What is the concentration of KMnO4 solution in mole/litre which gives an absorbance of 0.120 when measured in a 2.0 cm cell ?

Question –

What is the concentration of KMnO₄ solution in mole/litre which gives an absorbance of 0.120 when measured in a 2.0 cm cell ?

Solution –

A = Ɛ C l

A = absorbance 

Ɛ = molar extinction coefficient = 1.8 x 104 litre / mole cm

C=  concentration of KMnO₄ in mole/litre

l = 2.0 cm

A = 0.120

0.120 = 1.8 x 104 x C x 2

C= 0.120/ 1.8 x 104  x 2

C= 0.033 x 10-4 = 3.3 x 10^-6 mole/litre