Posted by **Lauren** on Wednesday, February 6, 2008 at 10:27pm.

Caffeine C8H10N4O2, is a stimulant found in a tea and coffee. A sample of the substance was dissolved in 45.0g of choloroform CHCl3 to give a 0.0946m solution. How many grams of caffine were in the sample.

m = molality

- Chemistry -
**drbob222**, Wednesday, February 6, 2008 at 10:30pm
molality = m = mols/kg solvent.

mols = g/molar mass.

You have kg and m so use equation 1 to solve for mols.

then go to equation 2, plug in mols and molar mass and solve for grams.

- Chemistry -
**Lauren**, Wednesday, February 6, 2008 at 10:35pm
ok i know how to figure out the 2nd equation

45.0g CHCl3(1 mols/118gCHCl3)=.381 mols CHCl3

but how do you get molarity. with kg solvent

- Chemistry -
**drbob222**, Wednesday, February 6, 2008 at 11:25pm
You wrote a small m when you posted the question initially. m = molality not molarity.

Look at the definition I wrote above.

m = mols/kg solvent.

m(of caffeine) = mols caffeine/kg solvent

0.0946 = mols caffeine/0.045 kg CHCl3.

mols caffeine = ??

The g caffeine = mols carreine x molar mass caffeine = xx

check my work. (By the way, the molar mass CHCl3, which is not needed, is 119.4).

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