[Joules23]

How would i go about separating a mixture of an Strong acid(soluble in water), sugar, and sand? im trying to find the mass of each item

To get rid of the sand i know to dissolve everything in water then filter out the sand. But i dont see how to separate the acid and sugar, i was thinking about titrating it with NaOH, finding equiv point then moles NaOH = moles acid...

[macman104]

How would i go about separating a mixture of an Strong acid(soluble in water), sugar, and sand? im trying to find the mass of each item

To get rid of the sand i know to dissolve everything in water then filter out the sand. But i dont see how to separate the acid and sugar, i was thinking about titrating it with NaOH, finding equiv point then moles NaOH = moles acid...

What is your strong acid.  Maybe there is a way to precipitate your anion.  For example, if your acid is something like HCl, then you could precipitate AgCl and figure out moles of Cl^- which would equal moles of acid.

EDIT:  Of course, you destroy your acid in the process...

[Guitarmaniac86]

The problem with titrating it against NaOH is that you are adding sodium.

I would think of somehow recrstallising the sugar solution because the acid in the water wont come out. Once the sand is filtered off, take the solution of strong acid and sugar and place in an organic solvent and place in a separating funnel. The sugar molecules should want to migrate into the organic layer (im going on a guess here because organic things tend to want to go into organic solvents. It doesnt help that sugar is water soluble), and the acid should stay dissolved in the water.

Let two layers form and get rid of the aqueous layer.

Take the organic layer and recrystalise the sugar.

This is just a guess, dont take my word for it. If I am wrong, feel free to correct me. (Its 3am in england, Im not really able to think straight).

(Im kinda thinking the acids would react with the solvent, I dont have much faith in what Ive just typed.)

[Joules23]

the acid is potassium hydrogen phthalate KHC8H4O4 , will anything precipitate with that?

[macman104]

No, not that I can think.  That's also an organic molecule which will have solubility in the organic phase, so even separating by organic separation may not work.  The only thought I have is seeing if the solubility between the sugar and the acid vary by pH.  Otherwise, column chromatography?  I'm not sure if this is a theoretical exercise, or if you actually need to carry this out.

[Joules23]

why does the solubility of an organic compound change when the pH changes?

[macman104]

why does the solubility of an organic compound change when the pH changes?

Well, the acidic groups of KHP (Potassium Hydrogen Phthalate) will be protonated or deprotonated at various pHs, and if they are charged (deprotonated) then they will have an increased solubility in the aqueous phase.  However, sugar has a decent solubility as well, so I'm not sure of a great solution to this.

[ARGOS++]

Dear Joules23;

Dissolve both, Sugar and KHPhthalate in as less as possible cold Water; lower the pH with conc. HCl (mit smallest Excess) and most Phthalic acid will already crystallise.
The aqueous Solution you can additionally extract with ‘precious’ little Diethyl ether, and finally adjust the pH of Phthalic acid with KHCO₃ to get the KHPhthalate (quantitatively) back.
The Sugar you may dry and crystallise.

Solubility Data:
Sugar:                ~200g / 100ml  Water 25° C
Phthalic acid:         0.6g / 100ml  Water 20° C
  “ from MSDS:     Soluble in Methanol, Diethylether;
                          Very slightly soluble in cold Water.


Good Luck!
                    ARGOS⁺⁺

[Joules23]

The only solution available in this experiment to us is NaOH