Transcript V. Physical Behavior of Matter

V. Physical Behavior of
Matter
Matter is classified as a pure
substance or as a mixture of
substances. (3.1q)
Substances
Elements
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Diatomic
Elements
Mixtures
Compounds
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A pure substance (element or
compound) has a constant
composition and constant
properties throughout a given
sample, and from sample to
sample. (3.1r)
All substances are homogeneous.
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Elements are substances that
are composed of atoms that
have the same atomic number.
Elements cannot be broken
down by chemical change. (3.1u)
There are more than 100 different elements
Elements are represented by chemical symbols
The first letter of the symbol is always a capital letter the rest
are lower case
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Nitrogen
Neon
A temporary symbol
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Some elements are diatomic.
They come in pairs when not
combined with other
elements.
 Diatomic Elements
–
–
–
–
–
–
–
Hydrogen
Oxygen
Nitrogen
Chlorine
Bromine
Iodine
Fluorine
Br2 I2 N2 Cl2 H2 O2 F2
Neon is a monatomic element
Nitrogen is a diatomic element
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Compounds are substances that are
composed of two or more different
elements chemically combined.
 The elements in a compound are in fixed
proportions
 A compound can only be decomposed by
chemical means
 Compounds are represented by chemical
formulas
 Compounds are electrically
neutral
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Using particle diagrams to
represent elements, compounds
and mixtures.
Compound
Mixture
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Element
Diatomic
element
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Regents Question: 08/02 #6
Which species represents a chemical compound?
(1) N2
(3) Na
(2) NH4+
(4) NaHCO3
Compounds are made up of more
than one type of element. (Look
for more than one capital letter.)
Compounds are electrically neutral.
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Regents Question: 06/03 #9
Which substance can be decomposed by a chemical
change?
(1) Co
(2) CO
(3) Cr
(4) Cu
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Mixtures are composed of two
or more different substances
that can be separated by
physical means.
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Regents Question: 06/02 #43
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Regents Question: 08/02 #51
On a field trip, Student X and Student Y collected two rock
samples. Analysis revealed that both rocks contained
lead and sulfur. One rock contained a certain percentage
of lead and sulfur by mass, and the other rock contained
a different percentage of lead and sulfur by mass.
Student X stated that the rocks contained two different
mixtures of lead and sulfur. Student Y stated that the
rocks contained two different compounds of lead and
sulfur. Their teacher stated that both students could be
correct.
Draw particle diagrams in each of the rock diagrams
provided in your answer booklet to show how Student X’s
and Student Y’s explanations could both be correct.
Use the symbols in the key provided in your
answer booklet to sketch lead and sulfur atoms.
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Regents Question: 08/02 #51
Answer
Draw particle diagrams in each of the rock diagrams
provided in your answer booklet to show how Student
X’s and Student Y’s explanations could both be
correct. Use the symbols in the key provided in your
answer booklet to sketch lead and sulfur atoms.
Student X
Student Y
Rock A
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Rock B
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When different substances are
mixed together, a homogeneous
or heterogeneous mixture is
formed. (3.1s)
A homogeneous mixture is called a solution
A solution in which something is dissolved in water is
called an aqueous solution
NaCl(aq) means that sodium chloride (table salt) is
dissolved in water and is therefore a homogenous
mixture. (aq) stands for aqueous
An alloy is a solution of metals eg. brass, bronze
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Regents Question: 06/03 #15
Which of these terms refers to matter that could be
heterogeneous?
(1) element
(2) mixture
(3) compound
(4) solution
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The proportions of
components in a mixture can
be varied. Each component in
a mixture retains its original
properties. (3.1t)
Two mixtures of Hydrogen (H2) and Neon (Ne)
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Differences in properties such
as density, particle size,
molecular polarity, boiling point
and freezing point, and
solubility permit physical
separation of the components
of the mixture. (3.1nn)
Density and polarity
Particle Size
solubility
Chromatography, Filtration, Dissolving,
Distillation, Crystallization
Boiling Point
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Freezing Point
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Regents Question: 01/04 #12
A bottle of rubbing alcohol contains both 2-propanol
and water. These liquids can be separated by the
process of distillation because the 2-propanol
and water
(1) have combined chemically and retain their
different boiling points
(2) have combined chemically and have the same
boiling point
(3) have combined physically and retain the different
boiling points
(4) have combined physically and have the same
boiling point
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Density
and
polarity
Particle size
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Boiling point
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A solution is a homogeneous
mixture of a solute dissolved in a
solvent. The solubility of a solute
in a given amount of solvent is
dependent on the temperature,
the pressure, and the chemical
natures of the solute and solvent.
