Slide 2 Ch. 14/15 Solids, Liquids and Solutions Slide 3
Intermolecular Forces Dipole-dipole attraction Between particles
with charged sides Between particles with charged sides
http://dwb4.unl.edu/ChemAnime/DIPOLED/DIPOLED.ht ml Hydrogen bonds
- Strongest Hydrogen bonds - Strongest Between Hs & F, O, N on
other molecules Dispersion forces - Weakest Caused by electrons
shifting towards one end of a molecule. Forces of attraction
between different molecules rather than bonding forces within the
same molecule. Slide 4 Water: The Magnificent Dipole One side of
water is negatively charged because the oxygen atom keeps the
shared electrons longer than the hydrogen atoms. As a result the
oxygen side is negatively charged and the hydrogen side of water is
positively charged. O Slide 5 It is its polarity and hydrogen
bonding that give water its many unusual Properties! i.e. high
boiling point, expansion upon freezing, and surface tension Slide 6
Hydrogen bonds - Strongest Between Hs & F, O, N on other
molecules IceLiquid Slide 7 Water is always trying to pull itself
into a tight ball as long as there is nothing nearby that has a
charge on it. Therefore, this surface is not repelling water; its
simply not attracting it and keeping water from doing what it does
naturally. Water pulls on itself so much that it forms a skin. Its
called surface tension. Slide 8 Wax does not repel water Weve heard
that wax or oils repel water. But that isnt true. Water is so
attracted to other water molecules that anything between them is
squeezed out of the way. O O Oil droplet O O O Slide 9 Forces and
Phases o Substances with very little intermolecular attraction
exist as gases o Substances with strong intermolecular attraction
exist as liquids o Substances with very strong intermolecular (or
ionic) attraction exist as solids Slide 10 Vapor gaseous state of a
substance that is not normally a gas at room temperature. Volatile
evaporates rapidly (due to weak intermolecular forces) Ex. thin
liquids Viscous evaporates slowly (due to strong intermolecular
forces) Ex. thick liquids V is for Vocabulary! Slide 11 Phase
Differences Slide 12 Three Phases of Matter Slide 13 Liquids A
decrease in the average kinetic energy of gas particles causes the
temperature to decrease. A decrease in the average kinetic energy
of gas particles causes the temperature to decrease. As it cools,
the particles tend to move more slowly, if they slow down enough,
attractive forces - called van der Waals forces pull them very
close together so they can only slip & slide past each other.
As it cools, the particles tend to move more slowly, if they slow
down enough, attractive forces - called van der Waals forces pull
them very close together so they can only slip & slide past
each other. It is now in liquid form! Condensation Change of a gas
to a liquid Slide 14 The Nature of Liquids The conversion of a
liquid to a gas or vapor below its boiling point is called
Vaporization The conversion of a liquid to a gas or vapor below its
boiling point is called Vaporization (occurs at the surface of a
liquid) (occurs at the surface of a liquid) In an open container,
this process is called Evaporation In an open container, this
process is called Evaporation Particles near the surface with
enough kinetic energy that happen to bounce in the right direction
escape! Particles near the surface with enough kinetic energy that
happen to bounce in the right direction escape! Slide 15
Microscopic view of a liquid near its surface. Slide 16 The Nature
of Liquids Eventually the particles will lose energy and return to
the liquid state, or condense. Eventually the particles will lose
energy and return to the liquid state, or condense. What are the
odds that they will return to the original liquid? What are the
odds that they will return to the original liquid? What if we cover
the container? What if we cover the container? So, the particles
begin to evaporate, then some begin to condense. Eventually, the
number of particles evaporating will equal the number condensing
& the space above the liquid will be saturated with vapor So,
the particles begin to evaporate, then some begin to condense.
Eventually, the number of particles evaporating will equal the
number condensing & the space above the liquid will be
saturated with vapor Slide 17 A dynamic equilibrium now exists
where Rate of evaporation = rate of condensation Note that there
will still be particles that evaporate and condenseNote that there
will still be particles that evaporate and condense But, there will
be no NET changeBut, there will be no NET change It will not look
like there are changes taking place!It will not look like there are
changes taking place! Slide 18 Evaporation is a cooling process
Cooling occurs because particles with the highest energy escape
first Particles left behind have lower average kinetic energies;
thus the temperature decreasesParticles left behind have lower
average kinetic energies; thus the temperature decreases Similar to
removing the fastest runner from a race- the remaining runners have
a lower average speedSimilar to removing the fastest runner from a
race- the remaining runners have a lower average speed Evaporation
helps to keep our skin cooler on a hot day! Evaporation helps to
keep our skin cooler on a hot day! Slide 19 The Nature of Liquids A
liquid will evaporate faster when heated because the added heat
increases the average kinetic energy needed to overcome the
attractive forces so more particles have enough energy to escape! A
liquid will evaporate faster when heated because the added heat
increases the average kinetic energy needed to overcome the
attractive forces so more particles have enough energy to escape!
