Question

Another sample of KMnO4 solution has 80% of light of a given , passing through it was transmitted when a cell of 4 cm was used for the sample analysis and the molar absorptivity was 2. Show that the concentration is 0.05 g/L Calculate the transmittance and Absorbance if the %T is (a) 1% (b) 10% (c) 100% If 25.8 mg of Benzene is dissolved in 250 ml of solution that absorbed at 256 nm, with absorption coefficient or molar absorptivity of 201 M'cm' in a cell of 1.0 cm. Calculate the absorbance. 6. Calculate the Absorbance and Transmittance of 0.0024 M solution with € = 313 M'cm in a cell of 2 cm path length.

Answer 1

4. A= 2-log %T

where A= absorbance

T= Transmittance

Therefore (a) 1% T = 2-log 1= 2

(b) 10% T=2-log 10=1

(c) 100% T= 2-log 100=0

5. Absorbance
A = ECT
where $\varepsilon$ = molar absorption coefficient

c= concentration in g/L

x= path length

concentration c= mass/ volume=25.8/250=.1032 mg/ml

Absorbance A= 201$\times$1$\times$.1032 =20.7432

6. A=.0024 $\times$ 313 $\times$ 2 =1.5024

Absorbance = log(1/T)

Therefore Transmittance T=.222595