Question

The UVA 254 of a leachate sample is determined to be 13.2 cm^-1 . If the sample is diluted tenfold with pure water, what fraction of UV radiation intensity would penetrate a 2 inch path through this leachate? Use scientific notation for your answer.

Answer 1

UVA 254 is a method to find the quality of water.

It is the amount of UV light of 254 nm absorbed by the sample as it travels through it.

Here, it is given to be 13.2 cm^-1

This means that the intensity reduces by a quantity

given by the equation

by the time the light travels a distance of x cm through the medium.

Now, the UVA is directly proportional to the molar concentration.

Here, the molar concentration has decreased by a quantity of 1/10 (ten fold dilution)

So, for the new sample, the UVA is 1.32 cm^-1

The fraction of radiation that penetrates a distance of x is then given by

Here, x = 2 inches.

But the unit should be in cm.

So, x = 2*2.54 = 5.08 cm

So,