States of matter – solids and liquids
Fluid: a substance that can flow and therefore take the shape of its container
Surface tension: a force that tends to pull adjacent parts of a liquid’s surface
together, thereby decreasing the surface area
Surfactant: (surface active agent) decreases the surface tension of water by
interfering with the Hydrogen bonding between water molecules
Soaps and detergents
Allows the water to be attracted to other particles such as dirt, grease, etc.
Capillary action: the attraction of the surface of a liquid to the surface of a
solid – causes the meniscus when water is in a glass cylinder
Phase changes occur because of changes in energy!
Vaporization: Change from liquid to gas - there are two methods –both require the
addition of energy
evaporation: process by which particles escape from the surface of a
nonboiling liquid and enter the gas state
Evaporation is what occurs when you leave a glass of water sitting out
Boiling: rapid conversion of liquid into gas – caused by the vapor
pressure inside the liquid being equal to the atmospheric
pressure around the liquid
boiling occurs because of pressure – you can add heat and build pressure
inside the liquid or you can lower the external pressure to meet to liquid’s
internal pressure – either way boiling will occur
Equilibrium vapor pressure: pressure exerted by a vapor in
equilibrium with its corresponding liquid at a given
temperature
Boiling point: Temperature at which equilibrium vapor pressure of the liquid
equals the atmospheric pressure
Normal = 1 atmosphere
Normal boiling point: temperature at which
a substance will boil at 1 atm of pressure
For water it is 100OC or 212OF
Volatile liquid: liquid that evaporates readily at room temperature
These substances have low boiling points
NOT the same as explosive – although many volatile substances are also
explosive vapors
Molar heat of vaporization: amount of heat energy needed to vaporize one mole of
a liquid at its boiling point
NOT the energy to get the liquid to the boiling point – just the energy to change it
into a vapor once it has reached its boiling point
q = m Hv
formula to calculate the energy for a phase change from liquid to gas
To calculate the energy for 200 g of water –
q = (200 g)(2260 J/g)
q = 452000 J = 500000 J (with sig figs)
Vaporization is an ENDOTHERMIC process – whether it is evaporation
or boiling
Endothermic means you have to add heat – you have to turn on the
burner to get a pot of water to boil
Condensation: gas to liquid – caused by removing heat from the gas or the air no
longer being able to hold the gas
You have now looked at converting from liquid to gas and back again –
next we will look at liquid to solid and back again.
Freezing: physical change from liquid to solid by the removal of heat
Freezing point: temperature at which the solid and liquid states are in equilibrium
Normal freezing point: temperature at which a liquid becomes a solid at 1 atm.
Molar heat of fusion: amount of heat energy required to melt one mole of a
solid at its melting point
Again the formula for the actual conversion from one state to another is:
q=mHf
Melting: physical change of a solid to a liquid by the addition of heat
Melting point: temperature at which a solid becomes a liquid
Since we have looked at solid to liquid and back again,
we will investigate the solid phase a little more in-depth
Crystalline solid: simply means it contains crystals; consist of crystals
Crystal: a substance in which the particles are arranged in an orderly, geometric,
repeating pattern.
Examples would be diamond, quartz, table salt, emeralds, etc.
Crystal structure: the total three-dimensional arrangement of particles of a crystal
Amorphous solid: particles are arranged randomly – “without shape” – an
example would be soot as seen here – no regular pattern (crystal)
Isomorphous: crystals of different solids with the same crystalline
structure – any substances that have the same crystal look –
ie. Ruby, emerald, sapphire
Polymorphous- a single substance having two or more crystalline shapes.
ie: Carbon- graphite, diamond, soot or coal, etc
Unit cell: smallest portion of a crystal lattice that shows the three
dimensional pattern of the entire lattice – simplest unit of a crystal
There are 14 known unit
cells – the 7 to the left here
are just samples
Supercooled liquid:
substance that retains
certain liquid
properties even at
temperatures at which
they appear solid
**HONORS  Unit cells that you need to know –
draw these 3 in your notes
Simple cubic:
Body centered Cubic:
Face centered cubic:
There are 4 types of crystals:
1) Ionic – these are ionic compounds – (metal/nonmetal usually)
2) Covalent network – these are covalent compounds that are usually
solid at room temperature – ie. Quartz, diamond, glass
3) Covalent molecular – these are covalent compounds that are
usually gases at room temperature – ie. CO2, Ar, CO, NO2
4) Metallic – can be either pure metals or alloys
Hydrated crystal- crystal which contains hydrated ions (H2O molecules bonded
to ions in the crystals.)
