Two learners, Wade and Tang are working together on a project. They were asked by their teacher to assemble a galvanic cell that would produce a large enough voltage to light up a 1.5V bulb.
They are allowed to use two electrodes, one of which must be a zinc electrode. After having done the necessary calculations they finally agress on the second electrode.
When the second electrode is connected to positive terminal of the voltmeter , the voltmeter shows a reading of -2.11V.
But to their disappointment, Wade and Tang discover that the bulb won't light up
1) Which electrode is the cathode? The zine electrode or the 2nd electrode. Motivate answer
2) Identify the 2nd electrode.
The Attempt at a Solution
1) Ok i think the second electrode is the cathode. I believe so because it is connected to the postive end of the voltmeter.
2) E cell = Ecathode - Eanode
-2.11= Ecathode -(-0.76)
-Ecathode=2.11 + 0.76
Ecathode = -2.87
Therefore according to Table of standard reduction potential Ecathode is Cadmium.
The problem is face is that...how can cadmium be the Cathode as the cathode is were reduction takes place... should it be Zinc that gets reduced as it have a higher E value than cadmium?
So i just need to know how to approach this question and any other questions in the future..i am writing my prelim exam on monday and this question i still cant figure out..