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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: kettles on March 05, 2012, 07:34:45 pm

Title: easy chemical equation question
Post by: kettles on March 05, 2012, 07:34:45 pm
The titration of an aqueous solution of phosphoric acid with an aqueous solution of potassium hydroxide was carried out to an indicator end point.

Would H3PO4(aq)+3KOH(aq)=>K3PO4(aq)+3H2O(l)

OR

H3PO4(aq)+2KOH(aq)=>K2HPO4(aq)+2H2O(l)

be the correct equation?
Title: Re: easy chemical equation question
Post by: Somye on March 05, 2012, 08:01:31 pm
I'm not precisely sure, but i think when doing titration equations you're supposed to assume full ionisation?

so in that case, it would be the first one, but then again, in reality it's very unlike to have all three protons fully ionised...

Someone else should be able to clarify a little further..
Title: Re: easy chemical equation question
Post by: Shenz0r on March 05, 2012, 08:08:42 pm
I think you assume full ionisation, the strength of the acid should not affect the amount of titrant required. All it does is donate protons slower I think...

So I guess it should be the first one.

*Confidence level = 60%
Title: Re: easy chemical equation question
Post by: Somye on March 05, 2012, 08:19:51 pm
Quote from: Shenz0r on March 05, 2012, 08:08:42 pm
I think you assume full ionisation, the strength of the acid should not affect the amount of titrant required. All it does is donate protons slower I think...

So I guess it should be the first one.

*Confidence level = 60%

Yeah +1, my confidence levels pretty much echo his
Title: Re: easy chemical equation question
Post by: Nobby on March 05, 2012, 08:23:45 pm
KOH is a strong base so I think it would fully deprotonate H3PO4 anyway
Title: Re: easy chemical equation question
Post by: pi on March 05, 2012, 08:30:54 pm
Quote from: Nobby on March 05, 2012, 08:23:45 pm
KOH is a strong base so I think it would fully deprotonate H3PO4 anyway

I don't think so (I may be wrong though). Having said that, this is a really poor question if that is all the info you are given.