JEE Main Chemistry - Rates of Chemical Reactions and Chemical Kinetics
Exam Duration: 60 Mins Total Questions : 30
For a first order reaction k=5.48 x10-4s-1. The two-third life for this reaction wound be
- (a)
2005 s
- (b)
1000 s
- (c)
2000 s
- (d)
3005 s
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
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 following reaction, which one you think will go with moderate rate
- (a)
\({ Cr }^{ 2+ }{ (aq) }{ + }{ Fe }^{ 3+ }(aq){ \longrightarrow }{ Cr }^{ 3+ }(aq)+{ Fe }^{ 2+ }(aq)\)
- (b)
\({ 2NO }_{ 2 }{ \longrightarrow }{ N }_{ 2 }{ O }_{ 4 }\)
- (c)
\({ 3Fe }^{ 2+ }(aq)+{ NO }_{ 3 }(aq)+{ 4H }^{ + }(aq)\longrightarrow 3{ Fe }^{ 3+ }(aq)+NO(g)+{ 2H }_{ 2 }O\)
- (d)
\({ C }_{ 8 }{ H }_{ 18 }+{ 12 }_{ 1/2 }{ O }_{ 2 }\longrightarrow { 8CO }_{ 2 }(g)+{ 9H }_{ 2 }O(g)\)
For the reaction: \({ 2N }_{ 2 }{ O }_{ 5 }\longrightarrow { 4NO }_{ 2 }+{ O }_{ 2 }\), the rate of reaction can be expressed in three ways, e.g.,
\(-\frac { d\left[ { N }_{ 2 }{ O }_{ 5 } \right] }{ dt } =k\left[ { N }_{ 2 }{ o }_{ 5 } \right] \)
\(+\frac { d\left[ { NO }_{ 2 } \right] }{ dt } ={ k }^{ 1 }\left[ { N }_{ 2 }{ o }_{ 5 } \right] \)
\(+\frac { d\left[ { O }_{ 2 } \right] }{ dt } ={ k }^{ 11 }\left[ { N }_{ 2 }{ o }_{ 5 } \right] \)
The relation between k1 and k is
- (a)
k1=2k
- (b)
k1=1/2k
- (c)
k1=\(\frac { 3 }{ 2 } k\)
- (d)
\(\frac { 5 }{ 2 } k\)
For the reaction: 2NO(g)+O2 \(\rightleftharpoons \) 2NO(g), if the volume of the reaction vessel is diminished to \(\frac { 1 }{ 3 } \) of its volume, the rate of the reaction will change to
- (a)
4 times
- (b)
3 times
- (c)
2 times
- (d)
half times
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 one of the following has an overall order of \(\frac { 3 }{ 2 } \)?
- (a)
\({ H }_{ 2 }+{ I }_{ 2 }\longrightarrow 2HI\)
- (b)
\({ H }_{ 2 }+{ Br }_{ 2 }\longrightarrow 2HBr\)
- (c)
\({ 2O }_{ 3 }\longrightarrow { 3O }_{ 2 }\)
- (d)
NONE OF THE ABOVE
The activation energy of reaction I is 80 kJ mol-1 and that of reaction II is 60 kJ mol-1. which of the following statements is correct?
- (a)
The rate of reaction II is greater than that of I
- (b)
The rate constant of reaction II is greater than that of I
- (c)
The order of reaction I is greater than that of II
- (d)
The molecularity of reaction II is less than that of I.
The reaction : A + 2B \(\rightarrow\) C+D obeys the rate equation. Rate = K [A]x [B]y
The overall order of this reaction is
- (a)
x
- (b)
y
- (c)
(x + y)
- (d)
zero
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 the reaction A \(\rightarrow \) B, the rate law expression is rate = k[A]. Which of the following statements is incorrect?
- (a)
The reaction follows first order kinetics
- (b)
The t1/2 of reaction depends on initial concentration of reactants
- (c)
K is constant for the reaction at a constant temperature
- (d)
The rate law provides a simply way of predicting the concentration of the reactants and products at any time after the start of the reaction
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
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
A substance 'A' decomposes in solution following the first order Kinetics. Flask I contains 1 L of 1 M solution of A and flask II contains 100ml of 0.6 M solution. After 8 hour the concentration of A in flsk I becomes 0.25. What will be the time for concentration of A in flask II to become 0.3 M?
- (a)
0.4 hr
- (b)
2.4 hr
- (c)
4.0 hr
- (d)
unpredictable as the rate concentration is not given.
The reaction \(2{ N }_{ 2 }{ O }_{ 5 }(g)\rightarrow 4N{ O }_{ 2 }(g)+{ O }_{ 2 }(g)\) is first order w.r.t. N2O5. Which of the following graphs would yield a straight line?
- (a)
Log p N2O5 vs. time with a -ve slope
- (b)
(p N2O5)-1 vs. time
- (c)
p N2O5 vs. time
- (d)
log p N2O5 vs time with a +ve slope.
