Hello, we recently did a lab in our chemistry class to analyze an Unknown amount Calcium Carbonate which was titrated with EDTA.
Our titration results were:
mass of the unknown CaCO3 was 0.172 g and the mL of EDTA added was 30.7. How do I find the percent mass of Ca?
also, the Molarity of EDTA was determined to be .0404
moles EDTA = M x L = 0.0404 x 0.0307
moles Ca = moles EDTA
mass Ca = moles Ca x atomic mass Ca.
%Ca = (g Ca/mass sample)*100 = ??
To find the percent mass of calcium in calcium carbonate (CaCO3), you'll need to calculate the amount of calcium present in the sample and then express it as a percentage of the mass of the entire sample.
To do this, follow these steps:
1. Determine the molar mass of CaCO3:
- The molar mass of calcium (Ca) is 40.08 g/mol.
- The molar mass of carbon (C) is 12.01 g/mol.
- The molar mass of oxygen (O) is 16.00 g/mol.
- So, the molar mass of CaCO3 is (40.08 + 12.01 + (3 * 16.00)) = 100.09 g/mol.
2. Calculate the number of moles of CaCO3:
- Moles = Mass / Molar mass
- Moles of CaCO3 = 0.172 g / 100.09 g/mol = 0.0017196 mol
3. Determine the stoichiometry of CaCO3 and Ca:
- In the chemical formula of CaCO3, there is one mole of calcium (Ca) for every mole of CaCO3.
- So, the number of moles of Ca is also 0.0017196 mol.
4. Determine the mass of calcium:
- Mass of Ca = Moles of Ca * Molar mass of Ca
- Mass of Ca = 0.0017196 mol * 40.08 g/mol = 0.06899 g
5. Calculate the percent mass of calcium:
- Percent mass = (Mass of Ca / Mass of CaCO3) * 100
- Percent mass of Ca = (0.06899 g / 0.172 g) * 100 = 40.11%
Therefore, the percent mass of calcium in the unknown calcium carbonate sample is approximately 40.11%.