Chemistry - Rates of Chemical Reactions and Chemical Kinetics
Exam Duration: 45 Mins Total Questions : 30
If the rate constant of a reaction is 2.0 mol-1 L-1 at 700 K and 32 mol-1 L s-1 at 800 K the activation energy for the reaction is
- (a)
120.11 kJ mol-1
- (b)
127.11 kJ mol-1
- (c)
129.11 kJ mol-1
- (d)
130.11 kJ mol-1
The rate of a particular reaction quadruples, when the temperature chages from 293 K to 313 K. The activation energy for such reaction would be
- (a)
50.855 kJ mol-1
- (b)
52.855 kJ mol-1
- (c)
54.855 kJ mol-1
- (d)
56.855 kJ mol-1
Which one of the following statements is wrong in case of enzyme catalysis?
- (a)
Enzymes work best at an optimum temperature
- (b)
Enzymes work at optimum pH value
- (c)
Enzymes are highly specific for substrates
- (d)
Enzyme raises activation energy
A reaction that is of first order with respect to reactant A has a rate constant 6 mim-1. If we start with [A] = 0.5 mol L-1, when would [A] reach the value 0.05 mol L-1?
- (a)
3.84 min
- (b)
3 min
- (c)
0.15 min
- (d)
0.384 min
For the reaction :
\({ CHCl }_{ 3 }(g)\quad +\quad { Cl }_{ 2 }(g)\quad \longrightarrow \quad { CCl }_{ 4 }(g)+HCl(g)\) the rate is given by the expression: k[CHCl3] [Cl2]1/2 The dimensions of the rate constant in this case would be
- (a)
s-1
- (b)
mol-1/2 L1/2 s-1
- (c)
L mol-1 s-1
- (d)
L2 mol-2 s-1
The activation energy for the reaction \(2HI(g)\quad \rightleftharpoons \quad { H }_{ 2 }(g)+{ I }_{ 2 }(g)\) is 209.5 kJ mol-1 at 581 K. The fraction of molecules of reactants having energy equal to or greater than activation energy would be
- (a)
1.462 x 1024
- (b)
1.462 X 10-19
- (c)
1.462 X 1028
- (d)
1.462 X 1034
Which is not true of first order reaction?
- (a)
Half-life time is independent of initial
- (b)
Unit for first order reation is sec-1
- (c)
log C vs Time plot is Straight line
- (d)
Rate increases with decrease in concentraction of reactants.
The half life period for catalytic decomposition of \(AB_3\) at 50 mm is found to be 4 hours and at 100 mm it is 2.0 hours. The order of reaction is
- (a)
1
- (b)
2
- (c)
3
- (d)
0
A chemical reaction involved two reacting species. The rate reaction is directly proportional to the concentraction of one of them and inversly proportional to the concentration of the other. The order of reaction is
- (a)
zero
- (b)
1
- (c)
2
- (d)
unpredictable
The rate of reaction can be measured by nothing the change in some property of the reaction. The rate of reaction of which one of the following reactions can be studied by nothing down the pH change?
- (a)
\({ N }_{ 2 }{ O }_{ 4 }(g)\rightarrow 2{ NO }_{ 2 }(g)\)
- (b)
\({ N }_{ 2 }{ O }_{ 4 }(g)\rightarrow 2{ NO }_{ 2 }(g)+1/2{ O }_{ 2 }(g)\)
- (c)
\({ C }_{ 12 }{ H }_{ 22 }{ O }_{ 11 }\rightarrow { C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+{ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }\\ sucrose\quad \quad \quad \quad glucose\quad \quad fructose\)
- (d)
\({ CH }_{ 3 }COO{ C }_{ 2 }{ H }_{ 5 }(aq)+{ H }_{ 2 }O(l)\rightarrow { CH }_{ 3 }COOH(aq)+{ C }_{ 2 }{ H }_{ 5 }OH(aq)\)
The rate expression for the reaction
aA \(\rightarrow\) Product, would be
- (a)
\(\frac { -d[A] }{ dt } =k{ [A] }^{ a }\)
- (b)
\(\frac { -d[A] }{ dt } =k{ [A] }^{ 0 }\)
- (c)
\(\frac { -d[A] }{ dt } =k{ [A] }^{ x }\)
- (d)
\(\frac { -d[A] }{ dt } =k{ [A] }^{ 1 }\)
For a reaction of type A + B \(\rightarrow \) Products, it is observed that doubling concentration of A causes the reaction rate to be four times as great, but doubling amount of B does not affect the rate. The rate equation is
- (a)
rate = k [A] [B]
- (b)
\(rate\quad =\quad \frac { k }{ 4 } [A]^{ 2 }\)
- (c)
rate = k [A]2 [B]0
- (d)
rate = k [A]2 [B]2
The rate of a gaseous reaction is given by the expression k [A] [B]. If the volume of the reaction vessel is suddenly reduced to \(\frac { 1 }{ 4 } \)th of the original volume, the reaction rate relating to the original rate would be
- (a)
\(\frac { 1 }{ 10 } \)
- (b)
\(\frac { 1 }{ 8 } \)
- (c)
8
- (d)
16
A reaction \(A\rightarrow B\) follows a second order kinetics. Doubling the concentration of A will increase the rate of formation of B by a factor of
- (a)
2
- (b)
1/2
- (c)
4
- (d)
1/4
In a catalytic conversion of N2 to NH3 by Haber's process, the rate of reaction expressed as change in the concentration of ammonia per times is 40 X 10-13 mol-1s-1. If there are no side reactions, the rate of the reaction as expressed in terms of hydrogen is
