Solutions

A.  How Solutions Form

1.  Types of solutions

a.  Gaseous solutions (air)

b.  Liquid solutions (sugar water)

c.  Solid solutions (alloys)

2.  Parts of a solution

a.  Solute - the substance being dissolved

b.  Solvent - the substance doing the dissolving

3.  The dissolving process

a.  The solvent molecules cluster around the solute molecules

b.  The solvent molecules pull the solvent molecules away from each other

c.  The moving solvent molecules spread the solute molecules equally throughout the solution

4.  Increasing the rate of dissolving in most liquid solutions

a.  Stirring

b.  Powdering the solute

c.  Increase the temperature of the solvent

5.  Increasing the rate of dissolving in gas-liquid solutions

a.  Cooling

b.  Increase pressure

B.  Solubility and Concentration

1.  Solubility is the maximum number of grams of solute that will dissolve in 100g of solvent at a certain temperature

2.  Concentration refers to amount of solute in the solvent

a.  Liquid-liquid solutions may be expressed by percentage by volume

b.  Solid-liquid solutions may be expressed by percentage by mass

c.  Solid-liquid solutions may be expressed by mass per liter of solution

3.  Limits of solubility

a.  Saturated solutions have all the solute dissolved as possible at a certain temperature

b.  Unsaturated solutions could dissolve more solute

c.  Supersaturated solutions contain more solute than a saturated solution has at a certain temperature

1)  Unstable situation

2)  Solute will quickly crystallize if disturbed

C.  Particles in Solution

1.  "Like dissolves like"

2.  Electrical conductivity of solutions

a.  Water solutions of ionic compounds and polar compounds conduct electricity

b.  Ionic compounds dissociate in solution causing ionization

c.  Electrolytes are ions in a water solution

d.  Nonelectrolytes are particles that do not conduct electricity in water solutions

3.  Freezing point depression - adding solute to a solvent lowers the freezing point of the solvent

          4.  Boiling point elevation - adding solute to a solvent raises the boiling point of the solvent