Question

Calculate the percentage of pure aluminum in 5kg of aluminium oxide [Al2O3] of 90% purity .[ Al=27,O=16]

Answer 1

Al2O3= 27*2+16*3=54+48=102g.

102g Al2O3 contains                        54g of pure Al

5000g Al2O3 contains                       ?

(54*5000)/102 =270000g or 270kg

90% of pure Al2O3 =     (270 x 90)/100=  243 %