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Topic: Chemistry Molarity Lab Question  (Read 4490 times)

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Offline Gweedo8

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Chemistry Molarity Lab Question
« on: July 03, 2009, 03:11:59 PM »
I have this long online lab that I am working on and I am stuck on converting Molarity then ultimately finding the % of phosphoric acid in the cola? There is all of different steps I went through with information but I am going to try to give only the info needed to help me out. (hopefully I do not miss any)

Coca-cola contains acids including carbonic acid which is formed from the dissolution of the carbon dioxide in the water, and phosphoric acid, which is used to give it a little “kick” when you are drinking it. 

The chemical reactions for the titrations of the acids are given below.
 
H2CO3(aq)  + 2NaOH(aq) → Na2CO3(aq) + 2H2O(l)
H3PO4(aq) + 3NaOH(aq) → Na3PO4(aq) + 3H2O(l)

My unanswered questions:

Give the molarity of phosphoric acid in the original cola?
What is the density of the cola?
What is the % phosphoric acid in the cola?

Some helpful data:

Pipet 2.0mLs of the decarbonated cola into a 100mL volumetric flask.  Add 10mLs of the ammonium molybdate/vandate solution and fill to the mark with distilled water.  This will be your unknown.

Using McVc=MdVc, calculate the molarity of phosphate in the original cola. The answer was .0063 using
Mc=?
Vc=2.0mLs
Md=.00126
Vd=100

If this is not enough info can you please let me know what I am missing and I will re post with more info.

Thank you

Offline Borek

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Re: Chemistry Molarity Lab Question
« Reply #1 on: July 03, 2009, 04:04:05 PM »
You are asking very similar question for the third time. We have no idea what Mc or Vc (nor Vd or Md) are - I could guess, but I doubt it wasn't explained or at least suggested somewhere.
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