# Chapter 9 Photochemistry¶

## Example 9_1 pgno:634¶

In :
from math import log10
print'Let M be the Molecular weight of the dye.Original concentration is 30.1/M mol litre**-1'
I0=100.;
I=50.;
b=1.;
A=log10(I0/I);
print'\nFrom Beers law=A=',A
x=A/30.1;
print'\na/M=',x
c=15.05;
I=70.7;
print'\nPercentage of light transmitted=I=',I
AI=100-I;
print'\nPercentage of light absorbed=AI=',AI
c=60.2;
I=25;
print'\nPercentage of light transmitted=I=',I
AI=100-I;
print'\nPercentage of light absorbed=AI=',AI
print'\nIt must be noted that it is absorbance A that is linearly related to concentration and not percentage light transmitted or absorbed'
b=2;
c=30.1;
I=25;
print'\nPercentage of light transmitted=I=',I
b=4.32;
print'\nb=cm',b

Let M be the Molecular weight of the dye.Original concentration is 30.1/M mol litre**-1

From Beers law=A= 0.301029995664

a/M= 0.0100009965337

Percentage of light transmitted=I= 70.7

Percentage of light absorbed=AI= 29.3

Percentage of light transmitted=I= 25

Percentage of light absorbed=AI= 75

It must be noted that it is absorbance A that is linearly related to concentration and not percentage light transmitted or absorbed

Percentage of light transmitted=I= 25

b=cm 4.32


## Example 9_2 pgno:638¶

In :
c=3*10**10;#velocity of light in cm#
h=6.625*10**-27;#plank's constant#
l=3020*10**-8;#wavelength of light radiation in cm#
E=(L*h*c)/l;#value of one einstein in ergs#
print'Value of one einstein=E==3.96*10**12ergs',E
LA=15000.;#light absorbed in ergs per second#
NE=LA/E;#number of einsteins absorbed per second#
print'\nNumber of Einsteins absorbed per second=NE=3.788*10**-9'
QY=0.54;#Quantum yield for CO formation#
N=QY*NE;#number of moles of CO formed per sec#
print'\nNumber of moles of Co formed per sec=N=2.046*10**-9'
R=2.046*10**-9;#Rate of formation of CO in moles per sec#
print'\nRate of formation of CO= moles per sec',R

Value of one einstein=E==3.96*10**12ergs 3.96183774834e+12

Number of Einsteins absorbed per second=NE=3.788*10**-9

Number of moles of Co formed per sec=N=2.046*10**-9

Rate of formation of CO= moles per sec 2.046e-09