How much copper will be deposited from a vitriol solution in 3 minutes, if the current through the electrolyte changes in accordance with the law `i=6-0.03t`? All quantities are expressed in the SI system.

Answer

200 mg.

Explanation

First find the charge passing through the solution, making use of the graph in Fig. Since the current changes linearly, the eventual value being `i_(ev)=6-0.03xx180=2.4A,` the charge is easily obtained : `q=(i_(0)+i_(ev))t//2`. Incidentally, the same result may be obtained by integration the expression
`q=underset(0)overset(180)intidt`
(check this). Then the mass of copper may be found from Faraday.s law