Slide 20 If you were to add a drop of water below the tube to the
left what would happen? It would rise to the top & evaporate.
What would it do to the surface of the mercury? (push it down!)
Vapor Pressure pressure exerted by vapor! Slide 21 ( Since
different liquids evaporate at different rates, they have different
vapor pressures (at the same temps) Slide 22 ( Which liquid is the
most volatile? Yes! Diethyl Ether! It depressed the mercury the
most (highest vapor pressure!) Slide 23 Vapor Pressures of Liquids
Which is the most volatile liquid here? Diethyl ether It has the
highest vapor pressure at any Temp. Which has the strongest forces
of attraction? Water Slide 24 A liquid boils when its vapor
pressure equals the external pressure, so the boiling point changes
if the external pressure changes. A liquid boils when its vapor
pressure equals the external pressure, so the boiling point changes
if the external pressure changes. Bubbles form throughout the
liquid, rise to the surface, and escape into the airBubbles form
throughout the liquid, rise to the surface, and escape into the air
Normal boiling point- is when the vapor pressure of a liquid equals
standard pressure. (1 atm) Normal boiling point- is when the vapor
pressure of a liquid equals standard pressure. (1 atm) Slide 25 The
boiling point (bp) is the temperature at which the vapor pressure
of the liquid is equal to the external pressure on the liquid The
boiling point (bp) is the temperature at which the vapor pressure
of the liquid is equal to the external pressure on the liquid VPBP
Direct relationship! Slide 26 Normal bp of water = 100 o C Normal
bp of water = 100 o C However, in Denver = 95 o C, since Denver is
1600 m above sea level and average atmospheric pressure is about
85.3 kPa (Recipe adjustments?) In pressure cookers, which reduce
cooking time, water boils above 100 o C due to the increased
pressureIn pressure cookers, which reduce cooking time, water boils
above 100 o C due to the increased pressure Slide 27 Boiling Point
of Water at Various Locations LocationFeet above sea level P atm
(kPa) Boiling Point ( C) Top of Mt. Everest, Tibet 29,0283270 Top
of Mt. Denali, Alaska 20,32045.379 Top of Mt. Whitney, California
14,49457.385 Top of Mt. Washington, N.H. 6,29378.693 Boulder,
Colorado5,43081.394 New York City, New York 10101.3100 Death
Valley, California-282102.6100.3 Slide 28 Vapor Pressures of
Liquids Normal bp when crossing here At any pt. on a curve line,
liquid is boiling Slide 29 SOLIDS If you cool a liquid, the
particles lose kinetic energy and slow down. If you cool a liquid,
the particles lose kinetic energy and slow down. If they slow down
enough, extra forces of attraction pull them in so close together
that they can only vibrate in place. If they slow down enough,
extra forces of attraction pull them in so close together that they
can only vibrate in place. Freezing change of a liquid to a solid.
Freezing change of a liquid to a solid. Slide 30 Types of Solids
Molecular solids Molecular solids Metallic solids Metallic solids
Ionic solids Ionic solids Covalent network solids (diamonds)
Covalent network solids (diamonds) Slide 31 Crystals or Crystalline
Solids Particles of crystals are arranged in repeating geometric
patterns Particles of crystals are arranged in repeating geometric
patterns NaCl Slide 32 Representation of Components in a
Crystalline Solid Crystal Lattice: The orderly, regular,
3-dimensional arrangement of particles (atoms, ions, etc.) in a
crystal. Slide 33 Unit Cell The smallest portion of a crystal
lattice that shows the three- dimensional pattern of the entire
lattice Ex. A cubic lattice system has 3 types of unit cells Slide
34 Table salt crystals are shaped like cubes. Table salt crystals
are shaped like cubes. Slide 35 Diamond, a form of carbon, is also
a crystalline solid. Diamond, a form of carbon, is also a
crystalline solid. the crystals are shaped something like
pyramids.the crystals are shaped something like pyramids. Slide 36
Non-crystalline solids Many solids do not form crystals- Amorphous
Many solids do not form crystals- Amorphous Their molecules do not
arrange into repeating patterns Their molecules do not arrange into
repeating patterns often because they are too large.often because
they are too large. No definite melting point No definite melting
point Examples: Examples: Glass - also called a super-cooled
liquidGlass - also called a super-cooled liquid many plastics,
soot, asphalt, buttermany plastics, soot, asphalt, butter Slide 37
PHASE CHANGES PHASE CHANGES change is physical state (melting,
freezing, boiling, condensing, sublimation, deposition) PHASE
CHANGES change is physical state (melting, freezing, boiling,
condensing, sublimation, deposition) BOTH PHASES present during a
phase change BOTH PHASES present during a phase change Temperature
remains constant during a phase change. Temperature remains
constant during a phase change. Sublimation change of a solid
directly to a gas (dry ice, iodine, snow) Sublimation change of a
solid directly to a gas (dry ice, iodine, snow) Deposition change
of a gas directly to a solid. Deposition change of a gas directly
to a solid. Slide 38 Heat (kilojoules) Temperature (C) 0 0 -20 20
60 Slide 39 A-B = Solid ice, temperature is increasing. Particles
gain kinetic energy, vibration of particles increases. Heating and
cooling curve for water heated at a constant rates. Ice Slide 40
B-C = Solid starts to change state from solid to liquid.
