Question

In an experiment to determine the electrochemical equivalent (ECE) of copper using a copper voltameter the time current graph is as shown. If the mass deposited in 30 minutes is m grams, the ECE of copper, in g/C is

• A. $ \frac{m}{120} $
• B. $ \frac{m}{60} $
• C. $ \frac{m}{30} $
• D. $ \frac{m}{2} $

Answer 1

Answer: (A)

: Charge = current $ \times $ time. $ \therefore $ The area enclosed by the curve = charge The curve is a trapezium. Area of trapezium $ =\frac{1}{2}\times $ height $ \times $ (sum of parallel sides) $ \therefore $ Charge $ =\frac{1}{2}\times (100\text{ }mA)\times (30+10)\text{ }min $ or Charge $ =(50\times 40\times 60)mA\times sec $ or Charge $ =\frac{50\times 40\times 60}{1000}(A\times \sec ) $ $ Q=120 $ coulomb. By laws of electrolysis, $ \angle Q=m $ Or $ Z=\frac{m}{Q}=\frac{m}{120}\frac{gram}{coulomb}. $