% yield confusion

[californiamed]

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This was a ? in tbr, forgot which passage, but -- if you have 10 grams of Ca(OH2), how many grams of CaCO3, if it is 95% yield.

Ca(OH)2+CO2 ---> CaCO3 + H20

1) What does it mean by 95% yield? When doing % yield questions, it's usually the other way around - i.e. "what is the % yield). So i'm confused on how to approach this problem backwards?

 

[Jepstein30]

This was a ? in tbr, forgot which passage, but -- if you have 10 grams of Ca(OH2), how many grams of CaCO3, if it is 95% yield.

Ca(OH)2+CO2 ---> CaCO3 + H20

1) What does it mean by 95% yield? When doing % yield questions, it's usually the other way around - i.e. "what is the % yield). So i'm confused on how to approach this problem backwards?

1) Figure out how many mols of Ca(OH)2 you have based on 10 grams using the MW
2) Stoichiometry shows its a simple 1:1 ratio between Ca(OH)2 and CaCO3 so mol Ca(OH)2 = mol CaCO3
3) But, you only get 95% of the theoretical yield so multiply mol CaCO3 by .95 to get actual mol of CaCO3
4) Using MW, convert to grams of CaCO3

It's straight forward, just get around the 95% yield part of it... which is just saying if you would expect 100 mol from the reaction, you'd only get 95..

 

[californiamed]

wow thanks, you're awesome!