Chapter 3 - MATTER-PROPERTIES AND CHANGES
Definitions of Properties
Physical properties can be SEEN without CHANGING
matter.
Chemical properties describe how a SUBSTANCE
REACTS with other SUBSTANCES.
Examples of Properties
Physical properties
Chemical properties
MALLEABILITY
REACTIVITY
DENSITY
COMBUSTIBILITY
COLOR
FLAMMABILITY
SOLUBILITY
ACIDITY
MASS
Phases of Matter
Solids - DEFINITE shape & DEFINITE volume
particles PACKED TOGETHER
Liquids - INDEFINITE shape & DEFINITE volume
particles have ROOM to MOVE
Gases - INDEFINITE shape & INDEFINITE volume
particles FAR APART
Types of Changes
Physical change -NO CHANGE in IDENTITY of substance
Chemical change-ONE or more NEW substances produced
Phase changes are PHYSICAL CHANGES.
Freezing point— LIQUID to SOLID
Melting point— SOLID to LIQUID
FREEZING point = MELTING point
Boiling point— LIQUID to GAS
Condensation point— GAS to LIQUID
Sublimation point— SOLID to GAS
Examples of Changes
Physical Changes
Chemical Changes
TEARING
COMBUSTION
CRUSHING
PRODUCTION OF ACID RAIN
PHASE CHANGE
SUBLIMATION
Law of Conservation of Mass—Mass CANNOT be
CREATED OR DESTROYED.
The Chemistry Quiz
CR1.C CR2.D 1.C
2.A
3.D
4.C
5.B
Physical Properties
INTENSIVE properties depend upon the nature of the substance
and are INDEPENDENT of the amount of matter present.
Examples are COLOR, DENSITY, MELTING POINT, and
FREEZING POINT
EXTENSIVE properties describe only the amount of material.
Examples are LENGTH, VOLUME, MASS, AREA
MALLEABLE means the substance (metal) can be hammered
into thin sheets.
DUCTILE means the substance (metal) can be pulled into thin
wire.
Separating by physical means
DISTILLATION is a physical change that uses boiling point
differences to separate a mixture (usually liquids).
PETROLEUM is separated into its components
FRACTIONATION column.
using a
http://www.wwnorton.com/chemistry/tutorials/ch12.htm
EVAPORATION is a physical change from a
liquid to
a gas.
In DISSOLVING the solute seems to disappear but has actually
broken down into pieces too small to be seen.
CRYSTALLIZATION is a separation technique that results in
the formation of pure solid particles of a substance from a
solution containing the dissolved substance. The solid that
comes out of solution is called a PRECIPITATE.
CHROMATOGRAPHY is 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).
http://antoine.frostburg.edu/chem/senese/101/matter/chromatography.shtml
http://www.rpi.edu/dept/chem-eng/Biotech-Environ/CHROMO/chroanim.html
FILTRATION- the techniques that uses a porous barrier to
separate a solid from a mixture.
Chemical changes (reactions)
In a CHEMICAL change a new
with different properties is formed.
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Some signs of a chemical change are:
1. A COLOR change.
substance
2. A ENERGY change.(HOT, COLD, LIGHT)
3. The formation of a PRECIPITATE.
(substance that CRYSTALLIZES out of solution)
4. The formation of BUBBLES. (GAS produced)
ELECTROLYSIS is a chemical change that uses
electricity to separate a compound into its elements.
Water can be separated into OXYGEN and HYDROGEN by
electrolysis.
In a CHEMICAL REACTION one or more substances CHANGE
into one or more DIFFERENT substances.
The starting substances are called REACTANTS. The new
substances are called PRODUCTS.
When an iron and sulfur mixture is heated it turns into iron
sulfide. The reactants are IRON AND SULFUR and the product
is IRON SULFIDE.
The reaction can be written as
iron + sulfur
 iron sulfide
REACTANTS
PRODUCT
Fe + S
 FeS
In a chemical reaction the mass is always CONSERVED. The
mass of the REACTANTS will equal the mass of the
PRODUCTS.
This is known as the Law of the CONSERVATION of MASS.
The Law is attributed to the French scientist ANTOINE
LAVOISIER.
When mercury(II) oxide is heated in air it decomposes into
mercury and oxygen. The sum of the masses of the products
EQUALS the sum of the masses of the reactants. The word
equation is:
MERCURY OXIDE MERCURY + OXYGEN
216 g
=
200 g
+ 16 g
Mass of REACTANTS = mass of PRODUCTS
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The Law of Conservation of Mass has been changed slightly to
account for changes between MASS and ENERGY.
Law of CONSERVATION of MASS and ENERGY mass and
energy-The sum of the energy and mass is CONSTANT
E = mc2
(c = 3 x 108 m/s)
Energy can change into MASS
and mass can change into
ENERGY but the total massenergy is CONSTANT.
Types of Matter
Element - PURE substance
- ONE kind of ATOM
ONE or MORE letter symbol
HELIUM (He) 90 elements occur naturally
Compound - TWO or more ELEMENTS CHEMICALLY combined
-represented by CHEMICAL FORMULA
- example: WATER (H2O)
-H2O DECOMPOSES into HYDROGEN GAS and OXYGEN GAS.
