October 9, 2015

Homework Help: college chem

Posted by mm on Monday, January 25, 2010 at 10:27pm.

A 1.10g- sample contains only glucose and sucrose . When the sample is dissolved in water to a total solution volume of 25.0ML , the osmotic pressure of the solution is 3.78atm at 298K

a.What is the percent by mass of glucose in the sample?

b.What is the percent by mass of sucrose in the sample?
pi = osmotic pressure = MRT
You know pi, R, and T, solve for M
Molarity = moles x L
You know L, solve for moles.
Here are the two equations.
X + Y = 1.10
(X/molar mass glucose) + (Y/molar mass sucrose) = moles.
Solve for X and Y, then you can determine percent of each.
Post your work if you get stuck.

im so lost on the same problem.
ok here is what i have done..

so mols for .025L is 2.9369
And you when i used the two equations i got lost.


and x/(180.162g/mol)+y/(342.308g/mol)=2.9362

i think i did this wrong. Please help!

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