Properties of Solutions

Classification of MatterSolutions are homogeneous mixtures

SoluteA solute is the dissolved substance in a solution.

A solvent is the dissolving medium in a solution.

Solvent

Salt in salt water Sugar in soda drinks

Carbon dioxide in soda drinks

Water in salt water Water in soda

Solubility

If less than one gram of the substance will dissolve in 100 grams (or 100 mL) of solvent, the substance is considered insoluble.If more than ten grams of substance will dissolve in 100 grams (or 100 mL) of solvent, the substance is considered soluble.If between one and ten grams of a substance will dissolve in 100 grams (or 100 mL) of solvent, the substance is considered moderately soluble.

“Like Dissolves Like”

Fats Benzene

Steroids Hexane

Waxes Toluene

Inorganic Salts Water

Sugars Small alcohols

Acetic acid

Polar and ionic solutes dissolve best in polar solvents

Nonpolar solutes dissolve best in nonpolar solvents

Solubility of Ionic Compounds in Water The polar charges on water

molecules are attracted to the opposite charge on the ions in ionic compounds

If this attraction causes the ions to separate (“dissociate”), then the ionic compound “dissolves”

Ionic compounds that are soluble, always form ions in solution

Soluble Ionic Compounds

K2CrO4(aq) + Ba(NO3)2(aq)

Solubility of NaCl in Water

Salt Solution.mht

An electrolyte is: A substance whose aqueous solution

conducts an electric current Ionic compounds form electrolytes when

they dissolve, because the ions separate and move around independently

A nonelectrolyte is: A substance whose aqueous solution does

not conduct an electric current Molecular compounds do not form

electrolytes when they dissolve

Electrolytes and Nonelectrolytes

Electrolytes vs. Nonelectrolytes

Solubility of Molecular Compounds in Water•If we are comparing the water solubility of two similar molecules, the one with the higher percentage of the molecule that is polar (hydrophilic) is expected to have higher water solubility.

•We predict that the molecule with the higher percentage of its structure that is nonpolar (hydrophobic) to be less soluble in water.

Hydrophobic and Hydrophilic

Methamphetamine

Triglycerides (Fats and Oils)

Tristearin

Tristearin –Line Drawing

Making Soap

Soap and Detergent

Cleaning Greasy Dishes

Oil Droplets and Soap or Detergent

Solubility Trends

The solubility of MOST solids increases with temperature.

The rate at which solids dissolve increases with increasing surface area of the solid.

The solubility of gases decreases with increases in temperature.

The solubility of gases increases with the pressure above the solution.

Using Coffee…

Cold Warm Hot Water Water Water

Solubility and Temperature

Temperature affects how much solute dissolves (solubility)

Temperature affects how quickly a solute dissolves (rate)Increasing the temperature not only increases

the amount of solute that will dissolve but also increases the rate at which the solute will dissolve

Therefore…Solids tend to dissolve best when:

o Heatedo Stirredo Ground into small particles

Gases tend to dissolve best when:o The solution is cold

o Pressure is high

Solubility Chart