Transcript Modern Chemistry Chapter 12

Modern Chemistry Chapter 12Solutions
Section 1- Types of Mixtures
• Solutions are
homogeneous mixtures of
two or more substances
in a single phase.
– Soluble describes a
substance as capable of
being dissolved.
– Solvent is the dissolving
medium in a solution.
– Solute is the substance
that is dissolved in a
solution.
Types of Solutions
• Solutions can be in
any of the three
common physical
states.
 solid- a mixture of
metals called an alloy
 liquid- salt water,
sugar water, KoolAid…
 gas- the atmosphere
Suspensions & Colloids
• A suspension has
large particles that
settle out of a solvent.
eg. muddy water
• A colloid has
intermediate size
particles. Also called
an emulsion or a
foam.
Solutes:
electrolytes vs. nonelectrolytes
• An electrolyte is a
substance that dissolves
in water to give a solution
that conducts electricity.
• A nonelectrolyte is a
substance that dissolves
in water to give a solution
that does NOT conduct
electricity.
• Do section review
questions #1, #2, & #6 on
page 406.
Section 2- The Solution Process
• Factors that affect the rate of solution (how
quickly a substance dissolves):
– Any process that increases the number of
contacts between the solvent and the solute
will increase the solution rate.
• increasing the surface area of the solute
• agitating (shaking or stirring) the solution
• heating the solvent
Solutions
• Solution equilibrium is the physical state in which the
opposing processes of dissolution and crystallization
occur at equal rates.
• A saturated solution contains the maximum amount of
dissolved solute.
• An unsaturated solution contains less than the
maximum amount of dissolved solute.
• A supersaturated solution contains more dissolved
solute than a saturated solution.
Solubility
•
Solubility is a measurement of how much solute will dissolve in a specific
amount of solvent at a specific temperature to make a saturated solution.
•
“Likes dissolve likes”- polar solvents dissolve polar solutes & nonpolar
solvents dissolve nonpolar solutes.
•
Hydrationis the solution process with water as the solvent.
•
Hydrates are ionic compounds that have formed crystals that have
incorporated water molecules in their structure.
•
Immiscible liquids are not soluble in one another. eg. oil & water
•
Miscible liquids dissolve freely in one another in any proportion. eg. water
& alcohol
Solubility
•
Increasing the pressure has no effect on the solubility of a solid in a liquid
but does increase the solubility of gases in a liquid.
•
Increasing temperature often increases the solubility of a solid in a liquid but
decreases the solubility of a gas in a liquid.
•
Henry’s Law states that the solubility of a gas in a liquid is directly
proportional to the partial pressure of the gas on the surface of the liquid.
•
Effervescence is the rapid escape of a gas from a liquid in which the gas is
dissolved.
•
A solvated solute particle is surrounded by solvent molecules.
•
Enthalpy of solution is the amount of heat absorbed by a solution when a
specific amount of solute dissolves in a solvent.
Problems
• Do section review
questions #1, #2, #3,
#5, & #6 on page 416.
• Read the CrossDisciplinary
Connection on page
417 and answer the
questions at the end
of the reading.
Section 3
Concentrations of Solutions
• The concentration of a solution is a measure of
the amount of solute dissolved in a given
amount of solvent or solution.
• Molarity (M) is the number of moles of solute in
one liter of solution.
M = #mol
L
• Do practice problems #1, #2, & #3 on page 421.
Solution Concentrations
• Molality (m) is the concentration of a
solution expressed in moles of solute per
kilogram of solvent.
m = #mol
kg
Do practice problems #1 & #2 on page 424.
Solution Concentrations
• Percent composition by mass (%) is a
concentration that expresses the percent
of solute in a solution.
% = #g solute x 100
# g solution
Do section review problems #1, #2, & #3 on page 424.
Chapter 12 Test Review
• multiple choice (30)
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define & identify suspensions & solutions
define an alloy
define & identify electrolytes & nonelectrolytes
factors that affect the rate of dissolution
definitions of unsaturated, saturated & supersaturated solutions
general rules for predicting whether a solute is soluble in a
solvent
definition of solubility
effects of temperature & pressure on the solubility of gases and
solids in liquids
definitions of molarity (M) and molality (m)
solving molarity & molality problems
FORMULAS:
M = #mol/L
m = #mol/kg