What happens when you mix ammonium nitrate and water?

by Johan on 15 januari, 2013

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Mixing water with ammonium nitrate

Have you ever wondered what would happen if you mix ammonium nitrate and water? The answer may actually surprise you since the answer is commonly observed in households. Ammonium nitrate and water when combined produces an endothermic reaction. When we are speaking about thermodynamics, the term endothermic is a type of reaction wherein the process actually absorbs the energy found in its immediate surroundings but in the form of heat. This is the reason why people associate it with the feeling of coldness since the heat is actually absorbed. If you look at the process closely, there are two main reactions that actually occur. When the polar molecules of the water separate the nitrate ion from the ammonium ion, this produces an endothermic reaction. Heat is being absorbed so the person may feel cold. But when the ions that have been separated are now suspended in the remaining water in the solution, they become hydrated and this process produces an exothermic reaction. An exothermic reaction produces heat since it gives off energy. But in physics, it requires more energy to actually separate the ammonium and nitrate ion than the hydration of the ions, so the only reaction that is physically felt is the endothermic one.

Ammonium nitrate and water chemical equation

The chemical equation for ammonium nitrate and water combination is NH4NO3 ? NH4 + NH3. This process is used widely in instant cold pack devices. If you dissect a cold pack open, you will be able to see that there is a separate compartment that holds a bag of water and an inner compartment for ammonium nitrate. The aim of these compartments is to prevent the two from mixing together. Once a cold pack is needed, a person would need to squeeze the pack. Squeezing the pack will make the inner compartment break, making ammonium nitrate and water combine together. When the phenomenon occurs, the process produces an endothermic reaction. Water will break down ammonium and nitrate ions and energy will be absorbed. The cold pack will eventually start to cool and will stay cold for approximately an hour.

Experimenting with ammonium nitrate and water

A lot of science experiments can be made to check the reaction between ammonium nitrate and water. The materials are actually very easy to obtain and does not cost a lot. You simply need some ammonium nitrate and water to complete the project. Once the experiment is done, you can actually pour the mixture to any soil and it will still serve its purpose as a fertilizer. Since water is a polar substance, it can dissolve ionic crystals and salts. Ammonium nitrate is a salt, thus, it easily dissolves in water. The unique thing about this experiment is the fact that water is actually not part of the chemical equation. Water will stay as is and so are the ions of ammonium nitrate. But when the water with dissolved ammonium nitrate is heated, another product is formed which is laughing gas or nitrous oxide. Ammonium nitrate and water combination is actually helpful especially in its use in cold packs.

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