If concentration of reactants is increased by 'X', the rate constant K becomes:
(a) eK/X
(b) K/X
(c) K
(d) X/K
A graph plotted between log (t) 50% vs. log (a) concentration is a straight line. What conclusion can you draw from the given graph?
(a) n=1, t1/2 = 1/K.a
(b) n=2, t1/2 = 1/a
(c) n=1, t1/2 = 0.693/K
(d) None of the above
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 :
(a) 10 times
(b) 24 times
(c) 32 times
(d) 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)
(1) A only
(2) B only
(3) Both A and B
(4) Neither A nor B
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
1. Exothermic
2. Endothermic
3. Neither exothermic nor endothermic
4. 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
1. 22 min
2. 40 min
3. 90 min
4. 50 min
For a certain reaction, 10% of the reactant dissociates in 1 hour, 20% of the reactant dissociate in 2 hour, 30% of the reactant dissociates in 3 hour. Then the units of the rate constant is:-
(1) hour-1
(2) mol L-1 hr-1
(3) L mol L-1 sec-1
(4) mol L sec-1
The activation energy of a reaction is zero. The rate constant of the reaction is :
(1) Increases with increase in temperature
(2) Decreases with decrease in temperature
(3) Decreases with increase in temperature
(4) Is nearly independent of temperature
For the pseudo first order reaction A + B P, when studied with 0.1 M of B is given by -d[A]/dt =k[A] where K = 1.85 x 104 sec-1. Calculate the value of rate constant for second order reaction :
(1) 1.85 x 104
(2) 1.85 x 10-4
(3) 1.85 x 10-5
(4) 1.85 x 105
When initial concentration of a reactant is doubled in a reaction, its half-life period is not affected. The order of the reaction is
(1) zero
(2) first
(3) second
(4) more than zero but less than first