Topic 2/3 Matter and Energy/Gases
Key Concept
Definitions and facts
1. Pure substances
Matter with fixed and
definite composition.
Always homogeneous.
Elements and Compounds.
Na H2 NH3
Composed of identical atoms
with same atomic number.
(see Periodic Table).
Cannot be decomposed into
smaller substances.
K
2. Elements
3. Compounds
4. Mixture
Key examples
Chemical combination of
two or more different
elements in fixed and
definite ratio.
Can be chemically
decomposed (broken down)
into smaller substances.
water, lithium
sodium chloride
Mg Co
Neon, boron
CO2 KClO3
ammonia
water
Physical combination of two
or more substances in
varying ratio.
Can be homogeneous
(solutions) or heterogeneous
NaCl(aq)
5. Homgeneous
Mixture with uniform
composition within the same
sample.
Aqueous (water) solutions
NH3(aq)
6. Heterogeneous
Mixture that has non-uniform
composition within a sample
concrete
Atoms in compounds are
combined in fixed and
definite ratio
Water, H2O will
always have
2 H : 1 O ratio
7. Law of Definite
Proportion
Salt water
Air
soil
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Topic 2/3 Matter and Energy/Gases
Key Concept
8. Distillation
9. Solid
10. Liquid
Definitions and facts
A process of separation by
boiling off substances in a
mixture at different boiling
points.
A phase with definite
volume and definite shape.
Particles in fixed regular
geometric arrangement.
Particles may vibrate.
Particles are incompressible.
A phase with definite volume
but no definite shape.
Particles are incompressible.
Examples
Salt water.
Gas mixture.
Au(s)
Fe(s)
H2O(l)
A phase with no definite
volume and no definite shape.
Particles are compressible.
CO2(g)
Solid to liquid phase change.
Endothermic (heat absorbed).
Au(s) ---- > Au(l)
13. Freezing
Liquid to solid phase change.
Exothermic (heat released).
Au(l) ---- > Au(s)
14. Evaporation
(vaporization)
Liquid to gas phase change.
Endothermic (heat absorbed).
H2O(l) -- > H2O(g)
15. Condensation
Gas to liquid phase change.
Exothermic (heat released).
H2O(g) -- > H2O(l)
16. Sublimation
Solid to gas phase change
Endothermic (heat absorbed).
CO2(s) -- > CO2(g)
17. Deposition
Gas to solid phase change.
Exothermic (heat released).
CO2(g) -- > CO2(s)
11. Gas
12. Melting
(Fusion)
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Topic 2/3 Matter and Energy/Gases
Key Concept
Definitions and facts
Examples
18. Heat Energy
heat
A form of energy that can
31oC
25oC
flow from High to Low area
flow
19. Joules (J) and
Units for measuring heat
I cal = 4.18 J
20. Exothermic
A process that releases heat
freezing
condensation
deposition
21. Endothermic
A process that absorbs heat
fusion/melting
evaporation
sublimation
22. Potential Energy
Stored energy in substances
23. Kinetic Energy
(KE)
Energy due to movement
24. Temperature
31oC
25oC
A measure of average
Kinetic Energy in substances Highest Lowest
Calories (cal)
KE
25. Standard
Temperature
26. Ice-liquid
equilibrium
27. Steam-liquid
equilibrium
KE
0oC or 273 K
A temperature at which the
solid and liquid are present
(freezing and melting points)
0oC or 273 K
A temperature at which the
solid and liquid are present.
(boiling point)
100oC or 373 K
(for water)
(for water)
28. Absolute Zero
A temperature at which all
molecular movements stop
-273oC or 0 K
29. Phase change
diagram
A diagram showing a
change of phase over time
(see page 8)
.
3
Topic 2/3 Matter and Energy/Gases
Key Concept
Definitions and facts
Examples
30. Specific heat
capacity
Heat to change a unit mass 4.18 J/g.oC
of a substance by 1oC
31. Heat of fusion
Heat to change a unit mass
of solid to liquid at constant 334 J/g
temperature.
32. Heat of vaporization
Heat to change a unit mass
of liquid to vapor(gas) at
constant temperature
32. Avogadro’s law
IL
Gases with same volume 1 L
50 K 50 K
at same temperature
2 atm 2 atm
and same pressure
have equal # of molecules
Gas A and B
contain equal
number of
molecules
A theoretical gas
33. Ideal gas
34. Kinetic Molecular
Theory of ideal gas
Explains behavior of gases
.Gas is individual particle
.Gas particles are
Far apart and in continuous
random straight-line motion.
