Aamc 9 #30

[the prodogy]

Advertisement - Members don't see this ad

I have a question for AAMC 9 #30. Its the question on emf that goes:

What is the standard emf for the galvanic cell in which the following overall reaction occurs?

2Na(s) + Cl2(g) --> 2Na+(aq) + 2Cl-(aq)

Given is:

half reaction E red (V)
Na+(aq) + e- -> Na(s) -2.71
Cl2(g) + 2e- -> 2Cl-(aq) +1.36

I know that you add the two half reactions, but since there are two Na used and is given to you in the opposite direction, wouldn't you have (2 x 2.71) + 1.36? Or does the amount of Na used in the reaction not matter cause the final answer they came up with was +4.07.

 

[gtr45]

no when calculating emf you DONT multiply by the coeffeicient ever. final answer of 4.07 is correct because u add 2.71 (reverse the value because Na is being oxidized) to 1.36. you dont multiply by the value because the number of moles doesnot effectthe reduction ptoential or emf.

 

[labellefille]

didn't i answer this question yesterday? did you not believe me?

 

[the prodogy]

didn't i answer this question yesterday? did you not believe me?

Hahaha... I know i posted it yesterday, but I couldn't find it. So I posted it again. Sorry for wasting space... but i still cant find the older post