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# Half cells watch

1. Hey, I'm really stuck on a question about combining half cells
Firstly I combined the two half cells I was given;

F2(g) + 2e- ----> 2F- (aq) E = +2.87 V
2H+ (aq) + 2e- -----> H2 (g) E = 0.00 V

As far as I know, you have to flip the hydrogen half cell?
that would give;

H2 (g)------> 2H+ (aq) + 2e-

Then the overall equation would be;

F2 (g) + H2 (g) ---> 2H+ (aq) + 2F-(aq)

Now..... Is that right?
Hey, I'm really stuck on a question about combining half cells
Firstly I combined the two half cells I was given;

F2(g) + 2e- ----> 2F- (aq) E = +2.87 V
2H+ (aq) + 2e- -----> 2H2 (g) E = 0.00 V

As far as I know, you have to flip the hydrogen half cell?
that would give;

2H2 (g)------> 2H+ (aq) + 2e-

Then the overall equation would be;

F2 (g) + 2H2 (g) ---> 2H+ (aq) + 2F-(aq)

Now..... Is that right?
It's not balanced.. count the hydrogens
3. (Original post by charco)
It's not balanced.. count the hydrogens
Ooops! that's me typing it wrong :P

But minus that, is that right or not?
Ooops! that's me typing it wrong :P

But minus that, is that right or not?
Apart from that it's OK

F2(g) + H2(g) ---> 2H+ (aq) + 2F-(aq)
5. Chemistry reference.... oh wait!
6. (Original post by joe3469)
Chemistry reference.... oh wait!
huh?
7. (Original post by charco)
Apart from that it's OK

F2(g) + H2(g) ---> 2H+ (aq) + 2F-(aq)

cool, okay.
What do you know about the Nernst equation?
huh?
Don't worry
cool, okay.
What do you know about the Nernst equation?
What do you want to know?
10. (Original post by charco)
What do you want to know?
Okay, I'm trying to calculate the E-cell of the reaction above yeah?
I've got the concentrations of the hydrogen and fluorine ions (0.4 mol dm-3 and 0.3 mol dm-3 respectively)
How would you work out Q?

Since as far as I know it is normally calculated by dividing one by the other, but I couldn't seem to do it in this cell?

If that makes sense?

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