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Properties of Solutions
CA StandardsStudents know the definitions of solute and solvent.
Students know how to describe the dissolving process at the molecular level by using the concept of random molecular motion.
Students know temperature, pressure, and surface area affect the dissolving process.
Classification of Matter
Solutions 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
“Like Dissolves Like”
Fats Benzene
Steroids Hexane
Waxes Toluene
Polar and ionic solutes dissolve best in polar solvents
Nonpolar solutes dissolve best in nonpolar solvents
Inorganic Salts Water
Sugars Small alcohols
Acetic acid
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.
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
An electrolyte is:
A substance whose aqueous solution conducts an electric current.
A nonelectrolyte is:
A substance whose aqueous solution does not conduct an electric current.
Definition of Electrolytes and Nonelectrolytes
The ammeter measures the flow of electrons (current) through the circuit.
If the ammeter measures a current, and the bulb glows, then the solution conducts.
If the ammeter fails to measure a current, and the bulb does not glow, the solution is non-conducting.
Electrolytes vs. Nonelectrolytes
1.Pure water2.Tap water3.Sugar solution4.Sodium chloride solution5.Hydrochloric acid solution6.Lactic acid solution7.Ethyl alcohol solution8.Pure sodium chloride
Try to classify the following substances as electrolytes or
nonelectrolytes…
ELECTROLYTES: NONELECTROLYTES:
Tap water (weak)
NaCl solution
HCl solution
Lactate solution (weak)
Pure water
Sugar solution
Ethanol solution
Pure NaCl
Answers to Electrolytes