[dpascali]

Part1: A 0.5215-g sample of CaCO3 is dissolved in 12M HCl and the resulting solution is diluted to 250.0mL in a volumetric flask.
There is a second part to this problem that has also taken me many hours to figure out how to set up.
the set up is:
25.00 mL aliquots of the solution from problem 1 are titrated with EDTA to the Eriochrome Black T end point. A blank containing a small measured amount of Mg 2+ requires 2.60 mL of the EDTA to reach the end point. An alquot to which the same amount of Mg 2+ is added requires 28.55mL of the EDTA to reach the end point.
the questions are:
a.) how many mL of EDTA are needed to titrate the Ca 2+ ion in the aliquot?
would you just add the 25.00mL and 28.55mL then subtract the 2.60 mL from that answer to get the total?
b.) how many moles of EDTA are there in the volume obtained from Part a?
and obviously i need to figure out a. to get to b.

[forislam20]

here u are
A]
1)the no of moles of cacl2 formed in the dissolution reaction can be obtained from the quotient of the weight of caco3 &its molecular weight
2)on diluting the solution to 250ml u can notice that the no of moles of cacl2 will remain the same
3)but on taking 25 ml the no of moles of cacl2is equal to (25*the original no of moles)/250
4)if u have the molarity of edta solution u can calculate the volume needed using the role:M*V=M*V

[forislam20]

B]THEN USING THE VOLUME OBTAINED IN PART A
if uscaned the problem and sent me as it is i can give u adetailed answer
try to contact me