Question

If a 0.10 M solution of a colored substance has a maximum absorbance at 500 nm and an absorbance of 0.26 at this wavelength, what will be the measured absorbance of a 0.20 M solution at 500 nm?

Answer 1

Answer : The measured absorbance of 0.20 M solution is 0.52

Explanation :

Using the proportionality relationship between concentration and absorbance, we use:

`(C_1)/(C_2)=(A_1)/(A_2)`

where,

`C_1` = concentration of solution 1 = 0.10 M

`C_2` = concentration of solution 2 = 0.20 M

`A_1` = absorbance of solution 1 = 0.26

`A_2` = absorbance of solution 2 = ?

Now put all the given values in the above expression, we get:

`(0.10M)/(0.20M)=(0.26)/(A_2)`

`A_2=0.52`

Therefore, the measured absorbance of 0.20 M solution is 0.52

Answer 2

The absorbance at 500 nm is
`A_2 = 0.52A`

Step-by-step explanation:

BY USING proportionality relationshiop between concentration and absorbance , which is given as

`(c_1)/(c_2) =(A_1)/(A_2)`

FROM THE DATA WE HAVE

`c_1 = 0.10 M`

`A_1 = .26A`

`c_2 = 0.20 M`

so, from above relation we have

`A_2 = (c_2 A_1)/(c_1)`

`A_2 = (0.20*0.26)/(0.10)`

`A_2 = 0.52A`