reaction is independant of the concentration of acid
The change in pH of the solution will not affect the rate
Doubling the conc. of H+ ions will increase the reaction rate by 4 times
A graph plotted between log (t) 50% vs. log (a) concentration is a straight line. What conclusion can you draw from the given graph?
n=1, t1/2 = 1/K.a
n=2, t1/2 = 1/a
n=1, t1/2 = 0.693/K
None of the above
For a first-order reaction A→ Products, the rate of reaction at [A] = 0.2 M is 1.0 x 10-2 mol litre-1 min-1. The half-life period for the reaction is-
832 sec
440 sec
416 sec
14 sec
The rate of a chemical reaction doubles for every 10°C rise of temperature. If the temperature is raised by 50°C, the rate of the reaction increases by about :
10 times
24 times
32 times
64 times
Consider the reaction:
Cl2(aq) + H2S(aq) → S(s) +2H+(aq) +2Cl-(aq)
The rate equation for this reaction is rate = k[Cl2][H2S] Which of these mechanisms is/are consistent with this rate equation?
A. Cl2 + H2S → H+ + Cl- +Cl+ + HS- (slow)
cl+ + HS- → H+ +Cl- + S (fast)
B. H2S ⇔ H+ + HS- (fast equilibrium)
Cl2 + HS- → 2Cl- + H+ + S (slow)
A only
B only
Both A and B
Neither A nor B
3A → C + D, For this reaction it is observed that when initial concentration of A is 10 mole/lit then t1/2 value of this reaction is 40 min and when initial concentration of A is 20 mole / lit, t1/2 value has been changed into 20 min. Which of the following is true?
The reaction is bimolecular reaction
This reaction is an example of radioactive disintegration
The reaction is of 1st order
The order of the reaction is two
In the following reaction : xA → yB
log-d[A]dt= log d[B]dt + 0.3
where -ve sign indicates the rate of disappearance of the reactant. Then x : y is -
1:2
2:1
3:1
3:10
Half-life is independent of the concentration of reactant. After 10 minutes volume of N2 gas is 10L and after complete reaction, it is 50 L. Hence rate constant is :
2.30310log 5 min-1
2.30310 log 1.25 min-1
2.30310 log 2 min-1
2.30310 log 4 min-1
The activation energies of the forward and backward reactions in the case of a chemical reaction are 30.5 and 45.4 KJ/mol respectively. The reaction is
Exothermic
Endothermic
Neither exothermic nor endothermic
Independent of temperature
The t0.5 for the first order reaction.
PCl5(g) →PCl3(g) + Cl2(g) is 20 min. The time in which the conc. of PCl5 reduces to 25% of the initial conc. is close to
22 min
40 min
90 min
50 min
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