Potassium nitrate is a crystalline salt with the molecular formula KNO3, and an alkali metal nitrate -- it's an ionic salt of potassium ions K+ and nitrate ions NO3−. Laboratories often use Potassium nitrate as a reagent in lab experiments because it reacts with many different compounds. For example, it reacts readily with sugar, acids and sulfur.
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You can carry out potassium nitrate reaction experiments with many compounds, including acids, sugar and sulfur. Some potassium nitrate experiments involve handling concentrated acids and toxic vapors, so they should be supervised in a lab with all necessary safety precautions.
Potassium Nitrate and Sugar
A nitrate is a strong oxidizing agent because it is a source of oxygen. A good example of this is adding potassium nitrate to table sugar. Mix a small amount of potassium with the sugar and place it on a non-combustible surface. When you ignite the nitrate, the sugar burns quickly. This is part of the reaction that occurs in July 4th sparklers, a combination of potassium nitrate, sugar and metal filings. The reaction of sugar and nitrate makes heat, which oxidizes the metal filings and gives out light. This is also the main reaction in sugar rocket fuel. The nitrate and sugar solids react to create carbon dioxide and water gases, which provides the power needed to launch the rocket. Conduct this experiment in a lab with supervision and all necessary safety precautions to ensure a hazard-free experiment.
Potassium Nitrate and Sulfuric Acid
Potassium nitrate reacts with hydrochloric acid to make nitric acid. Add concentrated sulfuric acid to dry potassium nitrate, then melt the mixture over heat to distill the nitric acid. Because preparing nitric acid involves handling concentrated acids and toxic vapors, this experiment is not recommended for amateur chemists and best observed in a lab with all necessary safety precautions.
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Potassium Nitrate, Sulfur and Charcoal
The earliest known chemical explosive is gunpowder, also known as black powder, which is made by combining potassium nitrate, sulfur and charcoal. Each ingredient must be in ground form, and the ratio should be 75 parts potassium nitrate, 15 parts charcoal and 10 parts sulfur. Boil the potassium nitrate until it has completely dissolved, then add the charcoal and sulfur. Add this mixture to isopropyl alcohol and stir. Chill, filter and lay the mixture out to dry, then run it through a sieve to break it up. The potassium nitrate is an oxidizer and the sulfur and charcoal act as fuels, creating a huge amount of heat and gas volume. Carry out this experiment in a lab with supervision and all necessary safety precautions.