Contributed by:
The highlights are:
1. Phases of matter
2. Change of phase
3. Energy
4. Energy during phase change
5. Heat flow and transfer
6. Heating and cooling curves
7. Heat equations
8. Specific heat capacity
9. Calorimeter
1.
Phases of Matter, Energy
and Phase Changes
2.
Phase of Matter
Depends on
strength of forces
of attraction
between particles.
3.
Solids
Definite shape and volume.
Most dense phase (Exception is water!)
Difficult to compress.
Particles vibrate in fixed positions
Crystalline lattice structure.
Most attraction between particles.
Note:
Amorphous solids include glass,
plastic, wax, and silly putty
4.
Liquids
Definite volume
No definite shape
Hard to compress
Particles slide past each
other
Forces of attraction
between particles still high
5.
Gases
No definite shape or volume
Expands to fill container
Lowest density
Little attraction between
particles
“Vapor” = a gaseous state of
something that is normally liquid
(Ex: water vapor)
6.
Changes in Phase
Gas
Condensation Vaporization (Boiling or Evaporating)
Liquid
Solidification Melting (fusion)
Solid
7.
Phase Changes
Short Summary video on phases: (1 min)
http://www.youtube.com/watch?v=s-KvoVzukHo&safe=active
Applet: (Excellent)
https://phet.colorado.edu/en/simulation/states-of-matter
http://www.harcourtschool.com/activity/states_of_matter/
8.
Let’s Skip a Phase
Sublimation
Directlyfrom the solid
phase to the gas phase.
Happens with substances
with weak intermolecular
forces of attraction
They separate easily!
Ex: CO2(s) dry ice, Iodine
CO2(s) → CO2 (g)
http://www.youtube.com/watch?v=8tHOVVgGkpk
9.
Energy
Energy = capacity to do work or produce heat.
It can be anything that causes matter to move or
change direction.
Many different types of energy
Ex: electrical, thermal, atomic, mechanical
“Chemical” energy is the potential energy stored in
the bonds between atoms
10.
Law of Conservation of Energy
Energy can’t be
created or
destroyed, just
transferred from
one form to another
11.
PE vs. KE
Potential Energy
stored energy
Energy can be stored in
bonds between atoms
KineticEnergy
energy of motion
Allatoms are moving
and vibrating unless at
absolute zero
12.
Energy and Changes to Matter
Exothermic Change: A + B → C + D + energy
Energy is released or “ex”its
Endothermic Change: A + B + energy → C + D
Energy is absorbed or “en”ters
13.
Energy During Phase Changes
Solid Liquid or Liquid Gas
Endothermic
Energy is absorbed and overcomes attractive
forces between particles
Add heat
14.
Gas Liquid, Liquid Solid
Exothermic
As particles come closer together energy is
released
Remove heat
16.
Heat Energy
Also
called Thermal energy, it makes particles
move more as it is added
Measured in Joules or calories.
http://www.youtube.com/watch?v=f1eAOygDP5s&safe=active
17.
Heat Flow or Transfer
Heat energy travels
from an object of
higher temp. to
one of lower temp.
until both reach
the same temp.
19.
Temperature
Measure of the average kinetic energy
(motion) of all the particles in a sample.
Not a form of energy!!!
Butif you add heat energy or take it away, it
causes particles to move faster or slower and
thus changes the temp.
Heat vs Temp.
https://www.youtube.com/watch?
v=yxBTEMnrZZk
20.
Heat vs. Temperature
Teacup vs. Bathtub
Both at 25˚C
Whichone contains
more heat energy?
Which one has the
greater average KE?
21.
Temperature Scales Used in
Chemistry
Fixed points of scale based on the freezing
point and boiling point of water
0 °C = water freezes, 100 °C = water boils
Scale based on lowest temperature possible
0 K = absolute zero
https://www.youtube.com/watch?v=-G9FdNqUVBQ
22.
Scales and
K = ˚C + 273
23.
Absolute Zero
Temperatureat which particles have
slowed down so much they no longer
possess any kinetic energy.
0 Kelvin
-273° Celsius
24.
Heating & Cooling Curves
Graphically represents temp. changes as heat
energy is added or taken away.
26.
Interpreting the Graph
Theslanted portions = Theflat portions =
temp is changing temp not changing
Single phase is heating Substance undergoing
up or cooling down a phase change
KE is changing PE is changing
27.
Heating Curve for Water
28.
What is Melting Pt? Boiling Pt?
29.
Heat Equations
Calculates
the energy involved when a
substance changes in temperature or
undergoes a phase change.
Usethis when temperature of substance
changes use this formula:
30.
When Undergoing Phase Change use one of
these formulas: TEMPERATURE CONSTANT
Q = mHf Use when changing from
solid to liquid (melting) or
liquid to solid (freezing)
Q = mHv Use when changing from
liquid to gas (vaporization)
or gas to liquid (condensing)
31.
Physical Constants for Water
Table B
Use these constants in Heat Equations
Hf = heat of fusion = 334J/g
Hv = heat of vaporization = 2260J/g
Specific Heat Capacity (“c”) = 4.18 J/g x K
32.
What is Specific Heat Capacity?
Specific Heat: “c”
Joules of heat needed to raise 1 gram of a
substance 1°C.
Substances have different abilities to absorb
heat when energy is applied depending on
their composition.
Ex: Piece of Iron vs. Water.
33.
Calorimeter
Instrument to determine amount of heat lost or
gained in a reaction by measuring changes in the
temp. of water surrounding the system.
Virtual Calorimetry
Q = mcΔT
34.
Multi-step Heat Problems (Honors)
Needto use more than one of the heat equations and
add up the total heat.
Note: Specific Heat of different phases of water!
H O(s) = 2.10 J/gx°C
2
H O (l) = 4.18 J/gx°C
2
H2O(g) = 1.84 J/gx°C
Ex:
Calculate the heat energy to raise 10 grams of
water at -25°C to 80°C.
Draw a heating curve. Figure out # of steps.
1.) Heat ice from -25° to 0° q = mcΔT
2.) Melt ice to liquid at 0° q = mHf
3.) Heat liquid water from 0° to 80° q = mcΔT
36.
Heat Lost = Heat Gained (Honors)
When two objects of different temperatures
are placed together in a closed system, heat
flows from hotter to colder object until they
reach same temperature.
mcΔT = mcΔT
Total heat lost = total heat gained
37.
Try This!!
Online App Demonstrates Specific Heat
and Calorimetry
http://elearning.classof1.com/demo/2D_Lab/Chemistry/
specificHeat/specificHeat.html
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