Solubility

A lava lamp depends on the globs not being soluble. It also depends on the globs being about the same density as water. It took years to develop the right ingredients to make a lava lamp work.

Polar MoleculesMolecules like water that have positive and

negative poles (like magnetic poles) are called POLAR. Molecules that do not have any negative or positive poles are called nonpolar.

Water’s Surface Tension•The strong attraction water has to itself is due to the plus to minus attraction.

• Water tries to pull itself into a spherical shape.

•This attraction also accounts for what's called "surface tension."

•Water molecules lock together to form a skin where water meets the air.

• Insects take advantage of this surface tension to stand on the surface.

DefinitionSolubility is the ability of a gas, liquid, or

solid to dissolve in water (or sometimes another liquid).

The motto regarding solubility is "Like Dissovles Like.”

• Nonpolar soap Polar water• dissolves nonpolar

dissolves• grease on hands

polar sugar• dishes.

to sweeten•

the tea.

Attraction of Water Molecules The plus end of water is attracted to the negative

end of a different water molecule.

They align themselves + to - .

Water Dissolving A Polar Compound•The substances that water is good at dissolving are those that have a charge.

• Here is sodium chloride (table salt).

•Sodium has a net plus charge because chlorine has taken one of sodium's electrons.

•This makes chlorine negative because it has an extra electron.

Continued:•The negative end of water pulls on the sodium atom .

•The positive end of other water molecules pull on the negatively charged chlorine. •Most salts like sodium chloride are easily pulled apart by water.

Factors that Affect Dissolving RateIncreasing the temperature usually

increases the solubility of solids in liquids. This means a greater average velocity for the particles.

It also allows them to move from one position to another more easily.

Stirring-brings more fresh solvent into contact with more solute.

Grinding the solute into smaller size particles. Smaller particles have more surface area than larger size particles

Nonpolar Molecules•To the left is a chain of carbon and hydrogen atoms.

•We call these hydrocarbons. This one is about 7 carbons long and is typical of gasoline.

• The bottom image shows the charges of a carbon atom attached to two hydrogens.

•You may notice that unlike water the charge is divided evenly.

•This explains why water will not break down a nonpolar molecule.

•Ex. Water will not break down gasoline.

Concentrated OJ – No water has been added to this solution.

Diluted OJ – Water hasbeen added to this solution.

Concentrations of SolutionsA concentrated solution has a relatively large (but non-

specific) amount of solute dissolved in a solvent.

A dilute solution has a smaller quantity of solute dissolved.

Dilute Lemonade Concentrated Lemonade

Not as much sugar dissolved as there More sugar

dissolvedcould be!!!! compared to the

other solution.

(Comparing the concentrations of dissolved sugar )

Examples of Concentrations in Solutions

Concentrations

Solute Less Than 50%

Solvent More Than 50%

Examples

Liquid Liquid Alcohol - Water

wine, beer, acetic acid

Solid Liquid Salt – Water Saline, Sugar water, Hard water (CaCO3)

Gas Liquid Oxygen - Water

Carbonated water (CO2), ammonia solution

Gas Gas Air = oxygen - nitrogen

Solid Gas smog

Solid Solid alloy brass

Making a Homogeneous SolutionSolute:The substance in the

smallest amount

the one that dissolves or disperses

Solvent:

Sugar

• The substance in the larger amount

• Substance doing the dissolving

Water: universal solvent

Water isn’t always the solventSolution with alcohol as solvent is called a tincture.

Solution made of two or more metals is called an alloy.

Properties of a Suspension:Suspension: is a heterogeneous

mixture with larger particles.

particles are visible and will settle out on standing.

Can be separated by filtering.

Examples : muddy water, tomato juice, orange juice with pulp

Muddy Water

Orange Juice with Pulp

Tomato Juice

Properties of a Colloid: Colloid: a heterogeneous

mixture with intermediate particle size between a solution and a suspension

Colloid particles may be seen in a beam of light (Tyndall effect)

Will not settle out.Examples: dust in air,

milk, fog, and jello.

Fog

Milk

Jello

Unsaturated, Saturated, and SupersaturatedSaturated : when a substance has dissolved in a solution and no more of it will dissolve under normal circumstances (room temperature, normal pressure). It has reached equilibrium

Unsaturated : just points before equilibrium is reached, so you can keep dissolving the substance into the solution. There is not as much solute dissolved in solution as it can hold.

Supersaturated: when the conditions are changed so that you can dissolve more of the substance into the solution than it would allow under normal conditions. If the solution is brought back to normal conditions, the substance will drop out of solution .

Tyndall EffectCaused by reflection of light

by very small particles in suspension in a transparent medium.

It is often seen from the dust in the air when sunlight comes in through a window, or comes down through holes in clouds.

Also, It is seen when headlight beams are visible on foggy nights

Miscible V’S Immiscible When two liquids

totally mix they are said to be miscible.

An example of this would be alcohol and water.

Ethanol and water are completely

miscible. No matter what ratio (%) they are dissolved.

When two liquids do not mix they are said to be immiscible.

An example would be oil and water.

Solubility Graph and Solubility CurveThe solubility of a substance for a given temperature

must be determined.

This is done by finding the mass of solute needed to make a saturated solution in a given amount of water for that temperature(referred to as the solubility)

This is repeated for each of the temperatures .

The data is then plotted on a temperature/solubility graph and the points are connected.

These connected points are called a solubility curve.