Properties of Matter
Properties and Changes
Physical Properties
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Substance – matter that has a uniform and
unchanging composition (pure substance)
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Example: salt – NaCl, water – H2O
Salt water – not pure, changes w/location!
Physical properties – characteristics that
can be observed or measured without
changing the composition (includes pure
substances)
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viscosity
conductivity
malleability
hardness
melting point
boiling point
density
color
odor
Types of Physical Properties
(Activity)
1.
Extensive properties – dependent on amount
present
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2.
Mass
weight
length
volume
Intensive properties – independent of amount
present; used to identify a substance
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Density
Color
Odor
luster
malleability
ductility
conductivity
hardness
melting/freezing/boiling point
Using Physical Properties
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Identification of a material – crucial in
solving crimes
Choose a material for a specific purpose shoelaces
Separation of the substance
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magnetic properties
filtration
distillation
crystallization
chromatography
Recognizing Physical Changes
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Some of the properties of a material
change, but the substances in the material
remain the same – some are reversible
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heating butter
crumpling paper
slicing a tomato
wrinkly shirt/iron
hair braiding
peeling oranges
Chemical Properties
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Chemical properties – the ability of a
substance to combine with or change into
another substance
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Iron + O2 -> Rust (FeO2)
CO2 + H20 -> C6H12O6 + O2
EVERY SUBSTANCE HAS A UNIQUE
SET OF PHYSICAL AND CHEMICAL
PROPERTIES
Observing Chemical Properties
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Flammability – ability to burn in the
presence of oxygen
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fuels
fire starters
fabric
flame-resistance
Reactivity – how readily a substance
combines chemically with other
substances
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Oxygen – high, rust
Nitrogen - low
Recognizing Chemical Changes
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Evidence of chemical changes include:
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change in color – leaves on trees, banana
peel, copper, silver
Production of gas – vinegar and baking
soda, cake baking
Formation of a precipitate – acid + milk
(protein goes through chemical change),
cottage cheese
States of Matter
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Materials can be classified as solids,
liquids, gases, or plasma based on
whether their shapes and volumes are
definite or variable (plasma only occurs
naturally in the form as lightning bolts)
Shape and volume are clues to how the
particles within a material are arranged
Plasma
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Free electrons are released at a very high
temperature
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lightning
sun
neon signs
fire
Solids
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Definite shape and volume
Atoms are packed close together and have
an orderly arrangement of particles
Changing the container doesn’t change
the shape or volume of a solid
Examples: pencil, cafeteria tray, book,
quarter
Can you change the shape or volume of
an object that is solid?
Liquids
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Definite volume and take the shape of its
container
Can be poured, will take on a new shape
Atoms are close together, but their
arrangement is more random than those
of a solid
Examples: juice, water, mercury, honey
Gases
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Does not have a definite shape nor a definite
volume
Takes the shape and volume of its container
Atoms are not arranged in a regular pattern and
can have a big space between them
Vapor – refers to the gaseous form of a
substance that is a solid or liquid at room temp.
COMPRESSIBLE
Examples: Air, helium, natural gas
How well did you listen?…
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A vapor and a gas are the same thing.
A liquid conforms to its container.
Particles of a gas are spaced closer
together than particles of a liquid.
A solid has a definite shape but
changeable volume.
Chemical Equations
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A useful description of a chemical reaction
tells you the substances present before
and after the reaction
Reactants undergo the change and the
new substances that are formed are the
products
Reactants -> Products
Conservation of Mass
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The law of conservation of mass states
that mass is neither created nor destroyed
Piece of charcoal burns, gets smaller until
it is a tiny pile of ash; charcoal is being
converted into gaseous products
Mass of the products equal the mass of
the charcoal and the oxygen reacted
Conservation of Mass
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In order to show that mass is conserved
during a reaction, a chemical equation
must be balanced using coefficients –
numbers that appear before the formulas
Mass of reactants = Mass of products
2 H2 + O2 -> 2 H2O
4 g + 32g ->
36 g
Practice!
1. If 50 grams of sodium reacts with chlorine to
form 126 grams of salt. How many grams of
chlorine reacted?
2. If 20 grams of aluminum reacts with 200
grams of bromide to form aluminum bromide,
and no aluminum is left after the reaction, but
23 grams of bromine remained unreacted.
How any grams of aluminum bromide were
formed?
Practice!
3. If 178.8 g of water is separated into hydrogen
and oxygen gas, and the hydrogen gas has a
mass of 20.0 g. What is the mass of the
oxygen gas produced?
4. From a laboratory process, a student collects
28.0 g of hydrogen and 224.0 g of oxygen.
How much water was originally involved in the
process?
Practice!
5. A student carefully placed 23.0 g of sodium in a
reactor with an excess quantity of chlorine gas.
When the reaction is complete, the student
obtained 58 grams of salt. How many grams of
sodium reacted?
6. A 10 gram sample of iron reacts with oxygen to
form 18.2 grams of ferric oxide. How many
grams of oxygen reacted?
Practice!
7. From a laboratory experiment designed to
separate water into hydrogen and oxygen gas,
a student collected 10.0 g of hydrogen and
79.4 g of oxygen. How much water was
initially involved in the process?
8. A student carefully placed 15.6 g of sodium in
a reactor supplied with an excess quantity of
chlorine gas. When the reaction was complete,
the student obtained 39.7 g of sodium
chloride. How many grams of chlorine gas
reacted?
Practice!
9. In a flask, 10.3 g of aluminum reacted with 100
g of liquid bromine to form aluminum bromide.
After the reaction, no aluminum remained, and
8.5 grams of bromine remained unreacted.
How many grams of compound were formed?
10. A 10.0 g sample of magnesium reacts with
oxygen to form 16.6 g of magnesium oxide.
How many grams of oxygen reacted?