Question

How do I determine the molar absorptivity value of copper sulfate pentahydrate at 395nm without the given absorbance? The copper sulfate pentahydrate is 0.200M. I'm assuming we use some derivation of beer's law

Answer 1

The absorbance of copper sulfate pentahydrate is not provided. However, it is easy to measure the transmittance of the sample. The transmittance of a sample is defined as the ratio of the light transmitted by the sample to the light incident on the sample.

T = I/I₀

%T = 100T

where I = intensity of the light transmitted by the sample and

I₀ = intensity of the light incident on the sample.

The absorbance of the sample is related to the transmittance as

A = 2 – log (%T)

where A denotes the absorbance of the sample.

The transmittance of the sample of copper sulfate pentahydrate can be measured and the absorbance can be derived from the above relation.