Question

Absorbance values for five standard solutions of a colored solute were determined at 410 nm with a 1.00?cm path length, giving the following table of data:

Solute concentration (M)	A
0.250	0.175
0.500	0.350
0.750	0.525
1.000	0.700
1.250	0.875

Determine the absorbance values you would expect for solutions with the following concentrations:

0.4 M



0.6 M



0.8 M



1.1 M



Caluclate the average molar absorptivity of the compound: ____ 1/M*cm

Answer 1

For the given data

Absorbance when concentration (C2) = 0.4 M

Using,

A2 = A1 x C2/C2

A1 and C1 be absorbance and concentration from the data table

So,

absorbance for 0.4 M solution = 0.35 x 0.4 M/0.5 M = 0.28

--

Absorbance when concentration (C2) = 0.6 M

Using,

A2 = A1 x C2/C2

A1 and C1 be absorbance and concentration from the data table

So,

absorbance for 0.4 M solution = 0.35 x 0.6 M/0.5 M = 0.42

--

Absorbance when concentration (C2) = 0.8 M

Using,

A2 = A1 x C2/C2

A1 and C1 be absorbance and concentration from the data table

So,

absorbance for 0.4 M solution = 0.525 x 0.8 M/0.75 M = 0.56

--

Absorbance when concentration (C2) = 1.1 M

Using,

A2 = A1 x C2/C2

A1 and C1 be absorbance and concentration from the data table

So,

absorbance for 0.4 M solution = 0.7 x 1.1 M/1.0 M = 0.77

Average molar absorptivity = (0.525 - 0.350)/(0.75 - 0.50)

                                           = 0.700 M-1.cm-1