Temperature remains constant as energy is used to break
inter-molecular bonds. 0C H2O (s) H2O (l) Slide 41 C-D =
temperature starts to rise once all the solid has melted. Particles
gain kinetic energy. Liquid water Slide 42 D-E = Liquid starts to
vaporize, turning from liquid to gas. The temperature remains
constant as energy is used to break inter- molecular forces. H 2 O
( ) H 2 O (g) 100C Slide 43 E-F = temperature starts to rise once
all liquid is vaporized. Gas particles gain kinetic energy. steam
Slide 44 The heating/cooling curve for water Slide 45 Water phase
changes Temperature remains __________ during a phase change.
constant Kinetic energy increasing on slopes KE not changing during
phase changes Boiling condensation Melting freezing Slide 46 Phase
Diagram Represents phases as a function of temperature and
pressure. Slide 47 Classification of Matter Matter Pure Substances
ElementsCompounds Mixtures HomogeneousMixturesHeterogeneousMixtures
Also called solutions Slide 48 Solute The part of a solution that
gets dissolved the part in lesser quantity The part of a solution
that does the dissolving the part in greater quantity Solvent Salt
in salt waterSugar in soda drinks Carbon dioxide in soda drinks
Water in salt waterWater in soda Aqueous Solutions water solutions
Slide 49 Solutions occur in all 3 phases! SoluteSolventExample
GasGasAir LiquidGas Water Vapor in Air SolidGasMothballs GasLiquid
Seltzer Water LiquidLiquid Antifreeze in radiator, cocktail
SolidLiquid Salt water GasSolid Whipped cream LiquidSolid Fillings:
Hg in Ag SolidSolid Alloys: Brass, etc. Slide 50 like dissolves
like Two substances with similar intermolecular forces are likely
to be soluble in each other. non-polar molecules are soluble in
non- polar solvents Ex. Grease in gasoline Ionic compounds &
polar molecules are soluble in polar solvents Ex. Ethanol in water;
salt in water 12.2 Slide 51 When a salt dissolves in water, the
positive ions are attracted to the slightly negative ends of the
water molecules and the negative ions are attracted to the slightly
positive ends of the water molecules. They dissociate (separate)
The ions are more strongly attracted to each other. but they become
surrounded by water molecules and cant get back together! Solvation
where solvent molecules surround solute particles. Slide 52
Dissolving of solid sodium chloride. Slide 53 Water: the Universal
Solvent O O Na + Cl - O O O Slide 54
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Slide 55 A measure of how much a gas, liquid, or solid will
dissolve in a solvent. Slide 56 Factors Effecting Solubility The
solubility of MOST solids increases with an increase in
temperature. The rate at which solids dissolve increases with
increasing surface area of the solid. (crush them & stir them!)
The solubility of gases increases with decreases in temperature.
