Purpose : Collect the experimental data necessary to construct a solubility curve for potassium nitrate (KNO3) in water.
Introduction : When it comes to solid materials , it can be classified according to their dissolution types – salt that are difficult to dissolve and salts that dissolve fast, in this case the main thing that affects the solubility is the temperature, or by the type of chemical bond connecting the solid molecules – ionic (eg salts) or covalent bond (eg organic materials).
Le Chatelier's principle : In chemical equilibrium, if a chemical equation undergoes a change in temperature, pressure or concentration, Balance will deviate to minimize the resulting change. For example : 1. If the concentration of the reactants will rise , it will try to minimize the change in balance and move towards the products . 2. In an Aksotrmit equation( heat is a product ), if the temperature exceed the system moves toward the reactants .Types of solutions : When we have a solvent and a dissolved in a solution, and the dissolved not yet dissolve in the whole solution , the solution is unsaturated . When the solution comes to a maximum concentration, which means that dissolved cannot be dissolve in the solution anymore, the solution is saturated.  When any material that we will add to the solution sink, the solution will be supersaturated.
There are two factors that affect the ability of dissolving for solids :
1.The anthropic factor : This is a measure of disorder . In entropy, the molecules are in maximum disarray. The natural tendency of all solid is to dissolve in water, becuase this act increases the entropy .
2. The energy factor : Every chemical action require a certain amount of energy. When solid Dissolves, we have 2 types energy-  • Separation Energy E1 : Between the solid molecules there are Intermolecular and electric bonds, in order to dissolve the solid we must invest energy to overcome these connections , this energy is the Separation energy.
This energy is "against" the process of dissolution, and is absorbed in the process. ….