What is silver nitrate with water

Experiment of the month
November 2009


Mineral water contains various dissolved ions, including chloride. This can be demonstrated by a simple precipitation reaction. It turns out that the chloride content can be very different.

Equipment and chemicals:
Test tubes, Pasteur pipettes
Mineral water, tap water
5% silver nitrate solution, 20% nitric acid.

Test tubes with demin. Fill water, various mineral waters and tap water approx. 2-3 cm high. Add 5 drops of 20% nitric acid and shake. Add 3 drops of silver nitrate solution to each test tube. Depending on the chloride content, different amounts of a white precipitate arise, the solution with demin. Water stays clear.

Silver ions and chloride ions result in a white precipitate of AgCl. The addition of acid prevents silver carbonate from precipitating. Most mineral waters contain between 5 ... 100 mg / l chloride, but there are also particularly salty and particularly low-salt mineral waters.
In the example shown, the glass contains (1) demineralized water, (2) - (5) mineral water with 5/7/16/110 mg / l chloride, (6) tap water.
In tap water, the chloride content is additionally increased by chlorination, which is often carried out for disinfection.

Nitric acid and silver nitrate are corrosive.

The solutions are added to the heavy metal waste.

Literature & Links:
P. Grob: Simple school experiments on food chemistry, experiment 8.4
Inorganic Chemistry Textbooks
Information center for German mineral water

October 2009: Tablet coatings



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Page created on: Saturday, October 31, 2009,A. Schunk,Charité - University Medicine Berlin.

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