We are asked to calculate the percent composition of CaSiO₃ which refers to the percent of the total mass of the compound that is made up of each element. We will calculate the percent by mass of each element in the species, so we will first find the molecular weight of CaSiO₃.
Ca = 40.1 g/mol
Si = 28.1 g/mol
O = 16.0 g/mol
The total molecular weight is as follows:
[(40.1 g/mol) x 1 mol Ca] + [28.1 g/mol x 1 mol Si] + [(16 g/mol) x 3 mol O] = 116.2 g/mol
Now that we have the total mass of CaSiO₃, we can calculate the percent composition in 1 mol of CaSiO₃:
% Ca = [(40.1 g/mol x 1 mol Ca)/116.2 g] x 100% = 34.5% Ca
% Si = [(28.1 g/mol x 1 mol Si)/116.2 g] x 100% = 24.2% Si
% O = [(16 g/mol x 3 mol O)/116.2 g] x 100% = 41.3% O
The percent composition of CaSiO₃ is found to be 34.5% Ca, 24.2% Si and 41.3% O.
