The Solubility of Potassium Nitrate

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The Solubility of Potassium Nitrate

Aim

To investigate how the solubility of Potassium Nitrate is affected by

Temperature.

Background Knowledge

Potassium Nitrate (KNO3) is an ionic compound. The strong ionic bonds

hold the compound in an ionic lattice which gives KNO3 its crystalline

structure. These ionic bonds also have other properties which will

affect my investigation, I must be aware of these properties for

greater accuracy in my method. The ionic bonds give KNO3 high melting

and boiling temperatures. In the case of KNO3, ionic bonds are

present, which are strong and hard to break under room temperature; I

believe that this may have an impact on the solubility of KNO3 at low

temperatures, where there is very little energy present to break these

bonds.

Particles move faster and collide with a greater energy output. A

greater proportion of these particles now have enough energy to react.

Therefore there is a greater chance of a collision between KNO3 and

water molecules resulting in a successful reaction.

Hypothesis

My hypothesis is that the temperature of the water affects the

solubility of Potassium Nitrate. As I have already addressed this, as

you increase the temperature, you also increase the kinetic energy of

each particle; thus increasing the chance of a successful reaction.

This means more potassium nitrate will be broken down and dissolved in

the water as the temperature increases. I believe that the solubility

of the KNO3 will increase at a proportional rate to the increase in

the temperature of the water.

[IMAGE]When the KNO3 dissolves, it can be classed as a chemical

reaction. It follows therefore that in order for the KNO3 to dissolve,

an activation energy barrier must be overcome. Activation energy is

the energy required to kick-start a chemical reaction. If the

activation energy barrier is not reached (i.e. if the particles do not

have enough energy on collision to react) then the reaction will not

proceed and the KNO3 cannot dissolve in the water.

In order for KNO3 to be dissolved, it must come into contact with

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