Preparation of the Ca2+ standard solution
A 0.1104 g sample of primary standard grade CaCO3 (M.M. = 100.09) was transferred to a 100 mL beaker containing 50-mL distilled H2O. Concentrated HCl was added to the mixture until clear. The solution was transferred quantitatively to the 250-mL volumetric flask and diluted to the mark. Cover securely and mix the solution thoroughly.
1. The molarity of the Ca2+ ions in the standard solution is ________.
Standardization of a Solution
A 50-mL aliquot of the 0.04412 M Ca2+ standard solution was transferred into a conical flask. After adding 50 mL H2O, the mixture needed 20.62 mL EDTA solution to reach the endpoint.
2. Calculate the molar concentration of the EDTA solution. ________ M EDTA
3. Express the concentration of the EDTA solution in terms of mg Ca/mL.
Calculate the amount (mmoles) Ca in the 50-mL aliquot.
Convert the amount (mmoles) Ca to mass (mg) Ca (M.M. = 40.08)
Divide the mass (mg) Ca by the volume of EDTA solution.
The ratio (mg Ca/mL) is the concentration of the EDTA solution expressed as Ca titer of EDTA.
Analysis of Ca Supplement Drug
The composition of an OTC Ca Supplement is advertised as 325 mg calcium lactate, Ca(CH3CH(OH)CO2)2 per tablet.
List of Molar Mass: Ca(CH3CH(OH)CO2)2 = 218.24; Ca = 40.08
4. Calculate the number of mmoles of Ca present in 1 tablet. ________ mmol
5. How many mL of 0.0100 M EDTA solution will be needed to titrate a solution that contains 1 dissolved tablet of the Ca supplement drug? ________ mL
6. Would you recommend diluting the sample before titration? ________
Support your answer.