Answer:
2) 25.0mL aliquots of the solution in problem 1 are titrated with EDTA to the calmagite end point. A blank containing a small measured amount of Mg2+ requires 2.12mL of the EDTA to reach the end point. An aliquot to which the same amount of Mg2+ is added requires 25.88mL of the EDTA to reach the end point.
a. How many mL of EDTA are needed to titrate the Ca2+ ion in the aliquot?
b. How many moles of EDTA are there in the volume obtained in a.?
c. What is the molarity of the EDTA solution?
Explanation:
Given that;
Volume of aliquot = 25mL
Blank reading = 2.12mL
2a)
Volume of EDTA used for Ca²⁺ ion
25.88mL - 2.12mL = 23.76mL
Therefore mL of EDTA needed to titrate the Ca²⁺ ion in the aliquot is 23.76mL
2b)
Molarity of Ca²⁺ ion is 0.0172M
Mole of EDTA =
[tex]=\frac{0.0172 moles}{1l} \times (25mL) \times \frac{1L}{1000mL} \\\\=0.00043moles[/tex]
2c)
Molarity of EDTA = mole of EDTA / Vol. of EDTA
[tex]=(\frac{0.00043mole}{23.76mL} )\times \frac{1000mL}{1L} \\\\=0.0180M[/tex]
