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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: THC on February 11, 2008, 03:32:24 AM

Title: Which reaction is most likely to occur? Halogens
Post by: THC on February 11, 2008, 03:32:24 AM
Which reaction is most likely to occur?

2 F- + Cl2 -> F2 + 2 Cl-
or
2 Cl- + F2 -> Cl2 + 2 F-

Do I calculate the electrode potential E^0 for each reaction and compare? This is not an electrochemical reaction, so maybe not?
Title: Re: Which reaction is most likely to occur? Halogens
Post by: 0000000 on February 11, 2008, 07:26:32 AM
2 Cl- + F2 -> Cl2 + 2 F-

because the F have greater attraction to the electrons, but just to mention that the reaction it's not so simply.
Title: Re: Which reaction is most likely to occur? Halogens
Post by: THC on February 11, 2008, 08:01:10 AM
Quote from: Tomce on February 11, 2008, 07:26:32 AM
2 Cl- + F2 -> Cl2 + 2 F-

because the F have greater attraction to the electrons, but just to mention that the reaction it's not so simply.

I just wondered, what about calculating dG for both reactions and compare?
Title: Re: Which reaction is most likely to occur? Halogens
Post by: 0000000 on February 11, 2008, 11:10:42 AM
Quote from: THC on February 11, 2008, 08:01:10 AM
Quote from: Tomce on February 11, 2008, 07:26:32 AM
2 Cl- + F2 -> Cl2 + 2 F-

because the F have greater attraction to the electrons, but just to mention that the reaction it's not so simply.

I just wondered, what about calculating dG for both reactions and compare?

OK you can do that and you will get the same conclusion, but in cases like this think about the electronegative coefficients first
Title: Re: Which reaction is most likely to occur? Halogens
Post by: DevaDevil on February 11, 2008, 04:20:43 PM
F2(g) + 2e− → 2F−(aq)    E0 = +2.87 V
Cl2(g) + 2e− → 2Cl−(aq)    E0 = +1.36 V

reduction potential for fluor is highest, which means it will be the reduced species, so indeed:

2 Cl- + F2 -> Cl2 + 2 F- (E0, cell = 2.87 - 1.36 = 1.21 V ) is the preferred reaction.
Title: Re: Which reaction is most likely to occur? Halogens
Post by: THC on February 12, 2008, 12:30:41 AM
Quote from: Tomce on February 11, 2008, 11:10:42 AM

OK you can do that and you will get the same conclusion, but in cases like this think about the electronegative coefficients first
Yes, that's probably what my teacher expected.

Thanks to both of you!