Transcript Honors Chapter 2

Honors Chemistry
Chapter 2
Matter and Change
• Matter – anything that has mass and
takes up space
• Mass- amount of matter an object
contains
• Materials – differ in type of matter they
are composed of
The Properties of Matter
• Extensive properties – depend on the
amount of matter that is present
– Example – volume, mass, amount of energy
in the substance
• Intensive properties – do not depend on
the amount of matter that is present
– Example – melting point, boiling point, density
• Substance – matter that is uniform and
has a definite composition
– All samples of an identical substance have
the identical physical and chemical
properties
Physical property – quality or condition of a
substance that can be observed or measured
without changing the substance’s
composition
Properties of Matter
When a substance undergoes a physical change, its
physical appearance changes.
Ice melts: a solid is converted into a liquid.
Physical changes DO NOT result in a change of
composition.
Examples of Physical Properties
 Color
 Odor
 Hardness
 Density
 Solubility
 Melting
point, boiling point, freezing
point
 Physical state – solid, liquid, gas
• Page 40 Table 2.1 Physical
properties of some substances
States of matter
•
•
•
•
Solid (s)
Liquid (l)
Gas
(g)
Plasma – we don’t deal with
Classification of Matter
States of Matter
Matter can be a gas, a liquid, or a
solid.
Gases have no fixed shape or
volume.
Gases can be compressed to
form liquids.
Liquids have no shape, but they
do have a volume.
Solids are rigid and have a
definite shape and volume.
Gas and vapor not the same
Gas – normally exists that way at
room temperature
Vapor – gas state of a substance that
is normally a liquid or solid at room
temperature
Physical change
• A change which alters a
material without changing its
composition
• Cutting, grinding, melting,
boiling, freezing, dissolving
Mixtures
Physical blend of two or more
substances
Composition can vary
2 types:
Heterogeneous
Homogeneous
Heterogeneous Mixture
Not uniform in composition
Has 2 or more phases
Phase – any part of a system
with uniform composition and
properties
Dirt, salad, paper, rocky road
ice cream
Homogeneous Mixture
 Has
a completely uniform
composition
 All components are evenly
distributed
 Consists of a single phase
 Called a SOLUTION
Solution – what do you think of?
• Can be gas, liquid, or solid!!!!!
Separating mixtures
Use PHYSICAL methods
 Magnet, sifting,
 Liquid mixtures – distillation
Page 47

Page 47 #11-17
Substances
Can be elements or compounds
 Element – definition
 Compound – 2 or more elements that
have been CHEMICALLY combined.
 Can only be separated by CHEMICAL
means
• Sugar + heat carbon + water
• Water + electric current  hydrogen +
oxygen
Properties of compounds

MUCH DIFFERENT THAN THE
PROPERTIES OF THE ELEMENTS
FROM WHICH THEY ARE
COMPOSED!!!!!

NaCl
Matter
substance
element
mixture
compound
heterogeneous
homogeneous

Flow chart – Pg. 50

Elements  represented by symbols


Compounds  represented by
formulas
Pg. 52 Table 2.2
Chemical Change

A change that produces matter with a
different composition than the original
matter
Properties of Matter
When a substance changes its composition, it undergoes a
chemical change:
When pure hydrogen and pure oxygen react completely, they
form pure water.
Is iron transforming into rust a
physical or chemical change
A.
B.
Physical
Chemical
Does the substance change composition or just change appearance?
The color of sulfur is yellow..
A.
B.
Physical
Chemical
Does the substance change composition or just change appearance?
Dynamite explodes to form a
mixture of gases
A.
B.
Physical
Chemical
Does the substance change composition or just change appearance?
Aluminum melts at 933 K
A.
B.
Physical
Chemical
Does the substance change composition or just change appearance?
Plants use CO2 to make sugar
A.
B.
Physical
Chemical
Does the substance change composition or just change appearance?
Chemical Reactions



One or more substances change
into new substances
REACTANT(S)  PRODUCT(S)
 means “change into”, “produce”,
“yields”
Chemical Property
• The ability of a substance to
undergo chemical reactions and to
form new substances
• Rusting, burning, fermenting,
exploding, rotting, decomposing
• Iron and sulfur example
Indications that a
chemical reaction has
occurred
• Energy released or absorbed
• Color change
• Odor released
• Production of a gas
• irreversibility
Law of Conservation of
Mass
• During any chemical reaction,
the mass of the products is
always equal to the mass of the
reactants.