(3.1oo)
Dissolved particles are too small to be trapped by a filter
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Regents Question: 08/02 #7
Which mixture can be separated by using the
equipment shown?
(1) NaCl(aq) and SiO2(s)
(2) NaCl(aq) and C6H12O6(aq)
(3) CO2(aq) and NaCl(aq)
(4) CO2(aq) and C6H12O6(aq)
(aq) stands for aqueous which
means dissolved in water.
Dissolved particles are too small
to be trapped by the filter.
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Solubility of a nonvolatile solute
depends on temperature.
 Solubility is the maximum amount of solute that a
solvent can hold at a given temperature.
– An unsaturated solution is one in which the solvent
can dissolve more solute
– A saturated solution is one in which the solvent has as
much solute as it can hold
– A supersaturated solution is one in which there is
more solute dissolved than a solvent can normally hold.
• Make a supersaturated solution by cooling a saturated solution
• Supersaturated solutions are unstable and will precipitate the
excess solute when a seed crystal is added.
 As temperature increases, solubility of a solid
increases.
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Table G shows the
solubilities of some
gases and some
solids at various
temperatures when
dissolved in 100
grams of water.
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•A solution which
is on the line is
saturated
•A solution below
the line is
unsaturated
•A solution above
the line is
supersaturated
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Add a test crystal to see if a
solution is unsaturated, saturated
or supersaturated.
 Unsaturated – the test crystal dissolves
 Saturated – the test crystal settles to the
bottom
 Supersaturated – a large amount of crystals
precipitate from the solution
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Regents Question: 06/02 #40
According to Reference Table G,
which solution is saturated at
30°C?
(1) 12 grams of KClO3 in 100
grams of water
(2) 12 grams of KClO3 in 200
grams of water
(3) 30 grams of NaCl in 100
grams of water
(4) 30 grams of NaCl in 200
grams of water
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The solubility of a gas depends
on temperature and pressure.
 As temperature increases, the solubility of a
gas decreases
 As pressure increases, the solubility of a gas
increases
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Which are gases?
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Regents Question: 08/02 #48
One hundred grams of water is saturated with NH4Cl
at 50°C. According to Table G, if the temperature
is lowered to 10°C, what is the total amount of
NH4Cl that will precipitate?
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(1) 5.0 g
(3) 30. g
(2) 17 g
(4) 50. g
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Regents Question: 01/03 #65-66
When cola, a type of soda pop, is manufactured, CO2
(g) is dissolved in it.
A capped bottle of cola contains CO2 (g) under high
pressure. When the cap is removed, how does
pressure affect the solubility of the dissolved CO2
(g)?
As the pressure decreases, the solubility decreases.
A glass of cold cola is left to stand 5 minutes at room
temperature. How does temperature affect the
solubility of the CO2 (g)?
As the temperature increases, the solubility decreases.
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Oil and water are not miscible
 Like dissolves like (charged
solutes dissolve in charged
solvents, uncharged solutes
dissolve in uncharged
solvents)
(Nonpolar)
(Polar)
– Nonpolar solutes dissolve in
nonpolar solvents
– Polar solutes dissolve in polar
solvents
– Ionic solutes dissolve in polar
solvents
Dry cleaners use a nonpolar solvent to get rid of oil and grease
Liquids that dissolve each other are called miscible liquids.
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Regents Question: 06/03 #42
Hexane (C 6 H 14 ) and water do not form a solution.
Which statement explains this phenomenon?
(1) Hexane is polar and water is nonpolar.