.Gas particles have have
No volume and No
attraction to each other
.When particles collide,
energy is transferred
. Increase in temperature
causes increase in kinetic
energy of gas particles
4
2260 J/g
Topic 2/3 Matter and Energy/Gases
Key Concept
Definitions and facts
Examples
35. Real Gases that
behave most like
ideal gas
Lightest gases
H and He
behave most like an ideal gas (Lightest
gases)
Heaviest gases
behave least like an ideal gas behave most
like ideal gas
36. Conditions Real
Gases behave most
like ideal gas
Behave Most Like
under: High Temp and
A gas at
100 K and
0.5 atm will
behave most
like ideal gas
than when it
is at 50 K
and 1 atm
Low Pressure
Behave Least Like
under: Low Temp and
High Pressure
37. Factors that affect
gas behaviors
38. Pressure units
39. Volume units
pressure, volume,
temperature
atm and kPa
1 atm = 101.5 kPa
ml, L, cm3
1 L = 1000 mL
1 ml = 1 cm3
40. Temperature units
C (Celsius) K (Kelvin)
o
K = oC + 273
.
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Topic 2/3 Matter and Energy/Gases
Key Concept
41. Volume-Pressure
relationship
(constant Temp)
Definitions and facts
Volume is inversely
proportional to pressure of
a gas
. As pressure increases,
volume decreases
42. Volume-Temperature Volume is directly
proportional to Kelvin
relationship
Temperature of a gas
(constant Pressure)
. As temperature
increases, volume
increases
43. Pressure-Temperature Pressure is directly
relationship
proportional to Kelvin
Temperature of a gas
(constant Volume)
. As Temperature
increases, pressure
increases
45. Combined Gas law
(See Table T)
P1 V1
T1
=
P2 V2
T2
(see example problem on
page 9)
6
Examples
P (atm)
T (K)
T (K)
Topic 2/3 Matter and Energy/Gases
Key Concept
Key facts and definitions
46. Physical properties
47. Chemical properties
48. Physical Change
Examples
Observe through senses Color, size, shape
without changing
Luster, ductile,
chemical compositions. malleability,
conductivity
Differences in physical
properties is used to
separate substances in
mixture
Melting Point
Freezing point
Boiling Point
Observe through
interaction with other
substances
It reacts,
It burns
It combusts
It decomposes
It combines with
State (phase)
solubility
Phase change
A change that does not H2O(l) -- > H2O(s)
change chemical
composition of a
Dissolving
substance
NaCl(s) -- > NaCl(aq)
. No new substance is
Size change
formed
. Most are reversible
49. Chemical Change
A change that changes
the chemical
composition of a
substance
. New substances are
always produced
Chemical
reactions
H2 + N2 -- > NH3
. Most are irreversible
.
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Topic 2/3 Matter and Energy/Gases
Key Concept
s
Example diagrams
50. Types of
Matter
Matter
Pure Substance
Elements
Compounds
Solid
Homogeneous Heterogeneous
•• •••••• ••
•••• •• ••
•• •• •
••••••••
•••••••
••••••••
•••••••
•••••••
51. Phases of
Matter
Mixture
particles
(atoms or
molecules)
• • ••
• •• ••• •••
• •
Liquid
Gas
Heating Curve
52. Phase
FP/MP 40oC
Change
diagrams KE
PE
FP: Freezing
Point
MP: Melting
Point
BP: Boiling
Point
KE
PE
S/L, L/G
S: Solid Phase
L: Liquid Phase
FP/MP 0oC
G: gas Phase
(evaporation)
60
50
40
30
20
10
KE
8
S/L
Time
Cooling Curve
110
(condensation)
G/L
50
(freezing)
0
L/S
-10
KE
decreases
constant
PE
(melting)
120
100
KE: Kinetic
energy
PE: Potential
energy
L/G
PE
L/S, G/L
-20
Time
Topic 2/3 Matter and Energy/Gases
Key Concept
Equations
Example Questions
53. Pressure
conversion
1 atm = 101.3 kPa What pressure, in atm, is
54. Volume
conversion
1L = 1000 mL
What volume in milliliters is
equivalent to 1.33 L?
1.33 L = 1330 mL
55. Temperature
conversion
K = 273 + oC
What temperature, in degree
Celsius is equivalent to 79 K?
equivalent to 259 kPa?
259 kPa = 2.6 atm
79 K = -194oC
How much heat is needed to
change a 2.5 g sample of water
from 38oC to 53oC?
q = (2.5) (4.18) (15) = 156.8 J
56. Heat (q) calculation q = m C
during
Temperature change
57. Heat calculation
during
Phase Change
How much heat must be
released to freeze a 18 g sample
of water at 0oC?
q = (18) (334) = 6012 J
q = m Hf
What is the heat of vaporization
of a substance if 20 g sample
requires 33,000 joules of energy
to vaporize?
q = m Hv
Hv =
33000
= 1650 J/g
20
58. Gas law
Calculations
P1V1
T1
When using combined gas
law equation, cross out
any factor that is a
constant.
P2V2
=
T1
A 50 mL sample of a gas is at
2 atm and 320 K. What will be
the new volume of the gas at
(50) (2)
Last 5 equations
are on Table T
=
320
( ) (V2)
85.3 ml = V2
.
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