Transcript Test 3 - Chapter 3 Matter – Properties and Changes

Chemistry Fall 2009
Everything around you is matter.
Matter that has a uniform and unchanging
composition is called a substance, or pure
substance.
 Examples of pure substances: table salt, and
distilled water.
 Is seawater a substance?
 Every substance has its own unique set of
physical and chemical properties.
 Observations of properties may depend on the
conditions of the immediate environment.
(Temperature and Pressure)
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characteristics that can be measured or
observed without changing the sample’s
composition.
Examples: shape, color, or weight.
Can be used to describe substances – density,
color, odor, taste, hardness, melting point,
and boiling point provide an identifying
characteristic of a substance.
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Extensive – dependent on the amount of
substance present
 Mass, length, or volume
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Intensive – independent of the amount of
substance present
 Density
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the ability or inability of a substance to combine
with or change into one or more other
substances
Usually not obvious until the substance has
changed or not changed composition as a result
of:
 Contact with another substance
 The application of thermal energy
 The application of electrical energy
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Example: the ability of iron to rust when
combined with air, but not when combined with
nitrogen gas.
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3 common physical forms – solid, liquid, and
gas
4th state is plasma – it is a gas-like mixture of
charged particles found in stars, and
lightening bolts.
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form of matter that has a definite shape and
a definite volume
Examples: wood, iron, paper, and sugar
Particles are very tightly packed,
incompressible
Not dependent on rigidity or hardness
Expands slightly when heated
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form of matter that flows, has a definite
volume, but takes the shape of its container
Examples: water, blood, and mercury
Particles are not held rigidly in place and are
less closely packed than the particles in a
solid. The particles are able to move past one
another.
Liquids are virtually incompressible.
Expand when heated
a form of matter that flows to conform to the
shape and volume of its container
 Examples: neon, methane, and air
 Particles are very far apart, easily compressed
 The words gas and vapor do not mean the same
thing.
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 Gas – refers to a substance that is in the gaseous state
at room temperature.
 Vapor – refers to a gaseous state of a substance that
is a solid or liquid at room temperature.
▪ Example - steam
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Textbook p.60 (1-3, 5) – Write the questions
and answers on a sheet of loose-leaf paper to
be turned in at the end of the chapter.
Workbook p. 13-14
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Two types of changes that matter can
undergo:
 Physical
 Chemical
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a change that alters a substance without changing its
composition. (Appearance may change, but identity
remains the same.)
Examples: crumpling a sheet of aluminum foil, cutting
a sheet of paper, and breaking a crystal
Verbs used to indicate physical changes: bend, grind,
crumple, split, crush, and cut
Changes in state/phase are also physical changes.
(Appearance changes, but identity remains the same.)
Ex. Ice to water to steam – all are H2O
Verbs indicating a change in phase: boil, freeze,
condense, vaporize, or melt
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the process that involves one or more substances
changing into new substances (AKA chemical
reaction)
The new substances formed have different
compositions and properties from the previous
substances.
Examples: the fermentation of grape juice, sugars, etc
to wine; iron and oxygen forming rust
In chemical reactions, the starting substances are
called reactants and the newly formed substances are
called products.
Verbs referring to chemical reactions (rxns): explode,
rust, oxidize, corrode, tarnish, ferment, burn, or rot
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states that mass is neither created nor
destroyed during a chemical rxn –it is
conserved. (Antoine Lavoisier – late 18th
century)
Massreactants = Massproducts
Example:
Mercury (II) oxide yields mercury + oxygen
216 g
200g + 16g
Mass of reactant = mass of products
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In your notes – complete practice problems 69 on p. 65.
On your loose-leaf paper for the chapter,
write and answer questions 10-12, 14 on p.65.
Workbook p.15
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A mixture is a combination of two or more
pure substances in which each pure
substance retains its individual properties.
The composition of mixtures is variable.
Most everyday examples of matter occur as
mixtures.
