What is Salt peter or Potassium Nitrate?

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Saltpetre or Saltpeter is chemically known as Potassium nitrate. It is a white crystalline powder that is soluble in water and is not combustible but aids in combustion of materials which can lead to explosions under prolonged heat conditions leading to toxic fumes. Potassium nitrate has many wide applications ranging from fireworks, rocket propellants, explosives to fertilizers and as a food preservative. Now as to what makes it good as a fertilizer is the high nitrogen content this compound has which is one of the necessary nutrients for plant growth. Both potassium nitrate and nitrite are used as preservatives which most of you might know if you look at the contents on your deli meats and lunchables in the grocery section. Its explosive property makes it the main ingredient in gunpowder and hence finds its application in mining as well.

What are the Physical properties of Potassium nitrate?

Potassium Nitrate is a very strong oxidizing agent which means it will readily give away electrons and thus reacts explosively with reducing agents such as

• Molecular Formula : KNO3
• Molecular Weight : 101.11 
• Melting point : 633.3º F
• Boiling Point : 752 º F at 760.0 mm Hg
• Water Solubility : Slightly soluble in water and increases with temperature

What are the Chemical Reactions of Potassium Nitrate?

Potassium nitrate is formed by the reaction between potassium chloride and sodium nitrate

• KCL + NaNO3 -------->KNO3 + NaCl

Oxidizing reaction of Potassium Nitrate: Decomposes to potassium oxide, nitrogen gas and oxygen : 

• 2KNO3  +  Heat  --------> 2K₂O + N₂ + O₂ When heated to temperatures above 560º C KNO3 will decompose to potassium nitirite and oxygen.
• KNO3 + H2O -------------->KOH + HNO3

What is Rcandy?

Rcandy is a technique to make propellant without melting the components, potassium nitrate and Sugar. These two compounds are dissolved and recrystallized to form the propellant which is actually moldable. Potassium nitrate is highly hygroscopic and hence should be stored in an aritight container otherwise  it will be useless. The propellant is nontoxic but KNO3 can cause cancer so it should not ingested.

What are the Sources of Potassium nitrate (Salt petre)?

The three main sources of Potassium nitrate are : 

1. Nitrate beds which naturally occur in nature due to the continuous decomposition of organic matter. This occurs naturally in rocks in countries such as India and Egypt.
2. The second source is through manmade nitrate beds. This method was practiced early on in European countries such as Sweden.The process involved putrefying organic matter in beds which was combined with porous earth and wood ashes which had calcium carbonate. This was moistened with the drainage from stables which was mostly liquid and was allowed to stand for months. The nitrifying bacteria decompose the matter impregnating it with nitrates of potassium, calcium and magnesium. On leaching the nitrates go into the solution. This solution is boiled with wood ash which precipitates calcium and magnesium carbonates, potassium nitrate is obtained by concentrating remaining solution.
3. The third process is by the reaction of sodium nitrate with potassium chloride which forms potassium nitrate. This is a double decomposition reaction and is the most widely used for commercial production currently. 

What are the Uses of Potassium Nitrate?

Potassium Nitrate has numerous uses,

• Fertilizer: Commonly used as a fertilizer as it provides the plants with both vital nutrients, potassium and nitrogen.
• Oxidizer : As it is a good oxidizing agent it is use din gunpowder and fireworks. It is also used in cigarettes to ensure complete burning of the cigarettes.
• Preservative : Used  as a preservative in meats originally but currently has been replaced with sodium nitirite and nitrate which deters the growth of bacteria. 
• Other Uses : As a fireextinguisher,  since it reacts with the free radicals in the flame to form potassium carbonate, in removing trees stumps as it provides nitrogen in diseased trees which quickens the process of decaying. It is also used in tooth pastes as it seem to help with sensitive teeth. It was once used as a treatment for low blood pressure but not anymore.