Solutions Chapter 15 & 16 Chemistry
ďƒ˜ Create a three circle venn diagram that
compares and contrasts the 3 examples of mixtures (Solutions, Suspensions, Colloids)
Making solutions Solute: Dissolved particles
Solvents: The thing that does the dissolving.
Solution: A homogenous mixture that contains solutes dissolved in solvents.
Solutions Homogeneous 0.01 – 1 nm solute particle; atoms, ions,
molecules Does not separate on standing Cannot be separated by filtration No light scattering
Colloids Heterogeneous 1 – 1000 nm dispersed particles; particles
or large molecules Does not separate on standing Cannot be separated by filtration Scatters light (Tyndall Effect)
Suspension Heterogeneous Over 1000 nm
suspended particles; large particles or aggregates Particles settle out Can be separated by filtration May scatter light, but not transparent
Colloids First discovered:
The particles are spread throughout the
dispersion medium (solid, liquid, gas). Cloudy or milky in appearance when
concentrated Look clear or almost clear when diluted
Colloids Dispersed Phase
State of matter that is in between the outer edge. Interior phase
Phase of matter it appears to be in
Flashes of light, or scintillations, are seen when colloids are studied under a microscope.
Caused by particles reflecting and scattering the light more erratically.
Colloidal particles tend to stay suspended because they become charged by absorbing ions from the dispersing medium onto their surface.
Some positively charged, some negatively charged.
Destroying a colloidal system
Adding ions having a charge opposite to that of the colloidal particles • They neutralize the charged colloidal particles • Particles clump together to form heavier aggregates and precipitate from the dispersion
Emulsions A colloidal dispersion of a liquid in a liquid.
Emulsifying agent is essential for the formation of an emulsion • Ex. Oils and greases are not soluble in water • Adding soap or detergent to water allows for mixtures to mix
Heterogeneous mixture of oil and vinegar • Egg yolk acts as emulsifying agent
Electrolytes ďƒ˜ A compound that
conducts electric current when it is in an aqueous solution or in the molten state. ď Ź
All ionic compounds (dissociate into ions)
Solvation Process Process by which the positive and negative ions of an ionic solid become surrounded by solvent molecules.
Nonelectrolytes A compound that does not conduct an
electric current in either aqueous solution or the molten state. Many molecular compounds are not electrolytes (no ions).
Sugar (sucrose), rubbing alcohol (2-propanol)
Review on your own (Chp. 15) Surface Tension Hydrogen Bonding Vapor Pressure Hydrates Deliquescents
Solutions Chapter 16 Sections 1 - 4
Using the pictures as a model…. Come up with a definition of the following
Saturated Unsaturated Supersaturated
A little earth science never hurts anyone. Another example that you learned everything in Earth Science already
Solubility Curves Saturated
Factors Affecting Solubility Temperature
Most solids • Substance solubility increases with Temperature Mineral deposits a result of cooling of solution of mineral water.
Cooling water holds less minerals
Factors Affecting Solubility Pressure
Little affect on solids and liquids Strong influence on Gases
Molarity Problem: Calculate the molarity of a solution containing 100 g of KCl in 500 ml of water. moles M= liters
1.34 moles Molarity = .5 liters
K 1 x 39.1 = 39.1 Cl 1 x 35.5 = 35.5 74.6 100 g
1 mol 74.6 g
= 1.34 mol
Molarity ďƒ˜ The number of moles of solute in one liter
of solution ďƒ˜ Molarity = # of moles of solute
---------------------------# of liters of solution Units - M
Percent by Mass Percent by mass of a solute in solution is
the number of grams of solute dissolved in 100 grams of solution.
% (m/m) = mass of solute / mass of solution x 100 Mass of solute + Mass of solvent
% (v/v) = volume of solute / volume of solution x 100 volume of solute + volume of solvent
% Mass and % Volume Products
Colligative Properties Property that depends on the number of
solute particles but is independent of their nature
solute (little tendency to
become a gas under existing conditions)
Lowers the vapor pressure of solvent Lowers the freezing point of solution Raises the boiling point of solution
Pressure exerted by a vapor that is in dynamic equilibrium with its liquid in a closed system.
Ease of vaporization Glucose, sodium chloride • When dissolved in a solvent, the vapor pressure of the solution is lower than the vapor pressure of the pure solvent.
Colligative Property: Vapor Pressure lowering
Molality ďƒ˜ The concentration of a solution expressed
in moles of solute per kilogram of solvent ďƒ˜ Molality = # of moles solute
--------------------------mass of solvent (kg) Units - m
Freezing Point Depression
A colligative property The difference in temperature between the freezing point of a solution and the freezing point of the pure solvent. ΔTf = Kf x d.f. x m ΔTf = Freezing point depression m = molality
Kf = molal freezing-point depression constant For Water (1.86°C/m) d.f. = Dissociation Factor (covalents it is one, Ionic it depends on ions it dissociates into)
Boiling Point Elevation
Boiling point = vapor pressure equals atmospheric pressure
Change in either causes a change in boiling point
Boiling point elevation of 1 molal solution of any molecular solute in water is 0.512 degrees Celsius ΔTb = Kb x
d.f. x m
ΔTb = Boiling Point Elevation m = molality
Kb = molal boiling-point elevation constant For Water (0.512°C/m) d.f. = Dissociation Factor (covalents it is one, Ionic it depends on ions it dissociates into)
Formation of a Solution Solvation Hydration
Solvent H2O Cl- Na+ salt Na+ Clsolute