Solubility

the maximum amount of a substance that can be dissolved

Solubility

• Solubility is a physical property.

• Dissolving is a physical change.

Solvent

• The solvent does the dissolving:– Water dissolves many

substances so we call it the universal solvent.

– When alcohol is used as the solvent, the resulting solution is called a tincture.

Solute

• The solute is what dissolves– Example: If you want

to make iced tea, you need the sugar and water.

– Sugar = SOLUTE– Water = SOLVENT

Solvent + solute = Solution

Checkpoint

• The ocean is made up of salt and water. Which one is the solute and which is the solvent?

Checkpoint

• The ocean is made up of salt and water. Which one is the solute and which is the solvent?

• Salt = solute

• Water = solvent

Making a solution• In order to make a solution, you

need to mix what you have together (sugar + water)– 1. The solute goes in the

solvent and the solute slowly breaks into pieces. 2. The molecules of the solvent begin to move out of the way to make room for the molecules of the solute. Example: The water has to make room for the sugar molecules. 3. The solute and solvent interact until the concentration of the two substances is equal throughout the system. The concentration of sugar in the water would be the same from a sample at the top, bottom, or middle of the glass.

Solvent + Solute = Solution

Types of Solutions:Solid Solvent + Solid

Solute (gold jewelry)

Solid Solvent + Liquid Solute (dental filling)

Solid Solvent + Gas Solute (gas mask filter)

Solvent + Solute = Solution

Liquid Solvent + Solid Solute (salt water)

Liquid Solvent + Liquid Solute (rubbing alcohol)

Liquid Solvent + Gas Solute (soda)

Solvent + Solute = Solution

Gas Solvent + Solid Solute (smoke, air freshener)

Gas Solvent + Liquid Solute (fog, humidity)

Gas Solvent + Gas Solute (air)

Checkpoint

• Which of the following would be considered a solution?– A. 14k gold– B. Salt water– C. Carbonated water– D. All of the above

Checkpoint

• Which of the following would be considered a solution?– A. 14k gold– B. Salt water– C. Carbonated water– D. All of the above

Answer: D. all of the above

Factors Affecting Solubility

1. The nature of the solute and solvent

200 grams of zinc chloride can dissolve in 100 grams of water

but only

1 gram of lead chloride can dissolve in 100 grams of water

Factors Affecting Solubility

2. Temperature

An increase in temperature increases the solubility of a solid solute.

For all gases, solubility decreases as the temperature rises.

Factors Affecting Solubility

2. Temperature

For all gases, solubility decreases as the temperature rises. Why?

Factors Affecting Solubility

2. Temperature

For all gases, solubility decreases as the temperature rises. Why?

More heat = more kinetic energy (bouncing off each other)

Factors Affecting Solubility

3. Pressure

Changes in pressure have no effect on the solubility of solids and liquids.

For gases, an increase in pressure increases solubility and a decrease in pressure decreases solubility.

Solubility of Gases

When the cap on a bottle of soda pop is removed, pressure is released, and the gas solute bubbles out. This escape of a gas from solution is called effervescence.

Checkpoint

• Why does soda go flat if you leave it out without a cap?

Checkpoint

• Why does soda go flat if you leave it out without a cap?

• Leaving the soda out without a cap means that there is less pressure in the system. Less pressure makes gases LESS soluble in a liquid.

How fast dissolving occurs depends on:

1. The size of the particles:Dissolving only takes place at the surface of each particle. When the total surface area is increased, the solute dissolves more rapidly. Breaking a solute into smaller pieces increases its surface area and hence its rate of solution.

How fast dissolving occurs depends on:

2. Stirring brings fresh portions of the solvent in contact with the solute, thereby increasing the rate of solution only for solids and liquids, NOT gases.

How fast dissolving occurs depends on:

3. The amount of solute already dissolved

When there is little solute already in solution, dissolving takes place rapidly.

As the solution approaches the point where no more can be dissolved, dissolving takes place more slowly.

How fast dissolving occurs depends on:

4. Temperature

For liquids and solid, increasing the temperature increases the rate at which the solute will dissolve.

For gases, the reverse is true. An increase in temperature decreases how fast dissolving occurs.

Making a supersaturated solution and creating a precipitate