What is the molality of 85% phosphoric acid, H3PO4, if the density of the soluti

[Tina324]

of the solution is 1.7 g/ml?

thanksss

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[joonkimdds]

huh??

 

[Ruthless]

i believe it may be 57.8mol/kg

 

[Neil45]

I could be wrong, but I will give it my best shot.

85% phosphoric acid could translate to 85g of H3PO4/ 100mL of solution.

So,

(85 g H3PO4/ 100 mL solution) * (mol/98g H3PO4) * (mL/ 1.7 g) * (1000g/ 1kg)= 5 m

Is 5 m the answer? I didn't use a calculator, so the real answer might be off a little bit.

 

[utdent20]

I am up with Neil.. that is what i was bout to post.

 

[klutzy1987]

I am up with Neil.. that is what i was bout to post.

This question is straight out of achiever i think. Their answer given was incredibly stupid. If you look there are two things there that cancel out and the answer is much more straight forward than the achiever suggests.

 

[klutzy1987]

85% H3PO4 means that (85 g H3PO4/15 g H2O). Therefore just do dimentional analysis and
(85 g H3PO4/15 g H2O) * (1000g/1kg) * (1 mol H3PO4/98 g H3PO4).

This gives you moles of solute per kg of solvent, or molality.

57.8m

You do not even need to use the density in the problem, just achiever is so boneheaded that their solution has density. Shows how crappy achiever is.

 

[Ruthless]

Kultz, i agree with you about the answer but are u 100% it is the right one.

 

[ucla2134]

of the solution is 1.7 g/ml?

thanksss

hi, i got only 14.89 m. What is the answer though? THanks

 

[Tina324]

yup klutzy is right 57.8.

hmm i understand you, BUT the density throws me off. So the density plays now role is figuring out this question?