(2) Hexane is ionic and water is polar.
(3) Hexane is nonpolar and water is polar.
(4) Hexane is nonpolar and water is ionic.
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Solubility Guidelines
 Not all substances are soluble in water
 Reference Table F lists solubility rules and
exceptions to those rules.
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Soluble
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Not Soluble
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Regents Question: 08/02 #40
Which of the following compounds is least soluble
in water?
(1) copper (II) chloride
(2) aluminum acetate
(3) iron (III) hydroxide
(4) potassium sulfate
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Regents Question: 06/03 #14
According to Table F, which of these salts is least
soluble in water?
(1) LiCl
(2) RbCl
(3) FeCl2
(4) PbCl2
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The concentration of a solution
may be expressed as molarity
(M), percent by volume, percent
by mass, or parts per million
(ppm). (3.1pp)
Molarity
Percent by mass
Parts per Million
M = moles solute
% = grams solute x 100
ppm = grams solute x 1,000,000
Liters solution
Grams solution
Grams solution
Percent by volume
% = liters solute x 100
Liters solution
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Regents Question: 06/02 #42
What is the molarity of a solution that contains 0.50
mole of NaOH in 0.50 liter of solution?
(1) 1.0 M
(3) 0.25 M
(2) 2.0 M
(4) 0.50 M
Moles
Molarity =
Liters
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Regents Question: 08/02 #36
How many moles of solute are contained in 200
milliliters of a 1 M solution?
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(1) 1
(3) 0.8
(2) 0.2
(4) 200
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Regents Question: 08/02 #49
What is the total number of grams of NaI(s)
needed to make 1.0 liter of a 0.010 M solution?
(1) 0.015
(2) 0.15
Molarity = moles
liters
0.010M = x
1.0 L
X = 0.010 moles
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(3) 1.5
(4) 15
Na 1 x 23.0 = 23.0
I
1 x 126.9 = 126.9
149.9 g / mole
0.010 moles x 149.9 g/mole =
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Regents Question: 01/03 #40
Solubility data for four different salts in water at
60°C are shown in the table below. Which salt
is most soluble at 60°C?
(1) A
(2) B
(3) C
(4) D
Salt Solubility in Water at 60 °C
A - 10 grams /50 grams H2O
B - 20 grams /60 grams H2O
C - 30 grams /120 grams H2O
D - 40 grams/80 grams H2O
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Regents Question: 01/04 #56-58
A student uses 200 grams of water at a temperature
of 60°C to prepare a saturated solution of
potassium chloride, KCl.
Identify the solute in this solution.
KCl
According to Reference Table G, how many grams of KCl must
be used to create this saturated solution?
Hint: 200 g of water was used – table G is for 100 g of water 90 g
This solution is cooled to 10°C and the excess KCl precipitates
(settles out). The resulting solution is saturated at 10°C.
How many grams of KCl precipitated out of the original
solution? 30 g
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The addition of a nonvolatile solute
to a solvent causes the boiling point
of the solvent to increase and the
freezing point of the solvent to
decrease. The greater the
concentration of particles, the
greater the effect. (3.1qq)
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Solute
Moles of particles per mole of solute
C6H12O6
1 (Non-electrolytes do not separate into ions)
NaCl
2 (1-Na+ and 1 Cl-)
CaF2
3 (1-Ca2+ and 2 F-)
H2SO4
3 (2-H+ and 1 SO42-)
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Regents Question: 06/03 #23
At standard pressure when NaCl is added to
water, the solution will have a
(1) higher freezing point and a lower boiling
point than water
(2) higher freezing point and a higher boiling
point than water
(3) lower freezing point and a higher boiling
point than water
(4) lower freezing point and a lower boiling point
than water
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The three phases of matter
(solids, liquids, and gases)
have different properties.
