EDTA ( ethylenediaminetetraacetic acid) is a " chleating agent" that can bond with entities like Ca2+ forming complex ions.

 

Calcium and magnesium ions are the cheif causes of water hardness. EDTA molecules bind hard-water ions , removing them from solution. A common indicator used in EDTA titrations is eriochrome black T (EBT), which changes from pink to blue at a single endpoint, when all calcium and magnesium ions have reacted with EDTA. EDTA titrations are preformed at a pH of 10.

 

I will determine the concentration of calcium ions through titration.

After this titration i will alter the sample and i must plan and write a procedure for modifying the concentration of calcium ions in my sample.

 

I would like to know what other methode i could use to alter the calcium ion concentration other than by diluting with distilled water.

 

Thank you very much for your help.

Uhhhh I think one post on this question is enough.

 

This thread should be closed.

EDTA ( ethylenediaminetetraacetic acid) is a " chleating agent" that can bond with entities like Ca2+ forming complex ions.

 

Calcium and magnesium ions are the cheif causes of water hardness. EDTA molecules bind hard-water ions ' date=' removing them from solution. A common indicator used in EDTA titrations is eriochrome black T (EBT), which changes from pink to blue at a single endpoint, when all calcium and magnesium ions have reacted with EDTA. EDTA titrations are preformed at a pH of 10.

 

I will determine the concentration of calcium ions through titration.

After this titration i will alter the sample and i must plan and write a procedure for modifying the concentration of calcium ions in my sample.

 

I would like to know what other methode i could use to alter the calcium ion concentration other than by diluting with distilled water.

 

Thank you very much for your help.[/quote']

Do I understand this question?

Changing the calcium ion concentration can be done in many very trivial ways. E.g. add some known amount of a solution of CaCl2 and mix this with the liquid. You can also use a solution of Ca(OH)2 if you want to maintain high pH.

Milk will also do the job .

 

But... I have the feeling that these are not the answers you expect. They seem too trivial to me. Am I missing something?

Unfortunatly i dont exactly know myself. My teacher directed me in the way of hard water and methodes of reducing the amounts of calcium and magensium in the water. Although i am finding this to be a little too complicated for a school assignment

just use edta or other chalting agents to the water. something similar to "cl through tincture" perhaps.

Unfortunatly i dont exactly know myself. My teacher directed me in the way of hard water and methodes of reducing the amounts of calcium and magensium in the water. Although i am finding this to be a little too complicated for a school assignment

A well known method for reducing the amount of free Mg(2+) and Ca(2+) ions is the addition of a small amount of calgon. Calgon, a.k.a. sodium hexametaphosphate, coordinates to the calcium and magnesium ions. The ions are not removed, but they are not free anymore. Per example, they cannot form a precipitate with soap or detergents anymore and their adverse effect is reduced effectively

 

It might be interesting to do the EDTA titration with plain tap water and with tap water, in which is pinch of calgon is dissolved. I would suggest you discuss this with your teacher.

 

Yet another technique for reducing impurities in water is by means of certain membranes or filters. These membranes are constructed, such that water molecules can go through them, but the calcium ions not. However, for more details on this, please go to a library, because I cannot give you any sound advice on this.