Examples - Photochemistry Chemistry Notes | EduRev

Physical Chemistry

Chemistry : Examples - Photochemistry Chemistry Notes | EduRev

The document Examples - Photochemistry Chemistry Notes | EduRev is a part of the Chemistry Course Physical Chemistry.
All you need of Chemistry at this link: Chemistry

Problem. The carbon-14 activity of an old wood sample is found to be 14.2 disintegration min–1 g–1. Calculate age of old wood sample, if for a fresh wood sample carbon-14 activity is 15.3 disintegration min–1 g–1 (t1/2 carbon =14) = 5730 year), is

(1) 5000 year (2) 4000 year (3) 877 year (4) 617 year

Sol.     Act ivit y =  Examples - Photochemistry Chemistry Notes | EduRev

 k = rate constant 
and    NA = no. of atom
Activity of old wood = k Nold = 14.2 …(1)
Activity of new wood = k Nnew = 15.3 …(2)

From equation (1) & (2) we get

Examples - Photochemistry Chemistry Notes | EduRev

orExamples - Photochemistry Chemistry Notes | EduRev …(3)

We know that k × t1/2 = 0.693

Examples - Photochemistry Chemistry Notes | EduRev …(4)

We know that

i.e.Examples - Photochemistry Chemistry Notes | EduRev
Examples - Photochemistry Chemistry Notes | EduRev

T = 617 year

The correct answer is (4).


Problem. Using cuvettes of 0.5 cm path length, a 10–4 M solution of a chromphone shows 50% transmittance at certain wave length. The molar extinction coefficient of the chromphre at this wave length is (log 2 = 0.3010) 

(1) 1500 M–1 cm–1 (2) 3010 M–1 cm–1 (3) 5000 M–1 cm–1 (4) 6020 M–1 cm–1

Sol. 

Transmittance = T Examples - Photochemistry Chemistry Notes | EduRev

Absorbance = A = Examples - Photochemistry Chemistry Notes | EduRev

Examples - Photochemistry Chemistry Notes | EduRev
Examples - Photochemistry Chemistry Notes | EduRev

∈= 6020 M–1 cm–1

The correct answer is (4).

 

Problem. The rate law for one of the mechanisms of the pyrolysis of CH3CHO at 520°C and 0.2 bar is:
 Rate =  
Examples - Photochemistry Chemistry Notes | EduRev

The overall activation energy Ein terms of the rate law is:

(1) Ea(2) + Ea(1) + 2Ea(4)   (2)Examples - Photochemistry Chemistry Notes | EduRev   (3)Examples - Photochemistry Chemistry Notes | EduRev 
 (4) 
Examples - Photochemistry Chemistry Notes | EduRev

Sol.    Rate =   Examples - Photochemistry Chemistry Notes | EduRev

= koverall [CH3CHO]3/2
i.e.   Examples - Photochemistry Chemistry Notes | EduRev

Examples - Photochemistry Chemistry Notes | EduRev

i.e.
Examples - Photochemistry Chemistry Notes | EduRev

and
Examples - Photochemistry Chemistry Notes | EduRev

 

or Examples - Photochemistry Chemistry Notes | EduRev

Examples - Photochemistry Chemistry Notes | EduRev

The correct answer is (3).

Problem. In the Michaelis-Menten mechanism of enzyme kinetics, the expression obtained as

Examples - Photochemistry Chemistry Notes | EduRev

The value of k3 and k(Michaelis constant, mol L–1) are 

(1) 1.4 × 1012, 104 (2)1.4 × 108, 104 (3) 1.4 × 108, 10–4 (4) 1.4 × 1012, 10–4

Sol.  We know that Michaelis Menten equation is:

Examples - Photochemistry Chemistry Notes | EduRev…(1)

Examples - Photochemistry Chemistry Notes | EduRev
Examples - Photochemistry Chemistry Notes | EduRev

Multiply this equation by 
Examples - Photochemistry Chemistry Notes | EduRev

Examples - Photochemistry Chemistry Notes | EduRev

or              Examples - Photochemistry Chemistry Notes | EduRev                           …(2) 

and                Examples - Photochemistry Chemistry Notes | EduRev                       …(3)

Comparing equation (2) & (3) we get

i.e. Examples - Photochemistry Chemistry Notes | EduRev
and  Examples - Photochemistry Chemistry Notes | EduRev

k3 = 1.4 × 1012 × 10–4 

= 1.4 × 108
i.e. The correct answer is (3).

