How to determine anode and cathode in 6.57?

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Tiffany Chao 2H
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Joined: Fri Aug 09, 2019 12:17 am

How to determine anode and cathode in 6.57?

Postby Tiffany Chao 2H » Sun Mar 01, 2020 7:26 pm

6.57: 6.57 Use the data in Appendix 2B and the fact that, for the half- reaction F2(g) + 2 H+ (aq) + 2 e- --> 2HF (aq), E* = + 3.03 V, to calculate the value of Ka for HF.

Based on F2 (g) + 2 e- --> 2F-, E*= +2.87V, how am I suppose to know which one is the cathode and anode?

Thanks

Adam Kramer 1A
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Re: How to determine anode and cathode in 6.57?

Postby Adam Kramer 1A » Sun Mar 01, 2020 7:32 pm

this is the half-reaction for the cathode. We know this because there are electrons being added to the reactants, reducing the Fluorine.

JonathanS 1H
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Re: How to determine anode and cathode in 6.57?

Postby JonathanS 1H » Sun Mar 01, 2020 7:34 pm

Because you are given Eo for the whole reaction, we can use Eo = Ecathode - Eanode, all we need is the E value for the other half reaction and arrange the equation to give us the given Eo value.

Tiffany Chao 2H
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Joined: Fri Aug 09, 2019 12:17 am

Re: How to determine anode and cathode in 6.57?

Postby Tiffany Chao 2H » Sun Mar 01, 2020 8:19 pm

Adam Kramer 1A wrote:this is the half-reaction for the cathode. We know this because there are electrons being added to the reactants, reducing the Fluorine.

Sorry I meant F2 (g) + 2 e- --> 2F- is the cathode and F2(g) + 2 H+ (aq) + 2 e- --> 2HF (aq) is the anode according to the solutions manual. It says the E*cell = -0.16V
Last edited by Tiffany Chao 2H on Mon Mar 02, 2020 8:32 pm, edited 2 times in total.

Chris Charton 1B
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Re: How to determine anode and cathode in 6.57?

Postby Chris Charton 1B » Sun Mar 01, 2020 9:42 pm

The cathode will be the reaction with the larger E* value.

Natalie Benitez 1E
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Re: How to determine anode and cathode in 6.57?

Postby Natalie Benitez 1E » Sun Mar 01, 2020 9:52 pm

The cathode should be the one with the larger E value.

Emily Burghart 1k
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Re: How to determine anode and cathode in 6.57?

Postby Emily Burghart 1k » Sun Mar 01, 2020 10:08 pm

Natalie Benitez 1E wrote:The cathode should be the one with the larger E value.


Why again is the cathode the one with the larger E value?


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