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Zorluk: KolayPercentage Composition and Percentage Purity Calculations

Calculate the percentage by mass of calcium in a pure sample of calcium carbonate (CaCO3\text{CaCO}_3). [Ca=40,C=12,O=16][\text{Ca} = 40, \text{C} = 12, \text{O} = 16]

Cevap: 40 %

Cevap

The percentage by mass of calcium in calcium carbonate is 40%.
The molar mass of calcium carbonate (CaCO3\text{CaCO}_3) is 100 g/mol100\text{ g/mol}. Since one formula unit contains 40 g40\text{ g} of calcium, the percentage composition by mass of calcium is 40100×100%=40%\frac{40}{100} \times 100\% = 40\%.

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1
Calculate the molar mass of calcium carbonate (CaCO3\text{CaCO}_3).
Molar mass = 40+12+(3×16)=100 g/mol40 + 12 + (3 \times 16) = 100\text{ g/mol}.
Sum the relative atomic masses of all constituent atoms in one formula unit of CaCO3\text{CaCO}_3.
2
Determine the mass contribution of calcium in one mole of CaCO3\text{CaCO}_3.
Mass of Ca = 40 g40\text{ g}.
Each formula unit of CaCO3\text{CaCO}_3 contains 1 atom of calcium.
3
Calculate the percentage composition of calcium.
Percentage of Ca = 40100×100%=40%\frac{40}{100} \times 100\% = 40\%.
Divide the mass of calcium by the total molar mass of the compound and multiply by 100.

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Percentage composition of an element in a compound
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Percentage Composition and Percentage Purity Calculations

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