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I'd really appreciate it if someone could fully explain to me the following question, 

 

Calcium Carbonate decomposes on heating as shown below:

 

CaCO3 --> CaO + CO2

 

When 50g of calcium carbonate are decomposed, 7g of calcium oxide are formed. What is the percentage yield of calcium oxide?

 

Thanks!

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Okay so it goes like this.

 

First let me list out all the molar masses for the different compounds in the reaction: Mr(CaCO3) = 100g/mol; Mr(CaO) = 56g/mol; Mr(CO2) = 44g/mol

 

Now, using the initial mass of CaCO3 and the balanced equation you can work out the theoretical yield of CaO that would generally be expected to be produced.

 

So (Number of moles of CaCO3 = 50/100 = 0.5 moles). Now since the ratio of the reagents are 1:1:1, 0.5 moles of CaO would also be expected to be produced (the theoretical yield)

 

Now divide the number of moles of CaO that was actually produced by the theoretical yield and multiply by hundred to calculate the percentage yield.

 

Working:

 

7/56 = 0.125 

 

Percentage Yield = (0.125 / 0.5) x 100

 

Hope that helped. Cheers! 

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