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Posted by winter897 (U15069247) on Friday, 16th November 2012
Hey guys, I was wondering how you calculate the theoretical yield (the maximum amount of product possible) for a question about percentage yield? like I can calculate the other part (amount of product collect) but don't know how to go about the theoretical yield.
Here's a question that I'm struggling on also: a student made 4.4g of calcium oxide from 4.0g of calcium. Calculate the percentage yield.
Thank you for your help!
Posted by The Bitesize Science Teacher (U14392404) on Saturday, 17th November 2012
Write the balance equation:
2Ca + O2 --> 2CaO
Work out the Ar and Mr values for the substances in the question:
Ar of Ca = 40
Mr of CaO = 40 + 16 = 56
Multiply by any number that appears in front of the formula in the equation:
Ca = 2 x 40 = 80
Mr = 2 x 56 = 112
Maximum yield of CaO from 4.0 g Ca = 4.0 / 80 x 112 = 5.6 g
Percentage yield = actual yield / maximum yield x 100
Percentage yield = 4.4 / 5.6 x 100 = 78.6%
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