Solubility the maximum amount of a substance that can be dissolved

Solubility Solubility is a physical property. Dissolving is a physical change. When something dissolves a reaction does NOT occur. Nothing new is created.

Solutions are homogeneous mixtures Solvent + Solute = Solution

Solute The solute is what dissolves It is the substance there is less of –Example: If you want to make iced tea, you need the sugar and water. –Sugar = SOLUTE

Solvent The solvent does the dissolving: –Water dissolves many substances so we call it the universal solvent. –In a mixture, it is the substance that we have MORE of.

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. The opposite is true for gas!

Its easier to dissolve sugar in hot tea than in iced tea!

Examine the graph A Lot more sugar will dissolve in higher temperatures Salt is only a little more soluble at higher temperatures

Which is salt? Which is sugar?

Sugar Salt A lot more dissolves in the hot water There is not much difference in how much salt dissolves in hot water

Factors Affecting Solubility 2. Temperature For all gases, solubility decreases as the temperature rises. So more gas is dissolved when the solution is cold

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.

See more molecules of gas dissolve when there is a lot of pressure

Does pressure alter the solubility of solids or liquids? No! Only the solubility of gasses change with pressure.

Solubility of Gases When the cap on a bottle of soda pop is removed, pressure is released, and the gas solute bubbles out.

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 solute is smaller it touches more solvent and will dissolve better.

How fast dissolving occurs depends on: 2. Stirring allows all of the solute particles to touch fresh solvent. This will help the solute dissolve.

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. If there is a lot of solute in the solution, then there is less room and solute will dissolve slowly.

Interpreting graphs

At 80C, if we have 350 g of sugar in 100 ml of water is this saturated, supersaturated or unsaturated?

At 80C, if we have 350g of sugar in 100 ml of water is this….saturated. We can’t dissolve more sugar in the water.

There is undissolved solute in a Saturated Solution

At 80C, if we have 100 g of sugar in 100 ml of water is this saturated, supersaturated or unsaturated?

At 80C, if we have 100 g of sugar in 100 ml of water is this….unsaturated. We can dissolve more sugar in the water.

At 80C, if we have 500 g of sugar in 100 ml of water is this saturated, supersaturated or unsaturated?

At 80C, if we have 500 g of sugar in 100 ml of water is this…. supersaturated. We can’t dissolve more sugar in the water.

Unsaturated and supersaturated solutions look the same

But IF we try to add 1 more crystal of solute to a supersaturated solution

We get rapid crystallization. All the other solute starts to fall out!

Insoluble cannot dissolve in that solvent so…we don’t get solutions we get suspensions