-COMBINES in same PROPORTION
Episode 202
Mixture - TWO or more substances PHYSICALLY COMBINED
do not COMBINE in same PROPORTION
heterogeneous mixture - not UNIFORM
homogeneous mixture (solution) - UNIFORM
alloy - SOLUTION of two or more METALS
Pure SUBSTANCES are HOMOGENEOUS.
Matter
PURE SUBSTANCE
ELEMENT
MIXTURE
HETEROGENEOUS
COMPOUND
HOMOGENEOUS
E = element S = homogeneous mixture/solution
C = compound HE = heterogeneous mixture
hydrogen peroxide C
carbon E
carbon dioxide C
carbon monoxide C
pizza HE steel S
salad dressing
HE
calcium E
rust C
lead E
apple juice S
The Chemistry Quiz
CR1._____ CR2._____ 1._____ 2._____3._____ 4._____ 5._____
CHARACTERISTICS OF SOLUTIONS (homogeneous)
The part of the solution that is dissolved is called the SOLUTE. The
SOLVENT is the part of the solution that does the dissolving.
s
o
l
solute
e
n
t
Characteristics of solutions
1. Do NOT SCATTER (DIFFUSE) light.
2. Do NOT SETTLE on standing. (suspensions do – muddy
water)
3. UNIFORM throughout. (homogeneous)
4. Particles too SMALL to be seen even under an ordinary
MICROSCOPE. (atoms, ions or molecules)
5. VARIABLE composition. (they’re mixtures)
6. Could be made of GASES, SOLIDS OR LIQUIDS. (any
combination)
7. Can NOT be separated by FILTRATION. (see #4 above)
ALLOYS are metal solutions.
Ex. BRASS, BRONZE, STEEL
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MATTER
HOMOGENEOUS
Uniform
SUBSTANCE
Definite
composition
ELEMENT
1 kind of
atom
HETEROGENEOUS
Variable
HOMOGENOUS
MIXTURE
Variable
composition
1 phase
HETEROGENEOUS
MIXTURE
Variable
composition
More than 1 phase
aka
SOLUTION
Uniform
COMPOUND
Can be
chemically
broken down
to elements
More than 1 kind of ATOM
Separating Mixtures
The components of a mixture may be separated based on the
physical properties of:
MAGNETISM
DENSITY (An instrument that uses this property to separate
mixtures when tiny solid particles are dissolved in a liquid is
called a CENTRIFUGE.)
Some techniques used to separate the components of a mixture
are:
FILTRATION-used to separate liquids and solids
EVAPORATION of solvent, solute remains (eg. Salt crystallizes)
DISTILLATION using differences in boiling points to separate
liquids
Observation
Explanation
1.ice cube on left floated ice - less dense than liquid
ice cube on right sank -ice more dense than liquid2.
Episode 203
2. Egg sank on the left
Egg floated on the right
3. Regular soda sank
Diet soda floated
-more dense than liquid
-less dense than liquid
-more dense than water
-less dense than water
Review: The Law of the CONSERVATION of MASS. In a
chemical reaction the mass is always CONSERVED. The
sum of the masses of the REACTANTS EQUALS the sum
of the masses of the PRODUCTS. Use for HW #50-53 p94
Ex #1. From a laboratory process 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 originally
involved in the process ?
massreactants = mass products
water

hydrogen + oxygen
masswater
= masshydrogen + massoxygen
masswater = 10.0 g + 79.4 g
masswater = 89.4 g
Ex #2. 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?
massreactants =
masssodium + masschlorine =
mass
products
masssodium chloride
The Law of Definite Proportion & Percent by Mass
The LAW of DEFINITE PROPORTIONS states that a compound
is always composed of the same elements in the same
proportion by mass. The percentage by mass of each element in
a compound is always the SAME.
% by mass = mass of ELEMENT
X 100
mass of COMPOUND
The mass of the compound = the SUM of the MASSES of its
ELEMENTS
Ex #1. Magnesium combines with oxygen to form magnesium
oxide. If 10.57 g of magnesium reacts completely with 6.96 g
of oxygen, what is the percent by mass of oxygen in
magnesium oxide?
1. Write out word equation
mass magnesium + mass oxygen = mass magnesium oxide
2. Plug in values to get mass of compound
10.57 g + 6.96 g = mass magnesium oxide = 17.53 g
3. solve for percent by mass
percentoxygen by mass = (mass oxygen/mass magnesium oxide) X 100
= 6.96 g
x 100 = 39.7%
17.53 g
The Law of Multiple Proportions
The LAW of MULTIPLE PROPORTIONS states that when
different compounds are formed by combination of the same
elements, different masses of one element combine with the
same relative mass of the other element in a small whole
number ratio.
Copper and chlorine combine to make two different compounds
with different properties.
Compoun %Cu
%Cl
Mass of
Mass of
Mass ratio
d
I
64.20
35.80
II
47.27
52.73
1.793 g = 2.00 2:1
0.896 g
1
Cu in 100
g of
compoun
d
Cl in 100 mass Cu
g of
mass Cl
compoun
d
64.20g
35.80g
35.80g
35.80g
1.793g Cu
1 g Cl
47.27g
52.73g
0.896g Cu
1 g Cl
52.73g
52.73g
A small-whole number ratio
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