SOLUTIONS

9.2 - Terminology

Soluble/Insoluble

• sugar is soluble in water - this means that you can dissolve a large quantity of sugar into water. How much is " a large quantity"?
  
  In science, we use the term solubility to quantify the amount of solid solute will dissolve in a given quantity of solvent at a specific temperature.
  

  -	The solubility of sodium chloride, table salt, is 36 grams per 100 grams of water at 20oC.

  
  
• when a substance does not dissolve in a solvent, it is insoluble. Click on the and view the solubility rules. Many compounds such as AgCl, Hg₂Cl₂, PbCl₂, BaSO₄, SrSO₄, PbSO₄ are insoluble in water. You should become familiar with the compounds that are listed on the table of the solubility rules and be able to recognize the types of compounds that are soluble or insoluble in water.

Miscible/Immiscible

• Miscible and immiscible describes what happens when two liquids are brought in contact with each other. In section 1.8, we learned that liquids such as gasoline, water and mercury are immiscible. The three liquids separates into three distinct layers, with the liquid that is the most dense on the bottom. Liquids such as water and ethyl alcohol are miscible. This means that the two liquids dissolves in one another and there are no separation of layers observed.
  

Saturated/Unsaturated

• When a solution contains as much dissolved solute as it can hold at a given temperature and has undissolved solute in the solution, the solution is said to be a saturated solution.
  

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  The solubility of sodium chloride, table salt, is 36 grams per 100 grams of water at 20oC. When we place 40 grams of table salt in 100 grams of water at 20oC, 36 grams will become dissolved in water. The remaining undissolved crystal will remain as a solid in the solution. This is a saturated solution. However, solubility increases with temperature. This means that at higher temperature, the solubility of table salt is greater than 36 grams in 100 grams. If we increase the temperature to 30oC, the remaining 4 grams of undissolved table salt crystal will dissolve into the solution. At 30oC, this solution contains less solute than the solubility limit. Therefore, at 30oC, this solution becomes unsaturated.

Section 14.1
Solutions ..p363
Section 14.2
Types of Solutions ..p363

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