Question

4. (a) Explain the term electrodes in electric cells.
(b) An electric current passing through an electrolyte for 2 minutes deposited 200g of a substance. If the electrochemical equivalent of the substance is 8.33×10⁻⁴gC⁻¹, calculate the current that passed.

Accepted Answer

(a) Electrodes are conductors (usually metal or graphite rods/plates) through which electric current enters or leaves an electrolyte or other medium during electrolysis or in a cell. The electrode where current enters the electrolyte is the anode; the electrode where current leaves is the cathode.

(b) m = zIt, so I = m/(zt). Given m=200g, z=8.33×10⁻⁴ g/C, t=2min=120s. I = 200/(8.33×10⁻⁴×120) = 200/0.09996 ≈ 2000A. (Note: this very large current value arises directly from the given figures in the source question.)

WAEC Physics 2012 Theory — Question 4

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