Sorry, I am just really confused about how to obtain this from my experiment. The experiment consisted of extracting caffeine from tea.
Basically
amount of tea leaves: 2.5347g
After steeping it, we centrifuged and placed it in a SPE column. Then, we conditioned it with methanol and water and afterwards with ethyl acetate.
It was then evaporated in a water bath
"crude caffeine": .051g
The caffeine was then sublimated and scraped off.
pure caffeine: .023g
The question asked for the percent recovery of the pure caffeine. Do I take .023 and divide by the crude caffeine or the tea leaves?
Also, to assist in my understanding for future cases, does this mean I can't do percent yield because a theoretical yield would need a reaction with moles provided, etc?
Basically
amount of tea leaves: 2.5347g
After steeping it, we centrifuged and placed it in a SPE column. Then, we conditioned it with methanol and water and afterwards with ethyl acetate.
It was then evaporated in a water bath
"crude caffeine": .051g
The caffeine was then sublimated and scraped off.
pure caffeine: .023g
The question asked for the percent recovery of the pure caffeine. Do I take .023 and divide by the crude caffeine or the tea leaves?
Also, to assist in my understanding for future cases, does this mean I can't do percent yield because a theoretical yield would need a reaction with moles provided, etc?
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Percent yield is easy once you know the definitions.
Percent yield is ACTUAL yield divided by THEORETICAL yield, x 100.
Actual yield is your experimental yield. It needs to be converted to moles.
Theoretical yield is the yield from the balanced stoichiometry equation, also in moles.
For example, if I'm making table salt, the balanced equation is: 2Na + Cl2 --> 2NaCl
Therefore, the theoretical yield is 2 moles, because that's what the equation makes.
Say I make 1.3 moles in an experiment. That's my actual yield.
To find my percent yield, actual/theoretical x 100 = 1.3/2 = 0.65 (x 100) = 65% yield!
It's that easy.
For your problem all you have to do is find the balanced stoichiometry and convert your actual yield to moles (it'll be a tiny number!)
Molar mass of caffeine is 194.2grams.
.023g(1mol/194.2g) = .023/194.2 = 1.2x10^-4 mol
I couldn't find any stoichiometry equations for caffeine. Hopefully your prof gave you one with the lab.
Good luck!
Percent yield is ACTUAL yield divided by THEORETICAL yield, x 100.
Actual yield is your experimental yield. It needs to be converted to moles.
Theoretical yield is the yield from the balanced stoichiometry equation, also in moles.
For example, if I'm making table salt, the balanced equation is: 2Na + Cl2 --> 2NaCl
Therefore, the theoretical yield is 2 moles, because that's what the equation makes.
Say I make 1.3 moles in an experiment. That's my actual yield.
To find my percent yield, actual/theoretical x 100 = 1.3/2 = 0.65 (x 100) = 65% yield!
It's that easy.
For your problem all you have to do is find the balanced stoichiometry and convert your actual yield to moles (it'll be a tiny number!)
Molar mass of caffeine is 194.2grams.
.023g(1mol/194.2g) = .023/194.2 = 1.2x10^-4 mol
I couldn't find any stoichiometry equations for caffeine. Hopefully your prof gave you one with the lab.
Good luck!