# What is 'absorbance power' in electrochemistry?

I have been asked

$$\ce{250 mL}$$ solution of unknown molarity of $$\ce{CuSO4}$$ in water was electrolysed using platinum electrodes. After the passage of a current $$2 \times 10^{-3}$$ ampere for $$19.3$$ minutes, the absorbance power of $$\ce{CuSO4(\textrm{aq.})}$$ was reduced to $$50$$% of its original value. What was the molarity of $$\ce{CuSO4}$$?

My questions are the following:

• What is absorbance power?
• What does "the absorbance power of $$\ce{CuSO4(\textrm{aq.})}$$ was reduced to $$50$$% of its original value" mean in the context of this problem?

Note: I am not asking for the solution to this problem.

• Absorbance is directly proportional to concentration. To know what is absorbance read this: chem.libretexts.org/@go/page/3747 – Nisarg Bhavsar Jun 16 at 18:52
• There is no such thing as “absorbance power”, except, perhaps, for diapers. Whomever set the problem meant absorbance. – Ed V Jun 16 at 18:58

## 1 Answer

What is absorbance power?

Sadly there is nothing called absorbance power. The question setter might have made an mistake by writing absorbance power when they meant absorbance.

Absorbance is the ability of an solution to absorb radiations of a particular wavelength. It is defined as the logarithm of the ratio of the initial and final flux(intensity if container is symmetrical) of the radiation.

$$A=\log \frac{I_0}{I}$$

What does "the absorbance power of $$\ce{CuSO4_{(aq)}}$$ was reduced to 50% of its original value" mean in the context of this problem?

Absorbance of an solution is directly proportional to it's concentration. Thus by saying that the absorbance of the solution was reduced to half, the question gives you information that the concentration of the copper sulphate solution became half of the original after the current was passed for 19.3 minutes.

• Can the downvoter please mention the reason for the downvote? I am always open for improvements! :) – Nisarg Bhavsar Jun 17 at 3:01