(3.1kk)
Solid
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Liquid
Gas
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Properties of Solids
 Regular geometric pattern in the arrangement of
the molecules called a crystal lattice
 Molecules are close together and vibrate in place
 Molecules do not move from place to place
 Solids are not compressible
 Definite shape and definite volume
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Properties of Liquids
 Molecules can move around (fluid)
 Molecules are farther apart than in a solid
 Liquids take the shape of their container
 Not compressible
 No definite shape but do have
definite volume
The forces of attraction between the molecules are weaker
in a liquid than they are in a solid.
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Properties of Gases
 Molecules fill their container (spread out)
 Molecules are very far apart
 Molecules move in straight lines until they
hit something (another molecule or wall of
the container)
 No definite shape and
no definite volume
The forces of attraction between the molecules are very weak.
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Regents Question: 08/02 #16
Which statement correctly describes a sample of gas
confined in a sealed container?
(1) It always has a definite volume, and it takes the
shape of the container.
(2) It takes the shape and the volume of any container
in which it is confined.
(3) It has a crystalline structure.
(4) It consists of particles arranged in a regular
geometric pattern.
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Regents Question: 06/02 #12
Which 5.0-milliliter sample of NH3 will take the shape of
and completely fill a closed 100.0-milliliter container?
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(1) NH3 (s)
(3) NH3 (g)
(2) NH3 (l)
(4)NH3 (aq)
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Regents Question: 06/03 #16
In which material are the particles arranged in a
regular geometric pattern?
(1) CO2 (g)
(2) NaCl(aq)
(3) H2O(l)
(4) C12H22O11 (s)
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Energy can exist in different
forms, such as chemical,
electrical, electromagnetic,
thermal, mechanical, and
nuclear. (4.1a)
Kinetic energy – the energy of motion
Potential energy – the energy of position
(stored energy)
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The amount of thermal energy
contained in the molecules
depends on how fast they are
moving and how many
molecules there are.
 The total kinetic energy of all the molecules
combined is called thermal energy
 Thermal energy is a result of the Kinetic Energy of
the molecules’ motion (molecules are always
moving.)
 Which can melt more ice: a small cup of hot water
or a swimming pool of cold water?
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Heat is a transfer of energy
(usually thermal energy) from a
body of higher temperature to a
body of lower temperature.
Thermal energy is the energy
associated with the random
motion of atoms and molecules.
(4.2a)
The Law of Conservation of Energy states that energy can
neither be created nor destroyed.
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Heat is transferred to different
materials at different rates.
 The specific heat capacity (C) determines
the rate at which heat will be absorbed.
 The specific heat capacity for water is
4.18J/g
 The quantity of heat absorbed (Q) can be
calculated by: Q=mCT
m=mass T=change in temperature
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Temperature is a
measurement of the
average kinetic energy
of the particles in a
sample of material.
Temperature is not a
form of energy. (4.2b)
Two temperature scales used in chemistry are Celsius and Absolute
The unit of temperature in the Celsius scale is the degree (ºC)
The unit of temperature on the Absolute scale is the Kelvin (K)
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Regents Question: 06/02 #16
Which change in the temperature of a 1-gram sample of
water would cause the greatest increase in the
average kinetic energy of its molecules?
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(1) 1°C to 10°C
(3) 50°C to 60°C
(2) 10°C to 1°C
(4) 60°C to 50°C
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To convert
between
absolute and
Celsius
temperature
scales use
K=ºC+273
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Kinetic molecular theory
(KMT) for an ideal gas states
that all gas particles (3.4b):
 1. are in random, constant, straight-line
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motion.
 2. are separated by great distances relative to
their size; the volume of the gas particles is
considered negligible.
 3. have no attractive forces between them.
 4. have collisions that may result in the
transfer of energy between gas particles, but
the total energy of the system remains
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constant.
The concept of an ideal gas is
a model to explain the
behavior of gases. A real gas
is most like an ideal gas when
the real gas is at low pressure
and high temperature. (3.4a)
Molecules are far apart and
moving very fast!
