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-   -   Solution stoichometry, attempted ANSWER IS WRONG, can anyone fix answer (http://www.physicsforums.com/showthread.php?t=403312)

land_of_ice May14-10 09:22 PM

solution stoichometry, attempted ANSWER IS WRONG, can anyone fix answer
 
A 15.0 mL sample of an unknown H3PO4 solution requires 110 mL of 0.120 M KOH to completely react with the H3PO4 according the following reaction.

H3PO4 + 3KOH --------> 3H20 + K3PO4

What was the concentration of the unknown H3PO4 solution?

______________________________________

This SEEMED correct way to start problem, as it turns out this is not how to set up the problem, (attempt at doing the problem) : 15mL converted that to L , got 0.015 L, then multiplied that by .12 moles of the solute KOH divided by 1 Liter of the solution H3PO4, used the mole to mole conversion 3 moles of KOH to every 1 mole of H3PO4 and got the wrong answer. It's supposed to be
.293 Molarity.

??????

gabriels-horn May14-10 11:38 PM

Re: solution stoichometry, attempted ANSWER IS WRONG, can anyone fix answer
 
Quote:

Quote by land_of_ice (Post 2717904)
A 15.0 mL sample of an unknown H3PO4 solution requires 110 mL of 0.120 M KOH to completely react with the H3PO4 according the following reaction.

H3PO4 + 3KOH --------> 3H20 + K3PO4

What was the concentration of the unknown H3PO4 solution?

______________________________________

This SEEMED correct way to start problem, as it turns out this is not how to set up the problem, (attempt at doing the problem) : 15mL converted that to L , got 0.015 L, then multiplied that by .12 moles of the solute KOH divided by 1 Liter of the solution H3PO4, used the mole to mole conversion 3 moles of KOH to every 1 mole of H3PO4 and got the wrong answer. It's supposed to be
.293 Molarity.

??????

You have to do the three dissociation reactions separately.

Borek May15-10 04:11 AM

Re: solution stoichometry, attempted ANSWER IS WRONG, can anyone fix answer
 
Quote:

Quote by land_of_ice (Post 2717904)
15mL converted that to L , got 0.015 L, then multiplied that by .12 moles of the solute KOH

15 mL is the volume of acid, not base.

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