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## Chapter 3 Matter Properties and Changes

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### Chapter 3 Matter Properties and Changes DENSITY Density is a ratio that compares an objects mass to its volume. The unit for density is g/ L or g/ cm3. – PowerPoint PPT presentation

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Title: Chapter 3 Matter Properties and Changes

1
Chapter 3 Matter Properties and Changes
2
DENSITY
• Density is a ratio that compares an objects mass
to its volume. The unit for density is g/ L or
g/ cm3.
• A large piece of Styrofoam has the same mass as a
quarter, but the quarter has a smaller volume.
The quarter has a greater density, because there
is a greater amount of mass contained in a
smaller space.

3
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4
1. A 5-mL sample of water has a mass of 5 g. What
is the density of water?
2. An object with a mass of 7.5 g raises the level
of water in a graduated cylinder from 25.1 mL to
30.1 mL. What is the density of the object?
3. The density of aluminum is 2.7 g/mL. What is the
volume of 8.1 g?

5
Section 3.1
• Matter is anything that has mass and takes up
space.
• Matter that has a uniform and unchanging
composition is called a substance.
• Common examples of substances include salt and
water.

6
• Matter has specific properties. Properties of
matter can be physical or chemical.
• Physical properties are properties that can be
observed or measured without changing the
composition of the substance.
• Physical properties include density, color, odor,
hardness, melting/ freezing/ boiling points.

7
• Physical properties can be described as extensive
or intensive.
• Extensive properties depend on the amount of the
substance present. Length, for example is an
observable, extensive physical property.
• Intensive properties do not depend on the amount
of substance. Density, for example is an
intensive physical property, because the density
of a substance does not change, no matter how
much of the substance is present.

8
• Chemical properties of matter allow a substance
to change composition as a result of contact with
another substance or because of the application
of thermal or electrical energy. If a substance
is not reactive with another substance, HCl and
Copper, that is a chemical property, also.
• Examples of chemical properties include the
ability to rust, burn, release gas, absorb or
give off energy.

9
• All matter exists as either a solid, liquid, or a
gas. Plasma is also a form of matter, but is
only present on earth in lightning bolts. These
are called STATES OF MATTER. States of matter
are physical properties.
• Vapor is NOT the same as a gas!! A vapor is a
word used to describe when a substance that is a
solid or liquid at room temperature is heated
enough to take a gaseous form.

10
Solid Liquid Gas
Definite shape Definite volume Particles held tightly together Particles expand when heated Takes shape of container, but does not have to fill it Definite volume Particles held close, but not tight Particles expand when heated Takes shape of containers and fills it completely No definite volume Particles are far apart, so it can be compressed
11
Section 3.2
• Physical changes are changes which alter a
substance without changing its composition.
• Examples are breaking glass, tearing paper,
melting ice.
• Changes of state are physical changes. When
energy is added to solid water, it changes to
liquid water, when more energy is added, it is
changed to gaseous water. All the time it is
still water. Only a physical change has taken
place.

12
• Melting and boiling points are intensive physical
properties. They do not change when the amount
of substance changes. These intensive physical
properties can be used to identify unknown
substances.

13
• Chemical change is defined as one or more
substances combining to become one or more new
substances. AKA chemical reaction
• Examples of common chemical reactions include
burning wood, rusting iron, fermenting of barley
and hops to make beer, and explosions.

14
• Signs that a chemical reaction have taken place
include
• Thermal energy is given off or absorbed
• Light is produced
• Precipitate is formed
• Color has changed permanently
• Gas is formed

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16
• The Law of Conservation of Mass states that mass
is neither created nor destroyed in any process,
it is conserved.
• Mass of reactants Mass of products
• 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? How many
grams of sodium reacted?

17
• 24.1 g of chlorine gas is used in the reaction.
Because the sodium reacts with excess chlorine,
all of the sodium (15.6 g) is used in the
reaction.

18
Law of Conservation of Energy
• In any chemical reaction or physical process,
energy can be converted from one form to another,
but it is neither created nor destroyed.

19
Classify each of the following as examples of
physical or chemical changes
1. Crushing an aluminum can
2. Recycling used aluminum cans to make new cans
3. Aluminum combining with oxygen to form aluminum
oxide

20
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21
Section 3.3
• A mixture is a combination of two or more pure
substances in which each pure substance retains
its individual chemical properties. The
composition of a mixture is variable. Mixtures
can be heterogeneous or homogeneous.

22
• A heterogeneous mixture is one in which the
substances still remain distinct.
• Examples include sand/ water, Skittles, fruit
• The existence of two or more distinct areas
indicate a heterogeneous mixture.

23
• A homogeneous mixture has a consistent
composition throughout. It exists in one phase.
• Examples include salt and water, Kool-Aid, gold
jewelry.
• Homogeneous mixtures are often referred to as
solutions.

24
System Example
Gas-gas Air is primarily a mixture of nitrogen, oxygen, and argon gasses
Gas-liquid Carbonated beverages contain carbon dioxide gas in solution
Liquid-gas Moist air contains water droplets in air
Liquid-liquid Vinegar contains acetic acid in water
Solid-liquid Sweetened powder drink contains sugar and other solid ingredients in water
Solid-solid Steel is an allow of iron containing carbon
25
• A mixture is a combination of substances
physically combined. Physical separation methods
take advantage of known physical properties of
individual components of a mixture.
• Filtration uses a solid barrier to separate
heterogeneous mixtures of a a solid and a liquid
(sand water).
• Distillation uses differences in boiling points
to separate a homogeneous mixture.

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27
• Crystallization separates a mixture and forms a
solid that is pure. Like making rock candy.
• Chromatography separates components of a mixture
on the basis of the tendency of each to travel or
be drawn across the surface of another material.

28
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29
• http//streaming.discoveryeducation.com/search/ass
etDetail.cfm?guidAssetIDEAB00DCD-E1CF-469C-99E7-A
0AC8699954A

30
Section 3.4
• Elements are substances that cannot be broken
down any further by either chemical or physical
methods. Elements are pure substances.
• Elements have a unique name and chemical symbol.
The symbol consists of one, two or three
letters. The first letter is always capitalized
and any following letters are lowercase.

31
• The elements are grouped by patterns in their
physical and chemical properties.
• In 1869, Dmitri Mendeleev organized the elements
in rows and columns based on their masses. That
was the first version of the periodic table. One
of the greatest aspects of Mendeleevs table was
that it left spaces for elements not yet
discovered.

32
• The horizontal rows in the periodic table are
called periods and the vertical columns are
called groups or families. The table is called a
periodic table, because the elements have
patterns of similar properties as you move from
period to period.

33
• Compounds are two or more elements chemically
combined. The names of compounds are written by
using the elements symbols. Salt is written
NaCl, water is written H2O, hydrochloric acid is
written HCl.
• Compounds can be broken down into simpler
substances, unlike elements. In order to do
that, electrical or heat energy must be added.

34
• Compounds do not resemble the elements from which
from sodium (a silvery metal that burns when
exposed to water), and chlorine (a greenish,
poisonous gas). However, when these two combine,
they form simple table salt that flavors food.
• http//streaming.discoveryeducation.com/search/ass
etDetail.cfm?guidAssetIDE22926C5-4A5C-4797-834A-0
3E240843BD4

35
Law of Definite Proportions
• Regardless of the amount, a compound is always
composed of the same elements in the same
proportions by mass.
• The ratio of the mass of each element to the
total mass of the compound as a percentage is
called the percent by mass.
• Percent by mass
• mass mass of element x 100 mass
of compound