Testing for nitrogen

Equipment

2 beakers (100 ml), 2 watch glasses, spatula, dropper pipettes, Bunsen burner to cover the beaker.

Chemicals

Ammonia water (C), ammonium chloride (Xi), sodium hydroxide (C), red litmus paper, or universal indicator paper.

How-to

Put on protective goggles. Do not smell the gases directly!

1 Analysis of liquid ammonia solution

A few ml of ammonia water are added to the beaker. Then a piece of damp indicator paper is glued to the convex underside of the watch glass. We then put the watch glass on the beaker.

2 Investigation of ammonium salts

A sample of ammonium chloride is placed in the beaker. To this, we add a small amount of solid sodium hydroxide. Then we proceed as above.

3 Investigation of organic nitrogen compounds

A sample of the substance to be examined (e.g. amines, amino acids, acid amides, polyamides, alkaloids, proteins, etc.) is placed in the beaker. To this we again add sodium hydroxide and moisten the mixture. Then we proceed as above. However, we now have to heat the mixture to release the ammonia.

Result

The indicator paper turns blue at different speeds depending on the ammonia concentration.