Dissolved 0.7500 g calcium chloride dihydrate and impure, in distilled water and the volume was elevated to 200.00 mL in a volumetric flask. A rate of 10.00 mL of the same consumed the titration 18.9 mL 0.0125 M EDTA using CALCON as indicator. What is the purity of the salt (% w/w)
1 mole EDTA reacts with 1 mol CaCl2.2H2O.
mols EDTA = M x L = 0.0125 x 0.0189 = approx 0.00024 but you need a better answer to that as well all of the steps that follow. They are estimates also.
This was in 10 mL aliquot from 200 mL total; therefore 0.00024 x (200/10) = approx 0.0045 mols CaCl2.2H2O in 0.75 g sample. Convert mols CaCl2.2H2O to grams CaCl2.2H2O, then
% purity = (g CaCl2.2H2O/g sample)*100 = ?
To determine the purity of the calcium chloride dihydrate salt, we need to calculate the amount of calcium chloride present in the impure sample. Here's how you can do it step by step:
1. Calculate the number of moles of EDTA used in the titration:
Moles of EDTA = Volume of EDTA (L) × Molarity of EDTA (mol/L)
Moles of EDTA = 0.0189 L × 0.0125 mol/L
2. Since calcium chloride (CaCl2) reacts in a 1:1 ratio with EDTA, the number of moles of calcium chloride is the same as the moles of EDTA.
3. Calculate the amount of calcium chloride in the sample:
Mass of calcium chloride (g) = Moles of calcium chloride × molar mass of calcium chloride
The molar mass of CaCl2 is 40.08 g/mol.
4. Calculate the purity of the salt:
Purity (% w/w) = (Mass of calcium chloride in the sample / Sample mass) × 100
To determine the sample mass, we need to calculate the concentration of calcium chloride in the impure sample.
5. Calculate the concentration of calcium chloride:
Concentration (mol/L) = Moles of calcium chloride / Total volume of sample (L)
The total volume of the sample is 0.2000 L.
6. Calculate the mass of calcium chloride in the sample:
Mass of calcium chloride (g) = Concentration (mol/L) × molar mass of calcium chloride × Sample volume (L)
The sample volume is 0.0100 L (10.00 mL = 0.0100 L).
Now, you can substitute the values obtained into the purity formula to find the purity of the salt.