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