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Real Gases
 Molecules do take up space
 Molecules do attract each other
 Energy is lost during collisions
 Under conditions of high temperature and
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low pressure, real gases behave more like
ideal gases
 Small molecules take up little space and
have weaker forces of attraction and are
closer to an ideal gas
 Hydrogen and helium are closest to being
ideal gases
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Kinetic molecular theory
describes the relationships of
pressure, volume, temperature,
velocity, and frequency and force
of collisions among gas
molecules. (3.4c)
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P1V1
P2V2
T1
T2
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Ideal Gas Laws
 Boyle’s Law
– Indirect Relationship
between pressure and
volume
– Temperature remains
constant
– PxV = constant
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 Charles’ law
– Direct relationship
between volume and
temperature
– Pressure remains
constant
– V/T = constant
– Temperature must be
Absolute temperature
(Kelvins)
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Graphing the gas laws
As absolute temperature increases,
pressure increases at constant volume
Pressure
Temperature
As absolute temperature increases,
volume increases at constant pressure
Volume
Temperature
As pressure increases, volume
decreases at constant temperature
Volume
Pressure
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Regents Question: 06/02 #14
Which graph shows the pressure-temperature
relationship expected for an ideal gas?
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Equal volumes of different
gases at the same
temperature and pressure
contain an equal number of
particles. (3.4e)
Avogadro’s Hypothesis
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Regents Question: 06/02 #15
At the same temperature and pressure, which
sample contains the same number of moles
of particles as 1 liter of O2 (g)?
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(1) 1 L Ne(g)
(3) 0.5 L SO2 (g)
(2) 2 L N2 (g)
(4) 1 L H2O(l)
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The concepts of kinetic and potential
energy can be used to explain
physical processes that include:
fusion (melting), solidification
(freezing), vaporization (boiling,
evaporation), condensation,
sublimation, and deposition. (4.2c)
Add energy
(endothermic)
subliming
melting
SOLID
Remove energy
(exothermic)
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boiling
LIQUID
freezing
GAS
condensing
depositing
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Regents Question: 06/03 #17
Which change is exothermic?
(1) freezing of water
(2) melting of iron
(3) vaporization of ethanol
(4) sublimation of iodine
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A change in phase is a change in
Potential Energy, not Kinetic Energy
Boiling Point
Melting Point
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Potential
energy changes
so temperature
doesn’t
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Energy and phase changes
 AB - solid warms up
(KE inc/PE constant)
 BC- solid melts (KE
constant/PE inc)
 CD – liquid warms
up (KE inc/PE
constant)
 DE- liquid boils (KE
constant/PE inc)
EF – gas warms (KE inc/PE constant)
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Regents Question: 06/02 #28
As ice melts at standard pressure, its temperature
remains at 0°C until it has completely melted. Its
potential energy
(1) decreases
(2) increases
(3) remains the same
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Regents Question: 08/02 #54
A sample of water is heated from a liquid at 40°C to a
gas at 110°C. The graph of the heating curve is
shown in your answer booklet.
a On the heating curve diagram provided in your
answer booklet, label each of the following regions:
Liquid, only
Gas, only
Phase change
Gas Only
Phase change
Liquid Only
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Regents Question: cont’d
b For section QR of the graph, state what is happening
to the water molecules as heat is added.
They move faster, their
temperature increases.
c For section RS of the graph, state what is happening
to the water molecules as heat is added.
Their intermolecular bonds
are breaking, their potential
energy is increasing.
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Regents Question: 01/02 #47
What is the melting point of this substance?
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(1) 30°C
(3) 90°C
(2) 55°C
(4) 120°C
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The quantity of energy absorbed or
released during a phase change can
be calculated using the Heat of
Fusion or Heat of Vaporization
 Melting (fusion) or freezing (solidification)
– Q=mHf where Hf is the heat of fusion
(for water: 333.6 J/g)
 Boiling (vaporization) or condensing
– Q=mHv where Hv is the heat of vaporization
(for water: 2259 J/g)
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Hf and Hv are given to Table B – m is the mass
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Regents Question: 08/02 #24
In which equation does the term “heat” represent
heat of fusion?
(1) NaCl(s) + heat  NaCl(l)
(2) NaOH(aq) + HCl(aq)  NaCl(aq) + H2O(l)+ heat
(3) H2O(l)+ heat  H2O(g)
(4) H2O(l)+ HCl(g) H3O+(aq) + Cl –(aq) + heat
Fusion refers to melting.
