Question

What happens when Potassium nitrate is heated?

Answer 1

As we know that Alkali metals react with nitrates and oxygen to produce metal nitrates and metal oxides. Potassium nitrate is an ionic salt which is composed of potassium ions and the nitrate ions which can be heated below or above the temperature of ${400^\circ }C$.

Complete answer:
As we are very well aware of the fact that when potassium nitrate which is a whitish grey chemical compound usually helps in manufacturing of fertilizers, sensitivity toothpastes etc. When potassium nitrate $(KN{O_3})$ is heated, a decomposition reaction takes place where molten potassium nitrite $(KN{O_2})$ is formed and dioxygen gas is released in the course of reaction. This reaction can either take place under mild temperature as well as strong temperature. We can show this reaction with the help of the following equation as:
$KN{O_3}(s)\xrightarrow{{above\;or\;below\;{{400}^\circ }C}}KN{O_2}(s) + {O_2}(g)$

Additional information: Potassium nitrate is produced when ammonium nitrate and potassium hydroxide combine in a chemical reaction and form ammonia gas, potassium nitrate and water molecules. It can also be produced by reacting ammonium nitrate with potassium chloride resulting in the formation of potassium nitrate and ammonium chloride.
Another method of production of potassium nitrate is by neutralising the nitric acid with potassium hydroxide. On industrial scale, potassium nitrate is produced by the double displacement reaction between potassium chloride and sodium nitrate compounds which results in the formation of sodium chloride and potassium nitrate.

Note: Remember that potassium nitrate is widely used as a source of nitrogen as well as nitrate. It is also used as an oxidiser in black-powder which is used in most of the explosives. Another name of potassium nitrate is saltpetre which is used as a thickening agent in food items like soups and stews. It decomposes to release oxygen gas which is used for other purposes.