A suspension is a mixture containing particles that settle out if left undisturbed. A suspension mixture can also be filtered.
A COLLOID MIXTURE IS NOT A SOLUTION
A solution is a homogeneous mixture (same phases: solid, liquid, gas)
A colloid mixture would be heterogeneous (different phases)
MMMMMMM…
Think salt water versus septic tank water.
COLLOID
A heterogeneous mixture of mid-sized solution particles
Adding an electrolyte will disrupt the electrostatic charges that hold the solute in the solution.
Heating it up will also cause a colloid to settle.
WHAT WOULD HAPPEN IF WE ADDED SALT TO THIS?
BROWNIAN MOTION
The erratic movement of colloid particles
TYNDALL EFFECT
Light is scattered through a colloid mixture.
If a colloid mixture were so dilute that it looked like an aqueous solution, a flashlight can solve the mystery.
IMMISCIBLE MISCIBLE
IMMISCIBLE
Two liquids that can be mixed together but separate shortly after they are mixed.
MISCIBLE
Two liquids that are soluble in each other in any proportion.
CONCENTRATION
How much solute is dissolved in a specific amount of solution.
% by mass % by volume Molarity Dilution Equation
DILUTING STOCK SOLUTIONS
If you know the concentration and volume of the solution you want to prepare, you can calculate the volume of stock solution you will need.
M1V1 = M2V21V1 = M2V2
What volume, in milliliters, of 2.00 M calcium chloride (CaCl2 ) stock solution would you use to make 0.50 L of 0.300M calcium chloride solution?
“LIKE DISSOLVES LIKE”
The process of surrounding
solute particles with solvent particles.
ENDO- AND EXOTHERMIC:
Energy is needed to make the solvent particles ‘open up’ to allow a solute particle to get squeezed in between the solvent particles. This is an endothermic process (takes energy).
When the solvent particles mix, the particles attract each other, giving off energy (exothermic process)
The overall energy change that occurs during the formation of the solution is called the Heat of Solution.
To increase the rate of solvation shake it up, increase the surface area, or heat it up.
THE HEAT OF SOLUTION
Solvation
Solubility of gases
Gases are less soluble at higher temperatures. The velocity (speed or kinetic energy) of the gas particles is so great that the gas escapes the solution.
Solvation
Pressure and Henry’s law Pressure affects the
solubility of gaseous solutes in solutions.
The solubility of a gas in any solvent increases as its external pressure (the pressure above the solution) increases.
Solvation
Henry’s Law: at a given temperature, the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquid.
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Colligative PropertiesColligative PropertiesOn adding a solute to a solvent, the properties On adding a solute to a solvent, the properties
of the solvent are modified.of the solvent are modified.
• Vapor pressure Vapor pressure decreasesdecreases
• Melting point Melting point decreasesdecreases
• Boiling point Boiling point increasesincreases
• Osmosis is possible (osmotic pressure)Osmosis is possible (osmotic pressure)
These changes are called These changes are called COLLIGATIVE COLLIGATIVE PROPERTIESPROPERTIES. .
They depend only on the They depend only on the NUMBERNUMBER of solute of solute particles relative to solvent particles, not on particles relative to solvent particles, not on the the KINDKIND of solute particles. of solute particles.
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Change in Freezing Change in Freezing Point Point
The freezing point of a solution is The freezing point of a solution is LOWERLOWER than that of the pure solventthan that of the pure solvent
Pure waterPure waterEthylene glycol/water Ethylene glycol/water
solutionsolution
19Change in Freezing Change in Freezing Point Point
Common Applications Common Applications of Freezing Point of Freezing Point DepressionDepression
Propylene glycol
Ethylene glycol – deadly to small animals
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Common Applications Common Applications of Freezing Point of Freezing Point DepressionDepression
Which would you use for the streets of Bloomington to lower the freezing point of ice and why? Would the temperature make any difference in your decision?
a) sand, SiO2
b) Rock salt, NaCl
c) Ice Melt, CaCl2
Change in Freezing Change in Freezing Point Point
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Change in Boiling Point Change in Boiling Point Common Applications Common Applications
of Boiling Point of Boiling Point ElevationElevation
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Boiling Point Elevation Boiling Point Elevation and Freezing Point and Freezing Point
DepressionDepression ∆∆T = K•m•iT = K•m•ii = van’t Hoff factor = number of particles i = van’t Hoff factor = number of particles
produced per molecule/formula unit. For produced per molecule/formula unit. For covalent compounds, i = 1. For ionic covalent compounds, i = 1. For ionic compounds, i = the number of ions compounds, i = the number of ions present (both + and -)present (both + and -)
CompoundCompound Theoretical Value of iTheoretical Value of iglycolglycol 11NaClNaCl 22
CaClCaCl22 33
CaCa33(PO(PO44))22 55
Colligative Properties
Sodium chloride (NaCl) is often used to prevent icy roads and to freeze ice cream.
What are the general effects of adding sugar to water?
Sodium chloride? Calcium chloride? Lithium
phosphate?
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