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Melting Point
 The temperature at which a liquid and a
solid are in equilibrium
 The melting point for ice is 0ºC
 The melting point of a substance is the same
as its freezing point
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Regents Question: 08/02 #5
Given the equation: H2O(s)
H2O(l)
At which temperature will equilibrium exist when the
atmospheric pressure is 1 atm?
(1) 0 K
(3) 273 K
(2) 100 K
(4) 373 K
K=C + 273
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Regents Question: 08/02 #18
The solid and liquid phases of water can exist in a
state of equilibrium at 1 atmosphere of pressure
and a temperature of
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(1) 0°C
(3) 273°C
(2) 100°C
(4) 373°C
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Regents Question: 06/03 #41
The freezing point of bromine is
(1) 539°C
(2) –539°C
(3) 7°C
(4) –7°C
See Table S
Melting point is the same as
freezing point
Convert K to C (K=C+273)
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A physical change results in the
rearrangement of existing
particles in a substance. A
chemical change results in the
formation of different substances
with changed properties. (3.2a)
 Physical Changes
– Changes in phase
• Melting
• Boiling
• Subliming
– Dissolving
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 Chemical Changes
– Any chemical reaction
•
•
•
•
•
Synthesis
Decomposion
Single Replacment
Double Replacement
Combustion (burning)
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Regents Question: 06/03 #18
Which type of change must occur to form a
compound?
(1) chemical
(2) physical
(3) nuclear
(4) phase
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Chemical and physical
changes can be exothermic or
endothermic. (4.1b)
 Exothermic
– Potential energy
decreases
– Releases energy
– H is negative
– Energy is on the right
2H2 + O2
PE
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2H2O + energy
 Endothermic
– Potential energy
increases
– Absorbs energy
– H is positive
– Energy is on the left
2H2O + energy
2H2 + O2
PE
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Regents Question: 06/02 #64-66
A hot pack contains chemicals that can be activated to
produce heat. A cold pack contains chemicals that feel
cold when activated.
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•
Based on energy flow, state the type of chemical
Exothermic
change that occurs in a hot pack.
•
A cold pack is placed on an injured leg. Indicate the
direction of the flow of energy between the leg and the
cold pack. From the leg to the cold pack (Hot to Cold)
•
What is the Law of Conservation of Energy? Describe
how the Law of Conservation of Energy applies to the
chemical reaction that occurs in the hot pack.
Energy cannot be created nor destroyed. It can only be changed from
one form to another. The heat produced in the hot pack was stored in
the chemical bonds.
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Regents Question: 08/02 #41
According to Table I, which potential energy diagram
best represents the reaction that forms H2O(l) from
its elements?
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Activation Energy (Ea) is the energy
needed to get a reaction started
(reach the activated complex).
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Enthalpy (H)
The heat of reaction
 H=PE products – PE reactants
 The value for H is the same in the forward and
the reverse reaction. Only the sign is changed.
 Measured in kJ (kilojoules)
 + H – Endothermic – Energy absorbed
 - H – Exothermic – Energy released
 The large the value of H, the more energy
absorbed or released
 Reference Table I gives H for many reactions
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Regents Question: 08/02 #14
Given the reaction:
CH4 (g) + 2 O2 (g)  2 H2O(g) + CO2 (g)
What is the overall result when CH4 (g) burns
according to this reaction?
(1) Energy is absorbed and H is negative.
(2) Energy is absorbed and  H is positive.
(3) Energy is released and  H is negative.
(4) Energy is released and  H is positive.
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Regents Question: 08/02 #34
According to Table I, which salt releases energy as it
dissolves?
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(1) KNO3
(3) NH4NO3
(2) LiBr
(4) NaCl
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Regents Question: 08/02 #50
Given the reaction:
2 H2 (g) + O2 (g)  2 H2O(l) + 571.6 kJ
What is the approximate H for the formation of 1
mole of H2O(l)?
