March 28, 2024, 09:19:58 AM
Forum Rules: Read This Before Posting


Topic: Identify Calcium ion from magnesium ion  (Read 2379 times)

0 Members and 1 Guest are viewing this topic.

Offline Amber Chang

  • New Member
  • **
  • Posts: 4
  • Mole Snacks: +0/-0
Identify Calcium ion from magnesium ion
« on: January 14, 2015, 09:30:58 AM »
Hi, guys,
I want to know how to identify the Calcium ion from a solution which contains both of Calcium ion and Magnesium ion.
I try to use the USP method to identify the Calcium. However, I am afraid the Magnesium salts are also precipitated.

USP method is as follows.
Calcium—Solutions of calcium salts form insoluble oxalates when treated as follows. To a solution of the calcium salt (1 in
20) add 2 drops of methyl red TS, and neutralize with 6 N ammonium hydroxide. Add 3 N hydrochloric acid, dropwise, until
the solution is acid to the indicator. Upon the addition of ammonium oxalate TS, a white precipitate is formed.


Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27637
  • Mole Snacks: +1799/-410
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Identify Calcium ion from magnesium ion
« Reply #1 on: January 14, 2015, 12:46:51 PM »
EDTA in pH high enough to precipitate Mg(OH)2.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline Zyklonb

  • Full Member
  • ****
  • Posts: 104
  • Mole Snacks: +30/-10
  • Gender: Male
Re: Identify Calcium ion from magnesium ion
« Reply #2 on: January 14, 2015, 10:19:34 PM »
Magnesium sulfate is soluble, calcium sulfate isn't.

Offline kriggy

  • Chemist
  • Sr. Member
  • *
  • Posts: 1519
  • Mole Snacks: +135/-16
Re: Identify Calcium ion from magnesium ion
« Reply #3 on: January 15, 2015, 11:59:08 AM »
Do chelatometric titration:
1st titrate with chelaton III using eriochrome black T in buffered solution (we used 5ml of schwarzenbach buffer) to determine total concentration of Ca and Mg and then titrate with chelaton III using murexide in basic solution (added 5 ml NaOH) to determine amount of Ca.

Sponsored Links