Chemical Kinetics

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)

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

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)

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

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

A(g) B(g) + C(g) is a first order reaction. array|l|c|c| Time & t & \ Psystem & Pt & P \ array The reaction was started with reactant A only. Which of the following expressions is correct for rate constant k?

1. k = 1t P Pt
2. k = 1t P 2(P - Pt)
3. k = 1t 2(P - Pt)Pt
4. k = 1t P (P - Pt)

For bacterial growth in a cell culture, growth law is very similar to the law of radioactive decay. Which of the following graphs is most suitable to represent bacterial colony growth? Where N - Number of bacteria at any time, N0 - Initial number of bacteria.

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

For a reaction, N2O5(g) 2NO2(g) + 12O2(g) in a constant volume container, no products were present initially. The final pressure of the system when 50\% of reaction gets completed is

1. 5/2 times of initial pressure
2. 7/2 times of initial pressure
3. 7/4 times of initial pressure
4. 5 times of initial pressure

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

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

For the thermal decomposition of N2O5(g) at constant volume, the following table can be formed, for the reaction mentioned below. 2N2O5(g) 2N2O4(g)+O2(g) [figure] x= 10-3 atm [nearest integer] Given : Rate constant for the reaction is 4.606 10-2 s-1.

Consider the following first order gas phase reaction at constant temperature A(g) 2B(g) + C(g) If the total pressure of the gases is found to be 200 torr after 23 sec. and 300 torr upon the complete decomposition of A after a very long time, then the rate constant of the given reaction is 10-2 s-1 (nearest integer) [Given : 10(2) = 0.301]

Time required for 99.9\% completion of a first order reaction is times the time required for completion of 90\% reaction.(nearest integer)

Consider the two different first order reactions given below A + B C (Reaction 1) P Q (Reaction 2) The ratio of the half life of Reaction 1 : Reaction 2 is 5 : 2. If t1 and t2 represent the time taken to complete 2/3rd and 4/5th of Reaction 1 and Reaction 2, respectively, then the value of the ratio t1 : t2 is 10-1 (nearest integer). [Given : 10(3) = 0.477 and 10(5) = 0.699]

Consider the following reaction, the rate expression of which is given below A + B C rate = k[A]1/2[B]1/2 The reaction is initiated by taking 1 M concentration of A and B each. If the rate constant (k) is 4.6 10-2 s-1, then the time taken for A to become 0.1 M is sec. (nearest integer)

The following data were obtained during the first order thermal decomposition of a gas A at constant volume : A(g) 2B(g) + C(g) [figure] The rate constant of the reaction is 10-2 s-1 (nearest integer)

Integrated rate law equation for a first order gas phase reaction is given by (where Pi is initial pressure and Pt is total pressure at time t)

1. k = 2.303t Pi(2Pi - Pt)
2. k = 2.303t (2Pi - Pt)Pi
3. k = 2.303t Pi(2Pi - Pt)
4. k = 2.303t 2Pi(2Pi - Pt)

r = k[A] for a reaction, 50% of A is decomposed in 120 minutes. The time taken for 90% decomposition of A is minutes.

The rate of a first order reaction is 0.04 mol L-1 s-1 at 10 minutes and 0.03 mol L-1 s-1 at 20 minutes after initiation. Half life of the reaction is minutes. (Given 2 = 0.3010, 3 = 0.4771)

The half-life of radioisotope bromine - 82 is 36 hours. The fraction which remains after one day is 10-2. (Given antilog 0.2006 = 1.587)

Time required for completion of 99.9% of a First order reaction is times of half life (t1/2) of the reaction.