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)
\(-\frac { 2d[HI] }{ dt } =\frac { -2d[{ I }_{ 2 }] }{ dt } =\frac { d[HI] }{ dt } \)
Consider the following reaction,\(2OP_2O_5(s)\longrightarrow4PO_2(g)+O_2(g)\) if the concentration of PO2 increases by 5.2x10-3M in 100S, the rate of a reaction is
- (a)
0.5x10-4Ms-1
- (b)
2.5x10-5Ms-1
- (c)
1.3x10-5Ms-1
- (d)
2x103Ms-1
The correct statement is
- (a)
increases in the concentration of reactant (s) causes a decrease in the rate of a reaction
- (b)
the rate of a reaction becomes constant at any time during the reaction
- (c)
the rate of reaction does not changes with a change in time
- (d)
the rate of a reaction decreases with decrease in concentration of reactant
Consider the following reaction, \(N_2(g)+3H_2(g)\rightleftharpoons 2NH_3(g)\)The rate of change of concentration of ammonia is
- (a)
0.2x10-4Ms-1
- (b)
0.4x10-4Ms-1
- (c)
0.6x10-4Ms-1
- (d)
-0.6x10-4Ms-1
For the reaction, R\(\longrightarrow\)P, the concentration of a reactant changes from 0.03M to 0.02M in 25 min.Calculate the average rate of reaction using units of time in seconds.
- (a)
6.66x10-5
- (b)
6.6x10-6
- (c)
5.67x10-5
- (d)
7.26x10-6
Powered magnesium element catches fire more rapidly than magnesium wire of the same mass because
- (a)
surface area of magnesium wire is larger than their powered form
- (b)
density of magnesium wire is greater than of their powered form
- (c)
powered magnesium have larger surface area
- (d)
None of the above
Compounds 'A' and 'B' react according to the following chemical equation, \(A(g)+2B(g)\longrightarrow2C(g)\)Concentration of either 'A' or 'B' were changed keeping the concentrations of one of the reactants constant and rates were measured as a function of initial concentration.Following results were obtained.Choose the correct option for this reaction.
Experiment | Initial com. of [A]/mol L-1 | Initial com. of [A]/mol L-1 | Initial rate of formation of [CV]/mol L-1s-1 |
1. | 0.30 | 0.30 | 0.10 |
2. | 0.30 | 0.60 | 0.40 |
3. | 0.60 | 0.30 | 0.20 |
- (a)
Rate=k[A]2[B]
- (b)
Rate=k[A][B]2
- (c)
Rate=k[A][B]
- (d)
Rate=k[A]2[B]0
For a unimolecular reaction
- (a)
the molecularity and order of a reaction is one
- (b)
the molecularity of the reaction is one while their order is zero
- (c)
two reacting species are involved in the rate determining
- (d)
the molecularity and order of the slowest step of the reaction is equal to one
Which one of the following expressions is incorrect for the first order reaction?
- (a)
\(Rate=k[A]\)
- (b)
\(k={t\over2.303}log\left( A_0\over A_t \right) \)
- (c)
\(k={2.303\over t}log\left( A_0\over A_t \right) \)
- (d)
\(-k={t\over2.303}log\left( A_0\over A_t \right) \)
For a complex reaction
- (a)
order of the overall reaction is larger than the molecularity of the slowest step
- (b)
order of the overall reaction is smaller than the molecularity of the slowest step
- (c)
order of the overall reaction is same as the molecularity of the slowest step is zero
- (d)
molecularity of the slowest step is zero
Consider the following reaction, \(5Br^-(aq)+BrO^{-}_{3}(aq)+6H^+(aq)\longrightarrow3Br_2(aq)+3H_2O(l)\) Which one of the following expression is correct for the rate of reaction for the above chemical equation?
- (a)
\({\Delta[Br^-]\over\Delta t}=6{\Delta[H^+]\over\Delta t}\)
- (b)
\({\Delta[Br^-]\over\Delta t}={6\over5}{\Delta[H^+]\over\Delta t}\)
- (c)
\({\Delta[Br^-]\over\Delta t}=5{\Delta[H^+]\over\Delta t}\)
- (d)
\({\Delta[Br^-]\over\Delta t}={5\over6}{\Delta[H^+]\over\Delta t}\)
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
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)
\(-{d[A]\over dt}=4{d[B]\over dt}\)
The following mechanism has been proposed for the reaction of NO with Br2 to form NOBr
\(NO(g)+Br_2(g)\rightleftharpoons NOBr_2(g)\)
\(NOBr_2(g)+NO(g)\longrightarrow 2NOBr(g)\)
If the second step is the rate determining step, the order of the reaction with respect to NO(g) is
- (a)
1
- (b)
0
- (c)
3
- (d)
2