- (a)
60 X 10-3 mol-1 s-1
- (b)
20 X 10-3 mol-1 s-1
- (c)
30 X 10-3 mol-1 s-1
- (d)
10 X 10-3 mol-1 s-1
For the chemical reaction
A + 2B \(\rightarrow\) Product
the rate of teh reaction is given by
- (a)
\(\frac { 1 }{ 2 } \frac { d[A] }{ dt } \)
- (b)
\( \frac { d[B] }{ dt } \)
- (c)
\(\frac { d[A] }{ dt } =\frac { d[B] }{ dt } \)
- (d)
\(\frac { d[A] }{ dt } =\frac { 1 }{ 2 } \frac { d[B] }{ dt } \)
Diazonium salt dicomposes as
\({ C }_{ 6 }{ H }_{ 3 }{ { N }_{ 2 } }^{ + }C{ l }^{ - }\rightarrow { C }_{ 6 }{ H }_{ 5 }Cl+{ N }_{ 2 }\)
At 00C, the evolution of N2 becomes two times faster when initial concentration of the salt is doubled. Thus it is
- (a)
a first order reaction
- (b)
a second order reaction
- (c)
independent of initial concentration of reactants
- (d)
a zero order reaction
The differential rate law for reaction:
\({ H }_{ 2 }+{ I }_{ 2 }\rightarrow 2HI\) is
- (a)
\(-\frac { d[{ H }_{ 2 }] }{ dt } =-\frac { d[{ I }_{ 2 }] }{ dt } =-\frac { d[HI] }{ dt } \)
- (b)
\(\frac { d[{ H }_{ 2 }] }{ dt } =\frac { d[HI] }{ dt } =\frac { 1 }{ 2 } \frac { d[HI] }{ dt } \)
- (c)
\(\frac { 1 }{ 2 } \frac { d[{ H }_{ 2 }] }{ dt } =\frac { 1 }{ 2 } .\frac { d[{ I }_{ 2 }] }{ dt } =-\frac { d[HI] }{ dt } \)
- (d)
\(-\frac { 2d[HI] }{ dt } =\frac { -2d[{ I }_{ 2 }] }{ dt } =\frac { d[HI] }{ dt } \)
In the following reaction, if Y is taken in larger amounts, the order of the reaction is X+Y\(\longrightarrow\) P
- (a)
zero order reaction
- (b)
first order reaction
- (c)
second order reaction
- (d)
pseudo unimolecular reaction
Activation energy of a chemical reaction can be determined by
- (a)
determining the rate constant at standard temperature
- (b)
determining the rate constant at two temperature
- (c)
determining probability of collision
- (d)
using catalyst
Consider the following reaction, \(2N_2O_5\longrightarrow4NO_2+O_2+{d[NO_2]\over dt}=k_2[N_2O_5]\)\({d[O_2]\over dt}=k_3[N_2O_5],{d\over dE}[N_2O_5]=k_1\)The relation between k1,k2 and k3 is
- (a)
k1=k2=k3
- (b)
2k1=k2=4k3
- (c)
2k1=4k2=k3
- (d)
None of these
Consider the following reaction, \(2A+B+C\longrightarrow\) products How will the rate of reaction changes when the concentration of A is doubled and that B is tripled while C is taken in excess?
- (a)
The rate reduces 8 times of its original value
- (b)
The rate reduces 12 times of its original value
- (c)
The rate of increase 8 times of its original value
- (d)
The rate of increases 12 times of its original value
In the reaction, \(xA+yB\longrightarrow\)Products.If the concentration of both the reactants, A and B is doubled, the rate increases by eight times.But when the concentration of A is doubled keeping the concentration of B constant the rate of reaction is doubled.The order of the reaction is
- (a)
3
- (b)
2
- (c)
1
- (d)
0
The rate constant for the first order reaction is 60s-1.How much time will it take to reduce the concentration of the reactant to 1/16th value?
- (a)
4.6x104s
- (b)
4.6x10-4s
- (c)
4.6x10-2s
- (d)
4.6x102s
The rate of a reaction double when its temperature changes from 300k to reaction will be9R=3.314JK-1 mol-1 and log2=0.301)
- (a)
53.6KJ mol-1
- (b)
48.6KJ mol-1
- (c)
58.5KJ mol-1
- (d)
60.5KJ mol-1
The rate of a chemical reaction double for every 100C rise of temperature.If the temperature is raised by 50 0, the rate of reaction increase by about
- (a)
10times
- (b)
24 times
- (c)
32 times
- (d)
64 times
The half-life period of a first order chemical reaction is 6.93min.The time required for the completion of 99% of chemical reaction will be
- (a)
230.6 min
- (b)
23.03 min
- (c)
46.06 min
- (d)
460.6 min
For a reaction, \({1\over2}A\longrightarrow2B,\) rate of disappearance of 'A' is related of the rate of appearance of 'B' by the expression
- (a)
\(-{d[A]\over dt}={1\over2}{d[B]\over dt}\)
- (b)
\(-{d[A]\over dt}={1\over4}{d[B]\over dt}\)
- (c)
\(-{d[A]\over dt}={d[B]\over dt}\)
- (d)
\(-{d[A]\over dt}=4{d[B]\over dt}\)
A radioactive element gets spilled over the floor of a room.Its half-life period is 30 days.If the initial activity is ten times the permissible value, after how many days will it be safe to enter the room?
- (a)
1000 days
- (b)
300 days
- (c)
10 days
- (d)
100 days
A reaction involving two different reactants can never be
- (a)
bimolecular reaction
- (b)
second order reaction
- (c)
first order reaction
- (d)
unimolecular reaction