Written as  CuSO4. 5H2O
Anhydrous- without water
A hydrated crystal can become an anhydrous crystal by heating to remove the
water (drying the crystal)
Also an anhydrous crystal can become hydrated by simply adding water
Hygroscopic: A crystal that
starts out as anhydrous and
captures water itself to make
itself hydrated – it captures the
water directly from the air.
An example would be the little
white silica packs you find in
shoes and electronics – they are
suppose to keep the moisture
from harming whatever they are
packed with
Deliquescent- Substances so hygroscopic that they take up enough water from the
air to dissolve and form a solution
NaOH is an example of a substance that is deliquescent
**HONORS  Liquefaction- Condensation of substances that are normally gasses
This is how you get liquid nitrogen
Sublimation – change from solid directly to a gas
ie. – ice in the freezer or snow on a below freezing day
Deposition: reverse of sublimation the gas is changed directly into a solid
ie. - frost on your car in the morning
EQUILIBRIUM:
dynamic condition in which two opposing
processes/changes occur at equal rates in a closed system
Le Chatlier’s principle: when a system at equilibrium is disturbed by the application
of a stress, it attains a new equilibrium position that minimizes the stress
STRESS = concentration, pressure, or temperature – change any of these 3 and
you cause the system to “shift”
Think of Le Chatlier as a see-saw – what happens on one end must be
balanced by a move either toward something missing or away
from something added
When extra NH3 is added to the following system at equilibrium:
3 H2(g) + N2(g) <--> 2 NH3(g)
The system will “shift” to the left or toward the reactant.
(Adding more NH3 increases the concentration of NH3 and that is a stress)
Another generic example:
Solid + heat  liquid
Adding heat will cause a shift to the right
Adding liquid will cause a shift to the left
• Adding more reactant will drive the forward reaction.
• Adding more product will drive the reverse reaction.
• Removal of reactants or products will shift the equilibrium in the direction
needed to produce more of the substance that was removed.
2 NO2 (g)  N2O4 (g) + 58.0 kJ
Predict the effect of each of the following changes on this system at
equilibrium (drive forward reaction, drive reverse reaction, no effect).
a) add N2O4
b) remove NO2
c) increase the volume
d) decrease the temperature
e) Add N2
Answers:
a) Shift left toward reactants or reverse
b) Shift left or reverse
c) Shift left – because increasing the volume decreases the pressure and the side
with the most gas is most effected by pressure – so the reactant side has 2
moles of gas and the drop in pressure is similar to removing something from the
reactant side
d) Shift right toward the products – because the heat is on the product side –
removing heat cause the shift toward the removed piece
e) NO effect – it is not involved in the reaction – only temp., pressure, and
concentration of substances involved in the reaction can cause stress
Do NOT copy the next slide – just READ it
Phase diagram- graph of pressure vs. temp. that shows the conditions under
which they phases of the substance exists.
Triple point- indicates the temp. and pressure conditions at which the solid, liquid,
and vapor of a substance can coexist
Critical point- point where critical temp. and critical pressure cross on the diagram
Critical temp.- Temperature above which the substance cannot exist in the
liquid state. (Tc=373.99OC for H2O)
Critical pressure- (Cp) lowest pressure at which the substance can exist as
a liquid at the critical temp. Pc(H2O)= 217.75 ATM.
Copy the
graph
without
the
numbers
Freeze drying- method of preserving food
Freeze the food, allow the water to sublimate and now you have frozen and dry
food = freeze dried
Add water and you re-hydrate the food
water
•Most important liquid on earth, 75% of the earth.
•Many unique properties due to hydrogen bonding
Hydrogen bonding- Attractive force, not as strong as an actual bond, between
H+ and an electronegative element in another molecule – must involve F, N, or
O to be hydrogen bonding – this is the force that holds DNA together
Water has 4 hydrogen bonds when frozen – may have 12 or more in the liquid
phase – this is why water expands when it freezes
Bond angle between H is 105 degrees
Water has a high heat capacity- this means it will hold a lot of heat – that’s why
the first few nights in fall when the air temperature is below freezing the ponds
don’t freeze
Water has the highest heat vaporization of any room temp. liquid.
high heat of vaporization means it takes a lot of energy to get water to
vaporize – this allows us to sweat and stay cool – in order for the sweat to
leave our skin it has to vaporize – this requires the addition of heat, where
does this heat come from? – our bodies – the heat the water takes as it
evaporates makes us feel cooler
Water is most dense at 4OC. – allows 4OC water to stay on the bottom of bodies of
water
This fact creates circulation in spring and fall in ponds and lakes
As the water cools it sinks, then when water drops below 4OC it stays on top - top
freezes, bottom is still 4OC (you do not have to draw these pictures)
Assignment:
Page 403 # 18-22
Page 409 #24-26
Page 414 #31,35,43,44,49,50,53,54,55,57,58,60