October 21, 2021, 08:56:26 AM
Forum Rules: Read This Before Posting


Topic: EDTA - Please, i still need *delete me*  (Read 17563 times)

0 Members and 1 Guest are viewing this topic.

dpascali

  • Guest
Re:EDTA - Determination of the hardness of water.
« Reply #15 on: January 23, 2006, 07:32:33 PM »
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.

dpascali

  • Guest
Re:EDTA - Determination of the hardness of water.
« Reply #16 on: January 23, 2006, 07:35:04 PM »
No. 0.00521 is not a concentration yet. It is number of moles.

I see...
so it would be... .02083 M x .025L= 5.20979x 10-4
« Last Edit: January 23, 2006, 07:58:07 PM by dpascali »

dpascali

  • Guest
Re:EDTA - Determination of the hardness of water.
« Reply #17 on: January 23, 2006, 07:44:00 PM »
Has my luck run out for help haha ;D ???
« Last Edit: January 23, 2006, 07:44:19 PM by dpascali »

dpascali

  • Guest
Re:EDTA - Determination of the hardness of water.
« Reply #18 on: January 23, 2006, 08:30:12 PM »
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.

Offline plu

  • Full Member
  • ****
  • Posts: 193
  • Mole Snacks: +15/-7
  • Gender: Male
Re:EDTA - Please, i still need *delete me*
« Reply #19 on: January 25, 2006, 04:45:02 PM »
You are thinking too complicated again!  You need 2.60 mL to titrate the Mg2+.  Now, you need 28.55 mL to titrate the Mg2+ and the Ca2+.  28.55 - 2.60 = 25.95 mL to titrate the Ca2+.

Offline anuvrutti3035

  • Very New Member
  • *
  • Posts: 1
  • Mole Snacks: +0/-0
Re: EDTA - Please, i still need *delete me*
« Reply #20 on: January 17, 2008, 08:00:34 AM »
so for b) how would you figure out the molarity of the EDTA to get the # of moles of EDTA? (jw could this be the same as the molarity of Ca2+ from 1b?)

Sponsored Links