posted by Anonymous .
Please help, I have been trying to figure this out for some time:
For a lab I dissolved Calcium chloride with sodium carbonate each in water, then poured them into a funnel and filtered out a white pigment. I need to calculate the percent yield, but what is the white pigment. Is it calcium carbonate, sodium chloride, or something else?
The white precipitate, insoluble in the solvent, is calcium carbonate. The NaCl is soluble, CaCl2 is soluble, and Na2CO3 is soluble.
ok thank you with that part, but I still don't understand how I find the percent yield
You should have dried the precipitate (ppt) and weighed it. I don't know how carefully the experiment was controlled but I would have weighed the paper first so I could subtract the mass of the paper from the mass of the paper+ppt. At any rate, this gives you the ACTUAL yield.
The theoretical yield is calculated from stoichiomtery.
Na2CO3 + CaCl2 ==> 2NaCl + CaCOO3.
I assume you know how much Na2CO3 OR how much CaCl2 you started with. Either a weight of one or both or a molarity and volume of one or both. CaCulate the theoretical yield from that, then
percent yield = (actual yield/theoretical yield)*100