# Chemical Forums

## Chemistry Forums for Students => High School Chemistry Forum => Topic started by: theowne on November 22, 2007, 08:08:09 PM

Title: Net ionic equations - CO2 and H20
Post by: theowne on November 22, 2007, 08:08:09 PM
In a net ionic equation, CO2 gas and H20 liquid are not split, are they?
Title: Re: Net ionic equations - CO2 and H20
Post by: LQ43 on November 22, 2007, 08:24:49 PM
I think I know what you mean and the answer is no,
but to be sure can you write out a reaction that you would get CO2 and H2O
Title: Re: Net ionic equations - CO2 and H20
Post by: theowne on November 22, 2007, 08:33:11 PM
I have one more question, but here's the equation I was thinking about.  We have to write net ionic equations:

5H2C2O4 + 3H2SO4 + 2KMnO4 -> 10CO2 + 8H2O + 2MnSO4 + K2SO4

Assuming that the CO2 and H20 don't split, the net ionic I got was:

5H2C2O4 + 6H(+) + 2MnO4(-) ..> 10CO2 + 8H20 + 2Mn(+2)

I put everything as (aq) except CO2 and H2O.

---

One more small qestion, I just want to confirm that I'm doing this right.  We have an equation which starts with FeSO4 and one result is Fe2(SO4)3, and I just want to confirm that when doing the net ionic, the Fe2 splits into an Fe with a positive 3 charge, rather than a positive 2 charge like the FeSO4 does.

Thanks!
Title: Re: Net ionic equations - CO2 and H20
Post by: LQ43 on November 22, 2007, 09:41:25 PM
I have one more question, but here's the equation I was thinking about.  We have to write net ionic equations:

5H2C2O4 + 3H2SO4 + 2KMnO4 -> 10CO2 + 8H2O + 2MnSO4 + K2SO4

Assuming that the CO2 and H20 don't split, the net ionic I got was:

5H2C2O4 + 6H(+) + 2MnO4(-) ..> 10CO2 + 8H20 + 2Mn(+2)

I put everything as (aq) except CO2 and H2O.

looks good, put the states of matter in for CO2 and H2O as well

One more small qestion, I just want to confirm that I'm doing this right.  We have an equation which starts with FeSO4 and one result is Fe2(SO4)3, and I just want to confirm that when doing the net ionic, the Fe2 splits into an Fe with a positive 3 charge, rather than a positive 2 charge like the FeSO4 does.

Thanks!

if you mean Fe2(SO4)3 dissociates into Fe3+  +   ...   and FeSO4 dissociates into Fe2+  +  .
you're doing this right
Title: Re: Net ionic equations - CO2 and H20
Post by: theowne on November 22, 2007, 10:00:27 PM
Thanks a lot for that.
Title: Re: Net ionic equations - CO2 and H20
Post by: theowne on November 22, 2007, 10:11:52 PM
Last one I promise, another problem I'm stuck on is why Iron Sulphate causes a faster rate of reaction than oxalic acid in the same reaction.  Looking at the ionic equations, it looks like it has to do with the breaking up of FeSO4 whereas the Oxalic acid does not do the same.  How to describe this in the way the question wants though?  I guess it takes more energy to split up the Oxalic acid rather than the Fe+2 and SO4-2 which split as ions in the solution? Does this mean the activation energy will be higher for the oxalic acid?  Thus affecting the rate of reaction?
Title: Re: Net ionic equations - CO2 and H20
Post by: LQ43 on November 22, 2007, 10:24:36 PM
so are you now looking at a 3rd redox rxn with oxalic acid and iron III sulfate? or are you comparing the two that you have already mentioned? pls clarify...
Title: Re: Net ionic equations - CO2 and H20
Post by: theowne on November 22, 2007, 10:26:00 PM
Same as before, except in the second scenario Oxalic acid has been replaced with Iron Sulphate.  In the Ionic equation for the new reaction, Fe and SO4 disassociate into ions while Oxalic does not.  I'm wondering if this is the reason for a dramatic difference in reaction rate (the FeSO4 one reacts instantly).

The question says to 'consider what must happen to the molecules before reactants can change to products'
Title: Re: Net ionic equations - CO2 and H20
Post by: LQ43 on November 22, 2007, 10:48:50 PM
Last one I promise, another problem I'm stuck on is why Iron Sulphate causes a faster rate of reaction than oxalic acid in the same reaction.  Looking at the ionic equations, it looks like it has to do with the breaking up of FeSO4 whereas the Oxalic acid does not do the same.  How to describe this in the way the question wants though?  I guess it takes more energy to split up the Oxalic acid rather than the Fe+2 and SO4-2 which split as ions in the solution? Does this mean the activation energy will be higher for the oxalic acid?  Thus affecting the rate of reaction?

yes I think you have the right idea, but maybe more of an entropy situation.
For oxalic acid which is a weak acid, there are fewer ions in solution for the redox to start and the weak acid equilibrium must be disturbed enough for more oxalate ions to be formed (Le Chatelier)
FeSO4 being ionic, many more ions in solution readily available for redox

- which is similar to what you are saying, different words
Title: Re: Net ionic equations - CO2 and H20
Post by: theowne on November 22, 2007, 10:51:41 PM
Okay, thank you for the assistance.