Chemistry High school help | Tuontoes | Page 1

verbal nymph Jul 30, 2023, 5:55 AM

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Guys why is the answer A and not B? I though simple cell so effervescence only occurs at copper :/

wispy junco Jul 31, 2023, 11:08 AM

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Hey! I might be able to help you with that 🙂 I assume you already had the topic about redox-potential.
So for the first case, you can assume that the bubbling is caused by the oxidation of the metal. Zinc's standard reduction potential (E(Zn2+/Zn)= -0.76) is lower than 0 hence the oxidation of Zn will occur spontaneously. Copper's potential (E(Cu2+/Cu)= 0.32) is above 0 and will therefore not be oxidized by sulfuric acid. The Zn rod will slowly start to dissolve due to oxidation and we see the formation of hydrogen in form of bubbles.

For the second case, the metal rods touch each other. The potential will equilibrate in the two rods and we have a new standard reduction potential ( E(total)= 0.32 + (-0.76)= -0.44). As you can see, the total reduction potential is below zero for both rods now. That's why we can see bubbles surrounding both rods. The key point here is really that when the rods touch, the electrons can freely move between the rods and thus have a new standard potential.

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I'm not sure if I explained it a bit too difficult but just imagine Cu is not reactive enough and will therefore not react with sulfuric acid. Whereas Zn alone is reactive enough. When the rods touch, they have a new reactivity which will react with sulfuric acid.

verbal nymph Jul 31, 2023, 11:12 AM

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OMG TYSMM

wispy junco Jul 31, 2023, 11:13 AM

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You're welcooome

verbal nymph Jul 31, 2023, 11:14 AM

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Omg how old are u ur such a genius XD

wispy junco Jul 31, 2023, 11:19 AM

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Haha I'm already 22 but I'm a graduate student in chemistry :')

#Chemistry High school help