My teacher performed two experiments under the fume hood with azinc-copper cell (we are studying electrochemical cells):
1) she added Na2S to Zn in the zn half cell of azinc-copper cell and then voltage went up.
2) She added Na2S to Cu in copper half cell then voltagewent down.
Q: Use Le Chatlier's principle as a reference to explainwhy these voltage changes occurred. Explain why they weredifferent!
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Okay...so I read my book and I sort of have an idea of howto answer this but I'd really like some more feedback andexplanation.
My answer so far: Voltage is described as potentialdifference. This is caused when electrons move from the anode tothe cathode (in this case, Cu = cathode while Zn = anode). In otherwords Zn is being oxidized because it loses electrons.
When you add Na2S to the Zn half-cell, you form theprecipitate ZnS. This means there's less Zn concentration (sincethe Zn went into the precipitate.) So, less electrons are availableto migrate to Cu. Because that would cause a decrease in voltage,the system tries to compensate by shifting equilibrium position toincrease voltage instead.
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I'm also just absolutely baffled as to why voltage goes down forthe Copper half. If I use the same reasoning as I did in #1 thenI'd just be contradicting myself...
My teacher performed two experiments under the fume hood with azinc-copper cell (we are studying electrochemical cells):
1) she added Na2S to Zn in the zn half cell of azinc-copper cell and then voltage went up.
2) She added Na2S to Cu in copper half cell then voltagewent down.
Q: Use Le Chatlier's principle as a reference to explainwhy these voltage changes occurred. Explain why they weredifferent!
--
Okay...so I read my book and I sort of have an idea of howto answer this but I'd really like some more feedback andexplanation.
My answer so far: Voltage is described as potentialdifference. This is caused when electrons move from the anode tothe cathode (in this case, Cu = cathode while Zn = anode). In otherwords Zn is being oxidized because it loses electrons.
When you add Na2S to the Zn half-cell, you form theprecipitate ZnS. This means there's less Zn concentration (sincethe Zn went into the precipitate.) So, less electrons are availableto migrate to Cu. Because that would cause a decrease in voltage,the system tries to compensate by shifting equilibrium position toincrease voltage instead.
--
I'm also just absolutely baffled as to why voltage goes down forthe Copper half. If I use the same reasoning as I did in #1 thenI'd just be contradicting myself...
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