Chemistry
posted by LaurenPLEASE HELP on .
Analysis of Tap water (Hardness)
Was analyzed by a complexometric titraion by the following equations 1 & 2
1. Ca^2+ + Mg^2+ > Ca^2+ + Mg(Indicator)
2. Mg(Indicator) + Ca^2+ + EDTA^4 > CaEDTA^2 + MgEDTA^2 + free indicator
For the volume of titrant used (9.95 mL) calculate the:
a) Ca^2+ + Mg^2+ in sample (mol)
b)[Ca^2+] + [Mg^2+] of sample (M)
PLEASE HELP! I am very confused with this question and any guidance would be greatly appreciated!!!

I am confused by the question also. Is this a problem to be solved or is it a procedure that you have summarized with the two equations? I may be able to help if I know the procedure followed. The complexometric titration with EDTA is usually straight forward.

The equations 1 & 2 were given, and I believe we are supposed to make an equation for the reaction from this i.e. add them so that:
Ca^2+ + Mg^2+ + EDTA > MgEDTS^2 + CaEDTA
So by using the given volume of titrant (EDTA=9.95 mL) we could find the mol of Ca and Mg...i'm just not sure how to go about doing this (the stoichiometry is confusing me since the concentration they are looking for is Ca and Mg added...)