percentage composition.

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Question: 

(b)       calculate the percentage composition of each of the following compounds.

            (i) MgSO4      

                        Formula mass of MgSO4 = 24 x 1 + 32 x1 + 16 x 4 = 24+ 32 + 64= 120 amu

                        %age of Mg = 24/120 x 100 = 20%

                        % age of S = 32/ 120 x 100 = 26.7%

                        %ae of O = 64/120 x 100 = 53.3 %

            (ii) C3H6O

                        Molecular weight of C3H6O= 12 x3 + 1x 6 + 16 x 1= 36 + 6 + 16 = 58 amu

                        %age of C is= 36/58x 100 = 62.02%

                        %age of H is= 6/58 x 100 = 10.34 %

                        %age of O is= 16/58 x 100= 27.6 %

 

            (iii) KMnO4

                        Formula mass of KMnO4 = 39x1 + 55 x1+ 16 x 4 = 39+ 55+ 64=158 amu

                        %age of K is= 39/158 x 100= 24.68%      

                        %age of Mn is = 55/158X100= 34.8%

                        %age of O is = 64/158X 100 = 40.5%

            (iv)       C6H6  

                        Molecular weight of C6H6 = 12x6 +1x6= 72 + 6 = 78 g/mol

                        %age of C is= 72/78X100 = 92.3%

                        %age of H = 6/78 X 100 = 7.69% 

(i)            Al2(SO4)

Formula weight of Al2(SO4)3 = 27X2 + 32X3 + 16X12

s                                                    54 +   96   +  192  =  342g/mol

%age of Al = 54/342 X 100 = 15.8%

%age of S = 96/342 X 100 = 28.1%

%age of O = 192/342 X 100 = 56.1%

                       

(ii)          CaCO3          

Formula weight of CaCO3 = 40X1 + 12 X 1 + 16 x 3 = 40+12+48= 100 g/mol

%age of Ca = 40/100X 100 = 40%

%age of C = 12/ 100X 100 = 12 %

%age of O = 48/100 X 100 = 48%

 

            (vii) CH4

                        Molecular weight of CH4 = 12x1 + 1x4 = 12 + 4= 16 g/ mol

                        %age of C = 12/16 X 100 = 75%

                        %age of H = 4/ 16 X 100 = 25%

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