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 $=\frac{1}{2}\times (100mA)\times (30+10)min$ 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 $Z=\frac{m}{Q}=\frac{m}{120}\frac{gram}{coulomb}.$