Science Buddies: "Ask an Expert"

hello,
I am preforming an experiment that deals with extracting caffeine from a roasted coffee bean using ethyl acetate.
I found a similar study online and when dealing with the amounts of the ethyl it says the mole fraction of it in the solvent times 10^3 is 9.946 (which means it is 0.00946).

I understand the mole fraction is the mass of the ethyl in moles divided by the mass of the solvent (the ethyl+the caffeine).
Im using 1 gram of coffee beans- 0.0084g of caffeine- I converted that to moles and got 0.00004325647 moles.
I then did the math (moles of ethyl divided by (moles of ethyl+moles of caffeine)= mole fraction) and got that the mass of the ethyl in moles should be : 4.8065226, when I converted that back to grams I got 423.47924703008823 grams (of ethyl acetate).

I don't know if my calculations were right and would love to hear feedback and get some help .

have a great day

**I am attaching the study I mentioned and a picture of my calculations
the study: http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0327-07932010000300012

Hi Carmel123,

You have correctly converted the mass that you mentioned for caffeine to moles. And you correctly calculated the mass of ethyl acetate from the number of moles that you posted.

Unfortunately I am not able to follow your mole fraction calculations. The attached file seems to be empty. The link goes to a search page and not the study that you mentioned.

You mention that the mole fraction of ethyl acetate is 0.009946 but this seems to be a tiny fraction for the solvent in a two component solution. Are you sure this value is correct? Does your solution contain only ethyl acetate and caffeine?

I did find some example mole fraction calculations that you may find useful at the following link:

http://www.softschools.com/formulas/che ... rmula/127/


I hope this helps. Please post again if you have more questions.

A. Norman