What is a precipitation reaction

sunny
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Registration date: 07/08/2004
Posts: 734
Place of residence: Hamburg
Posted: May 30, 2005 9:25 PM Subject:

ok, I'll give it a try.

So you know, there are substances that dissolve in water and there are substances that do not dissolve in water because they are sparingly soluble.

A precipitation reaction is e.g. the detection of chloride with silver nitrate.

So let's say you have a glass of water with table salt in it. Table salt is water-soluble. So there are Cl ions in the solution.

We need a silver nitrate solution to prove it. Silver nitrate is also soluble in water and the solution contains Ag +, among other things.

If you now put these two solutions together, Cl- and Ag + also come together. Together they make AgCl, silver chloride, and that is sparingly soluble. Therefore AgCl will turn out to you as a white precipitate. It arises as soon as you put both solutions together.

In the solution, which was previously transparent, you will then see something white that will settle on the floor after a while.
The precipitate is a solid that you could filter off.
The remaining ions are still dissolved.

The reaction equation is:



So you see AgCl combine and fail. The sodium ion and nitrate ion remain in solution because sodium nitrate is soluble in water.