The solubility of gases increases with an increase of pressure
above the solution. Slide 57 Therefore Solids tend to dissolve best
when: o Heated o Stirred o Ground into smaller particles Gases tend
to dissolve best when: o The solution is cooler o Pressure is
higher Slide 58 CO 2 in and out of water When you see bubbles, its
a heterogeneous mixture not a solution! Solution Mixture Slide 59
Salt (NaCl) is very soluble in water. 350 g/liter. However, if
water evaporates, there will be too much salt for the water to hold
in solution. The salt begins to form crystals. A lake near Death
Valley is supersaturated with salt causing the salt to crystallize
out. Slide 60 Once a year the company who owns the lakes lets
visitors into the area to collect salt crystals. Slide 61 These are
some of the salt crystals collected. Slide 62 Solubility Solubility
maximum mass of solute that will dissolve in 100 g of solvent at a
given temperaturemaximum mass of solute that will dissolve in 100 g
of solvent at a given temperature varies with tempvaries with temp
based on a saturated solutionbased on a saturated solution Slide 63
Temperature and Solubility Solid solubility and temperature
solubility increases with increasing temperature solubility
decreases with increasing temperature 12.4 Slide 64 Solubility
Chart Slide 65 A solution that contains the maximum amount of
solute that may be dissolved under existing conditions is
saturated. A solution that contains less solute than it can is
unsaturated. A solution that contains more dissolved solute than it
should is supersaturated. Slide 66 Solubility SATURATED SOLUTION no
more solute dissolves UNSATURATED SOLUTION more solute dissolves
SUPERSATURATED SOLUTION becomes unstable, crystals form
concentration Slide 67 Solubility Chart Slide 68 Colligative
Properties Colligative Properties are those that depend on the
concentration of particles in a solution, not upon the identity of
the solute. Boiling Point Elevation Freezing Point Depression Vapor
Pressure Depression More particles in solution bigger effect on the
coll. property! Higher bp, lower fp, etc. Slide 69 Change in
Boiling Point Common Applications of Boiling Point Elevation Slide
70 Change in Freezing Point Common Applications of Freezing Point
Depression Propylene glycol Ethylene glycol deadly to small animals
Slide 71 Slide 72 Concentrations of Solutions The amount of solute
in a solution is given by its concentration. Concentration can be
expressed qualitatively or quantitatively Dilute contains small
amount of solute Concentrated contains large amount of solute
(words) (numbers) Slide 73 Molarity (M) = moles solute liters of
solution *Volume of solution MUST be in Liters! We will use
something called Molarity! Ex. What is the molarity of a solution
made by dissolving 3.5 moles of NaCl in a 4.3L solution? 3.5 moles
NaCl 4.3 L solution = 0.81 M NaCl (aq) Molarity can be labeled M or
mol/L Handy in conversion factors! Slide 74 PROBLEM: Dissolve 5.00
g of NiCl 2 in enough water to make 250 mL of solution. Calculate
the Molarity. Step 1: Calculate moles of NiCl 2 Step 3: Calculate
Molarity NiCl 2 [NiCl 2 ] = 0.154 M Step 2: convert mL to L 250
mL.250L Slide 75 Step 1: Change mL to L. 250 mL x 1L/1000mL = 0.250
L Step 2: Calculate. Moles = (0.0500 mol) (0.250 L) = 0.0125 moles
Step 3: Convert moles to grams. (0.0125 mol)(90.00 g/mol) = 1.13 g
oxalic acid moles = MV What mass of oxalic acid, H 2 C 2 O 4, is
required to make 250. mL of a 0.0500 M solution? *Rearrange formula
to solve for moles. 1 L Slide 76 Learning Check How many grams of
NaOH are required to prepare 400. mL of 3.0 M NaOH solution? 1)12 g
2)48 g 3) 300 g Slide 77 Preparing Solutions Weigh out a specific
mass of solid solute and dissolve in a given quantity of solvent.
Weigh out a specific mass of solid solute and dissolve in a given
quantity of solvent. Dilute a concentrated solution to give one
that is less concentrated. Dilute a concentrated solution to give
one that is less concentrated. M 1 V 1 = M 2 V 2 Slide 78 How would
you make 250 mL of 3.0 M HCl from a 6 M stock solution of HCl? M 1
V 1 = M 2 V 2 (250 mL) (3.0 M) = (6 M) (X) X = 125 mL How would you
make would require some words in the answer! So, Add enough water
to 125 mL of 6 M HCl to bring the total volume to 250 mL. Slide 79
Miscible where liquids dissolve in each other. Miscible where
liquids dissolve in each other. Ex. Ethanol in water Ex. Ethanol in
water Slide 80 Suspensions and Colloids Suspensions and colloids
are NOT solutions. Suspensions: The particles are so large that
they settle out of the solvent if not constantly stirred. Colloids:
The particles are intermediate in size between those of a
suspension and those of a solution. Slide 81 The Tyndall Effect
Colloids scatter light, making a beam visible. Solutions do not
scatter light. Which glass contains a colloid? solution colloid
Slide 82 Types of Colloids ExamplesDispersing Medium Dispersed
Substance Colloid Type Fog, aerosol spraysGasLiquidAerosol Smoke,
airborne bacteriaGasSolidAerosol Whipped cream, soap
sudsLiquidGasFoam Milk, mayonnaiseLiquid Emulsion Paint, clays,
gelatinLiquidSolidSol Marshmallow, StyrofoamSolidGasSolid foam
Butter, cheeseSolidLiquidSolid emulsion Ruby glassSolid Solid
sol