Problem. The Langunier adsorption isotherm is given by  Examples - Photochemistry Chemistry Notes | EduRev where P is the pressure of the adsorbate gas. The Langmuir adsorption isotherm for a diatomic gas Aundergoing dissociative  adsorption is 

(1) Examples - Photochemistry Chemistry Notes | EduRev   (2) Examples - Photochemistry Chemistry Notes | EduRev  (3) Examples - Photochemistry Chemistry Notes | EduRev   (4)Examples - Photochemistry Chemistry Notes | EduRev

Sol.  R(g) + M(surface) Examples - Photochemistry Chemistry Notes | EduRev     RM (surface)

then  Examples - Photochemistry Chemistry Notes | EduRev

if  R2(g) + 2M (surface)  Examples - Photochemistry Chemistry Notes | EduRev   2M (surface)

Examples - Photochemistry Chemistry Notes | EduRev

i.e. the correct answer is (4).

 

Problem. The overall rate of following complex reaction

Examples - Photochemistry Chemistry Notes | EduRev             (fast equilibrium)

Examples - Photochemistry Chemistry Notes | EduRev          (fast equilibrium)

Examples - Photochemistry Chemistry Notes | EduRev        (slow)

 

The steady state approximate would be 

(1) k1k2k3[A]3[B] 

(2) k1k2k3[A][B]3 

(3) k1k2k3[A][B]2 

(4) k1k2k3[A][B] 

Sol.  Examples - Photochemistry Chemistry Notes | EduRev         (fast equilibrium)

thenExamples - Photochemistry Chemistry Notes | EduRev…(1)

Examples - Photochemistry Chemistry Notes | EduRev          (fast equilibrium)

then   Examples - Photochemistry Chemistry Notes | EduRev    …(2)
Examples - Photochemistry Chemistry Notes | EduRev        (slow)

The rate of formation of product P is 

Examples - Photochemistry Chemistry Notes | EduRev…(3)

From equation (1) & (2) we get

&Examples - Photochemistry Chemistry Notes | EduRev

thenExamples - Photochemistry Chemistry Notes | EduRev
Examples - Photochemistry Chemistry Notes | EduRev

i.e. the correct answer is (1)

 

Problem. The species 19Ne and 14C emit a position and b-particle respectively. The resulting species formed are respectively

(1) 19Na and 14B (2) 19F and 14N (3) 19Na and 14N (4) 19F and 14

Sol. 
Examples - Photochemistry Chemistry Notes | EduRev

i.e. the correct answer is (b).
 

Problem. The half life of a zero order reaction (A → P) is given by (k = rate constant)

(1) Examples - Photochemistry Chemistry Notes | EduRev  (2)  Examples - Photochemistry Chemistry Notes | EduRev  (3) Examples - Photochemistry Chemistry Notes | EduRev  (4)   Examples - Photochemistry Chemistry Notes | EduRev

Sol.   

Examples - Photochemistry Chemistry Notes | EduRev

if t = t1/2 then

Examples - Photochemistry Chemistry Notes | EduRev

Thus
Examples - Photochemistry Chemistry Notes | EduRev
Examples - Photochemistry Chemistry Notes | EduRev

i.e. the correct answer is (1).

Offer running on EduRev: Apply code STAYHOME200 to get INR 200 off on our premium plan EduRev Infinity!

Related Searches

Previous Year Questions with Solutions

,

Viva Questions

,

past year papers

,

Examples - Photochemistry Chemistry Notes | EduRev

,

practice quizzes

,

Extra Questions

,

Objective type Questions

,

Semester Notes

,

Examples - Photochemistry Chemistry Notes | EduRev

,

shortcuts and tricks

,

mock tests for examination

,

MCQs

,

Examples - Photochemistry Chemistry Notes | EduRev

,

Exam

,

study material

,

Important questions

,

Summary

,

ppt

,

Sample Paper

,

Free

,

pdf

,

video lectures

;