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calculate the percentage composition of 'Ca','Co3','O2'in lime stone?

CaCO3 is the formula of the substance (calcium carbonate), which gives the information about the proportions of the different elements which make up the compound. To find the 'mass percentage' however, it is necessary to use the molar mass of each element.

Molar mass of Calcium = 40.08 g/mol
Molar mass of Carbon = 12.01 g/mol
Molar mass of Oxygen = 16.00 g/mol

To find the percentage mass of one of these elements, divide the molar mass of the element by the total molar mass of the compound (add them all up, using oxygen three times), then multiply by 100%.

Molar mass of CaCO3 = 40.08 +12.01 + 3*16.00 = 100.09 g/mol

% Calcium = 40.08/100.09 * 100% = 40.0%
% Carbon = 12.01/100.09 * 100% = 12.0%
% Oxygen = (3*16.00)/10.09 * 100% = 48.0%


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