Examples – sodas, salad, sugar water, air,
vinegar, steel, etc.
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Heterogeneous – one that does not blend
smoothly throughout and in which the
individual substances remain distinct.
Examples – sand and water, pizza, Italian
salad dressing
The existence of two or more unique areas
indicates a heterogeneous mixture.
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It is a mixture that has a constant
composition throughout and it always has a
single phase.
Also referred to as solutions
Examples – salt water, steel, cough medicine
An alloy is a homogeneous mixture of metals,
or a metal and a nonmetal in which metal is
the primary component.
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Most matter exists naturally as mixtures.
Because mixtures are physically combined,
we must use physical processes to separate
them.
These processes are based on the differences
in physical properties of the substances in the
mixture.
Examples – magnetism, filtration, distillation,
crystallization, chromatography
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A technique that uses a porous barrier to
separate a heterogeneous mixture of a solid
and a liquid.
Examples – filter paper, a colander, or a
strainer
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A separation technique that uses the
differences in boiling points of the substances
involved in a homogeneous mixture.
A mixture is heated until the substance with
the lowest boiling point boils to a vapor that
can then be condensed into a liquid and
collected.
When precisely controlled, distillation can
separate substances having boiling points
that differ by only a few degrees.
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A separation technique that results in the
formation of pure solid particles of a
substance from a solution containing the
dissolved substance.
It produces highly pure substances.
Examples – Rock Candy
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A technique that separates the components
of a mixture (called the mobile phase) on the
basis of the tendency of each to travel or be
drawn across the surface of another material
(called the stationary phase).
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With a partner, complete the miniLab on
p.68.
On a sheet of loose-leaf paper, copy the title,
materials, procedures, and analysis sections.
Answer the analysis questions and turn in
your lab for credit.
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On your loose-leaf sheet for the chapter,
write and answer questions 15-19 on p.69.
Workbook p.16
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The classification of pure substances – two
categories:
 elements
 compounds
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a pure substance that cannot be separated
into simpler substances b physical or
chemical means; the basic building block of
matter
91 elements occur naturally on Earth
each has a unique name and symbol
symbols – one, two, or three letters; the 1st
letter is always capitalized and the remaining
letter(s) are always lowercase
Ex. Copper, Oxygen, Gold
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organizes elements into a grid of horizontal
rows called periods and vertical columns
called groups or families.
Elements in the same group have similar
properties.
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a combination of two or more different
elements that are combined chemically.
Ex. Water, table salt, table sugar, aspirin
Approximately 10 million known compounds
with new ones being discovered/developed at
a rate of about 100,000 per year
Formulas are written using the chemical
symbols for the elements within the
compound.
Can be separated by chemical means
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Properties are different from those of its
component elements
Ex –
 Hydrogen – tasteless, odorless gas
 Oxygen - tasteless, odorless gas
 Water – clear liquid at room temp.
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Ex –
 Sodium – highly reactive metal that fizzes and burn in
water
 Chlorine – poisonous, pale green gas
 Sodium Chloride – white, unreactive solid that we use
to flavor foods (SALT)
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states that, regardless of amount, a
compound is always composed of the same
elements in the same proportion by mass.
This law is used to find the formulas for
compounds.
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(mass of element / mass of compound) x 100
Complete practice problems 20-24 on page
76 in your notes.
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On your loose-leaf page for the chapter, write
and answer questions 25-30 on p.77.
Workbook p.17-18
Review the Study Guide Summary on p.81.
Make sure that you have all equations and
vocabulary terms in your notes.
A study guide for this chapter has been
placed on the class website. Complete it and
turn it in on test day for extra stamps.
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The test will be Thursday, September3, 2009.
It will consist of 35 multiple-choice questions,
and 4 problems.
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states that when different compounds are
formed by a combination of the same
elements, different masses of one element
combine with the same relative mass of the
other element in a ration of small whole
numbers.