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(1) –285.8 kJ
(3) –571.6 kJ
(2) +285.8 kJ
(4) +571.6 kJ
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A catalyst lowers the activation
energy to speed up a reaction
Activated Complex
With Catalyst
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Regents Question: 06/02 #55-56
Given the reaction:
A+BC
•
Does the diagram
illustrate an
exothermic or an
endothermic
reaction?
Endothermic
•State one reason, in terms of energy, to support your answer.
The potential energy of the products is higher than the reactants,
Energy is absorbed.
• On the diagram provided in your answer booklet, draw a dashed
line to indicate a potential energy curve for the reaction if a catalyst is
added.
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The structure and arrangement of
particles and their interactions
determine the physical state of a
substance at a given temperature
and pressure. (3.1jj)
Solid
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Liquid
Gas
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Intermolecular forces created by
the unequal distribution of
charge result in varying degrees
of attraction between molecules.
Hydrogen bonding is an example
of a strong intermolecular force.
(5.2m)
Dipole-Dipole attraction between
polar molecules
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Hydrogen bonds occur when
hydrogen is bonded to a small,
highly electronegative atom.
N, O and F can have
hydrogen bonds when
hydrogen is bonded to it.
Account for the unusual
properties of water:
High boiling point, surface
tension, six sided snowflake
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Physical properties of substances
can be explained in terms of
chemical bonds and
intermolecular forces.
•Ionic bonds are strong
•Hydrogen bonds are strong intermolecular forces
•Polar molecules exhibit attraction between the + and –
sides of their molecules
•Bonds between nonpolar molecules are weak. The
more protons in the molecule, the stronger these forces.
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Regents Question: 06/02 #13
The strongest forces of attraction occur between
molecules of
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(1) HCl
(3) HBr
(2) HF
(4) HI
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These properties include
conductivity, malleability,
solubility, hardness, melting
point, and boiling point. (5.2n)
 The stronger the intermolecular forces, the
higher the boiling point and melting point.
 The stronger the intermolecular forces, the
lower the vapor pressure.
– See Table H
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Table H – the vapor pressure of four
liquids at various temperatures.
As temp inc,
vapor pressure
inc.
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Regents Question: 06/03 #40
According to Reference Table H, what is the vapor
pressure of propanone at 45°C?
(1) 22 kPa
(2) 33 kPa
(3) 70. kPa
(4) 98 kPa
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A liquid will boil when its vapor
pressure equals the atmospheric
pressure.
 Raising the temperature will increase the
vapor pressure of the liquid
 Lowering the atmospheric pressure will
lower the boiling point
– On top of a high mountain, water boils at a
temperature below 100C
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Standard pressure is 101.3 kilopascals
(kPa) or 1 atmoshpere (atm)
The normal boiling
point occurs when
the atmospheric
pressure is 101.3 kPa
(standard pressure)
The normal boiling
point of ethanol is
80ºC.
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Regents Question: 08/02 #28
As the pressure on the surface of a liquid decreases,
the temperature at which the liquid will boil
(1) decreases
(2) increases
(3) remains the same
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Regents Question: 08/02 #30
As the temperature of a liquid increases, its vapor
pressure
(1) decreases
(2) increases
(3) remains the same
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Regents Question: 08/02 #44
The vapor pressure of a liquid is 0.92 atm at
60°C. The normal boiling point of the liquid
could be
(1) 35°C
(3) 55°C
(2) 45°C
(4) 65°C
The normal boiling point is the temperature at
which a liquid boils when the atmospheric pressure
is standard pressure (1 atm or 101.3 kPa)
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Regents Question: 01/03 #68
What is the vapor pressure of liquid A at 70°C? Your
answer must include correct units. 700 mm Hg
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Regents Question: 01/03 #69
At what temperature does liquid B have the same vapor
pressure as liquid A at 70°C?
Your answer must include correct units. 113°C
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Regents Question: 01/03 #70
Which liquid will evaporate more rapidly? Explain your
answer in terms of intermolecular forces.
Liquid A will evaporate more rapidly because, at any temperature, it
has the weaker intermolecular forces.
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