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Chemistry Calculations

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1. 10. Copper (II) Oxide reacts with sulphuric acid to produce Copper (II) Sulphate. If this is allowed to crystallise the formula of the crystals is CuSO4 X 5H2O. What mass of copper oxide would be needed to produce 100 g of crystals?

11. 10 g of Aluminium Oxide reacted with sulphuric acid and 27 g of aluminium sulphate was produced
a)Find the % yield of aluminium sulphate
b)Find the atom economy for this reaction where aluminium sulphate desired product

Could someone help my answer theses questions? Also, if you wouldn't mind, could you show your steps so I know how you got your answers. Thanks
2. Hello Debbie (or Rose!),

First you need a balanced chemical equation:

Then work out the molecular masses of each substance that you need to use/find weights of.

Copper sulphate crystals: CuSO4.5H2O has molecular mass: 63.5 (Cu) + 32 (S) + (16 X 4) (4 Os) + (2 X 5) (5H X 2) + (5 X 16)(5Os)= 95.5 + 64 +10 + 80 = 249.5

Q10. CuSO4 used to produce this 249.5 g of crystals is molecular mass of one CuSO4 (equation is balanced with just one of each reactant and one of each product) - this mass is Cu = 63.5 S = 32 and O4 = 16 X 4 = 64. TOTAL = 159.5.

So 249.5 g of crystals are given by 159.5g of CuSO4 (copper sulphate)

Therefore 100g of crystals are given by (159.5 X 100/249.5) grams of Copper sulphate = 63.93 gm

You use 100/249.5 AND NOT 249.5/100 because 100g of crystal will obviously need less copper sulphate thn 249.5 gm

You can do Q11 in same way - I will give you headway with the balanced equation:

Attachment 585956585962
Attachment 585956585962
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Updated: October 11, 2016
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