SS Adding Mg EDTA Solution to Water Before Titration Question
Post-Laboratory Question: Please show all your calculations. Answers without calculation willnot be given any credit.
1. What is the purpose of adding the Mg-EDTA solution to the water sample before titrating
with EDTA ? ( 2 pts)
2. What is the purpose of adding KCN to the water sample for the titration with EDTA? (2
pts)
3. Consider the possibility that the EDTA salt that is used to prepare the 0.0100 M EDTA
solution in this experiment was not as dry as it should have been. (1 pt each)
a.
Would the concentration of EDTA be higher or lower than the actual value?
Explain your answer. Answers without explanation will not be given any credit.
a. The determined calcium ion concentration in the unknown would be higher or
lower than the actual value? (2 pts) Explain your answer. Answers without
explanation will not be given any credit.
4.
A 0.4505 g sample of CaCO3 was dissolved in HCl and the resulting solution diluted to
250.0 mL in a volumetric flask. A 25.00 mL aliquot of the solution required 26.25 mL of
EDTA solution for titration to the Eriochrom Black T end point.
What is the molar concentration of the EDTA solution? (4 pts)
