Chemical Kinetics

Given below are two statements : R = 8.314 J K-1 mol-1 and 1 cal = 4.2 J In the light of the above statements, choose the correct answer from the options given below :

1. Both Statement I and Statement II are true
2. Both Statement I and Statement II are false
3. Statement I is true but Statement II is false
4. Statement I is false but Statement II is true

Sucrose hydrolyses in acidic medium into glucose and fructose by first order rate law with t1/2 = 3 hour. The percentage of sucrose remaining after 6 hours is . (Nearest integer) (Given : log 2 = 0.3010 and log 3 = 0.4771)

Decomposition of a hydrocarbon follows the equation k = (5.5 1011 s-1) e-28000 K/T. The activation energy of reaction is kJ mol-1. (Nearest Integer) Given : R = 8.3 J K-1 mol-1

First order gas phase reaction A B + C pi = initial pressure of gas A, pt = total pressure of the reaction mixture at time t Expression of rate constant (k) is

1. 1t pi2pi - pt
2. 1t 2pipi - pt
3. 1t pi3pi - 2pt
4. 1t 3pi4pi - pt

If the half life of a first order reaction is 6.93 minutes then the time required for completion of 99% of the reaction will be minutes. (Given : log 2 = 0.3010)

For a reaction A → P at T K, the half life (t1/2) is plotted as a function of initial concentration [A]0 of A as given below. [figure] The value of x in the given figure is s (Nearest integer)

Consider the first order reaction R P. The fraction of molecules decomposed in the given first order reaction can be expressed as

1. 1 - ek1t
2. 1 + ek1t
3. 1 + e-k1t
4. 1 - e-k1t

Consider the given graph showing variation of reactant concentration with time. Three different reactions were started with identical initial concentration of reactants. Which of the following statement is correct? [figure]

1. The order of all the three reactions is same.
2. The rate constant of reaction 3 is larger than the rate constant of reaction 2 if the order of reaction is same for both.
3. The SI unit of rate constant of reaction 1 is s-1.
4. Thermal decomposition of HI on gold surface is an example of reaction 2.

For a first order reaction A B arrayll t/min & [A]/M \ 0 & 0.6500 \ x & 0.0650 \ 20 & 0.00065 array x = min. (Nearest integer)

t100\% is the time required for the 100% completion of the reaction while t1/2 is the time required for 50% of the reaction to be completed. Which of the following option correctly represents the relation between t100\% and t1/2 for zero and first order reactions respectively ?

1. t100\% = (t1/2)2 and t100\% = (t1/2)-
2. t100\% = 2t1/2 and t100\% = (t1/2)
3. t100\% = 2t1/2 and t100\% = (2t1/2)2
4. t100\% = (t1/2) and t100\% = 2t1/2

For reaction A P, rate constant k = 1.5 103 s-1 at 27°C If activation energy for the above reaction is 60 kJ mol-1, then the temperature (in °C) at which rate constant, k = 4.5 103 s-1 is . (Nearest integer) Given : log 2 = 0.30, log 3 = 0.48, R = 8.3 J K-1 mol-1, ln 10 = 2.3

Consider the reaction aX bY, for which the rate constant at 30°C is 1 10-3 mol-1 L s-1. Which of the following statements are true? Choose the correct answer from the options given below:

1. A and B Only
2. A, B and C Only
3. A, B, D and E Only
4. C and D Only

Consider the following gas phase reaction being carried out in a closed vessel at 25°C. 2A(g) 4B(g) + C(g) array|c|c| time (min) & total pressure of the system (mm Hg) \ 30 & 300 \ & 600 \ array The pressure of C(g) at 30 minutes time interval would be mm Hg. (nearest integer)

An organic compound undergoes first order decomposition. The time taken for decomposition to ( 18 )th and ( 110 )th of its initial concentration are t1/8 and t1/10 respectively. What is the value of t1/8 t1/10 10? ( 2 = 0.3)

1. 30
2. 9
3. 3
4. 0.9

A → B (first reaction) C → D (second reaction) Consider the above two first-order reactions. The rate constant for first reaction at 500 K is double of the same at 300 K. At 500 K, 50% of the reaction becomes complete in 2 hours. The activation energy of the second reaction is half of that of first reaction. If the rate constant at 500 K of the second reaction becomes double of the rate constant of first reaction at the same temperature; then rate constant for the second reaction at 300 K is 10-1 hour-1 (nearest integer).

