Lesson 2. Concentration of Ionic Solutions

Solubility 

Solubility is the amount of a solute that dissolves in a given volume of solvent. It is usually recorded in g/100 mL. 
How Temperature affects Solubility: 

• Solubility of solids in liquids increases with temperature
• Solubility of liquids in liquid is unaffected by temperature
• Solubility of gases in liquids decreases with temperature

How Solubility affects Solubility:

• Solubility of gases in liquids increases as the pressure of the gas above the solution increases 
• Solubility of solids in liquids is unaffected by a change in pressure

Substances that mix completely with each other in all proportions are said to be miscible. Miscibility depends on the nature of the solute and solvent. In general, polar solutes dissolve well in polar solvents, non-polar solutes dissolve well in nonpolar solvents. Probably you've heard the phrase  'Like dissolves like' before. 

There are exceptions to the 'like dissolves like' rule as some ionic compounds are either insoluble in water or only slightly soluble. The solubility table is used to predict the solubility of an ionic compound in water. Examine the solubility table in the back of your textbook, then watch the video below. 

Saturated Solutions
A saturated solution is a solution that contains both dissolved solute and undissolved solute. It is a solution said to have its maximum concentration of solute dissolved at a given temperature. Dissolving has not stopped in the solution because the solution is at equilibrium. The same amount of solute remains undissolved as solute continues to dissolve and crystalize out at the same rate. This is one type of dynamic equilibrium. At dynamic equilibrium reaction is two-directional. Example: 
The solubility of a solute is best determined when it is a saturated solution.