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Percentage yield...

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  • Message 1. 

    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! smiley - smiley

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  • Message 2

    , in reply to message 1.

    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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