A D is an endothermic reaction occurring in three steps (elementary). (i) A B, Hi = +ve (ii) B C, Hii = -ve (iii) C D, Hiii = -ve Which of the following graphs between potential energy (y-axis) vs reaction coordinate (x-axis) correctly represents the reaction profile of A D?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

At 27 in presence of a catalyst, activation energy of a reaction is lowered by 10 kJ mol-1. The logarithm of ratio of k (catalysed)k (uncatalysed) is.... (Consider that the frequency factor for both the reactions is same)

1. 1.741
2. 0.1741
3. 17.41
4. 3.482

The half-life of 65Zn is 245 days. After x days, 75\% of original activity remained. The value of x in days is . (Nearest integer) (Given: 3 = 0.4771 and 2 = 0.3010)

For the thermal decomposition of reactant AB(g), the following plot is constructed. [figure] The half-life of the reaction is 'x' min. x = min. (Nearest integer)

[figure] Given above is the concentration vs time plot for a dissociation reaction : A nB. Based on the data of the initial phase of the reaction (initial 10 min), the value of n is .

1. 2
2. 5
3. 4
4. 3

Observe the following reactions at T(K). I. A products. II. 5Br-(aq) + BrO3-(aq) + 6H+(aq) 3Br2(aq) + 3H2O(l) Both the reactions are started at 10.00 am. The rates of these reactions at 10.10 am are same. The value of - [Br-] t at 10.10 am is 2 10-4 mol L-1 min-1. The concentration of A at 10.10 am is 10-2 mol L-1. What is the first order rate constant (in min-1) of reaction I?

1. 4 10-3
2. 2 10-3
3. 10-3
4. 10-2

A product (First order reaction). Three sets of experiments were performed for a reaction under similar experimental conditions: Run 1 100 mL of 10 M solution of reactant A Run 2 200 mL of 10 M solution of reactant A Run 3 100 mL of 10 M solution of reactant A + 100 mL of H2O added. The correct variation of rate of reaction is

1. Run 1 = Run 2 = Run 3
2. Run 3 < Run 1 < Run 2
3. Run 1 < Run 2 < Run 3
4. Run 3 < Run 1 = Run 2

The temperature at which the rate constants of the given below two gaseous reactions become equal is K. (Nearest integer) X Y, k1 = 106 e -30000T P Q, k2 = 104 e -24000T Given : 10 = 2.303

Correct statements regarding Arrhenius equation among the following are : Choose the correct answer from the options given below :

1. A and B Only
2. B and D Only
3. B and C Only
4. A and C Only

Consider A k1 B and C k2 D are two reactions. If the rate constant (k1) of the A B reaction can be expressed by the following equation 10 k = 14.34 - 1.5 104T/K and activation energy of C D reaction (Ea2) is 15th of the A B reaction (Ea1), then the value of (Ea2) is kJ mol-1. (Nearest Integer)

Pre-exponential factors of two different reactions of same order are identical. Let activation energy of first reaction exceed the activation energy of second reaction by 20 kJ mol-1. If k1 and k2 are the rate constants of first and second reaction respectively at 300 K, then k2k1 will be . (nearest integer) [R = 8.3 J K-1 mol-1]

Decomposition of A is a first order reaction at T(K) and is given by A(g) B(g) + C(g). In a closed 1 L vessel, 1 bar A(g) is allowed to decompose at T(K). After 100 minutes, the total pressure was 1.5 bar. What is the rate constant (in min-1) of the reaction? ( 2 = 0.3)

1. 6.9 10-4
2. 6.9 10-3
3. 6.9 10-1
4. 6.9 10-2

In a first order decomposition reaction, the time taken for the decomposition of reactant to one fourth and one eighth of its initial concentration are t1 and t2 (s), respectively. The ratio t1/t2 will be:

1. 43
2. 32
3. 34
4. 23

A person's wound was exposed to some bacteria and then bacterial growth started to happen at the same place. The wound was later treated with some antibacterial medicine and the rate of bacterial decay (r) was found to be proportional with the square of the existing number of bacteria at any instance. Which of the following set of graphs correctly represents the 'before' and 'after' situation of the application of the medicine? [Given: N = No. of bacteria, t = time, bacterial growth follows 1st order kinetics.]

1. [figure]
2. [figure]
3. [figure]
4. [figure]

Reaction A(g) 2B(g) + C(g) is a first order reaction. It was started with pure A. array|c|c| t/min & Pressure of system at time t/mm Hg \ 10 & 160 \ & 240 \ array Which of the following option is incorrect?

1. Initial pressure of A is 80 mm Hg
2. The reaction never goes to completion
3. Partial pressure of A after 10 minutes is 40 mm Hg
4. Rate constant of the reaction is 1.693 min-1