Transcript

NARRATOR

The chemical properties of nitrates vary according to the position of the metal in the reactivity series. Heating potassium nitrate produces the nitrite and oxygen. The standard test for oxygen is the relighting of a glowing splint.

Taking it a stage further, we can demonstrate the oxidising power of potassium nitrate by melting some, and adding a piece of charcoal. In this vigorous reaction, the gases evolved are carbon monoxide, carbon dioxide, and nitrogen. This is not too far removed from the chemistry of gunpowder, where charcoal and sulfur act as fuels, which are oxidised highly exothermically by potassium nitrate.

Heating lead nitrate is somewhat different. In this case, brown nitrogen dioxide and oxygen are formed.

This is silver nitrate which, on heating, again produces nitrogen dioxide and oxygen. But this time, because silver oxide is unstable, we form silver metal, which you can see on the side of the tube. Let's now take a look at ammonium nitrate.

If we heat it gently, we produce dinitrogen monoxide, as the solid melts. Like oxygen, dinitrogen monoxide will rekindle a glowing splint. In fact, it just about succeeds but perhaps there's too much water vapour around.