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Matter

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Title: Matter


1
Matter
  • Honors Chemistry
  • Mrs. Partridge

2
Chemistry
  • The study of the properties and the changes that
    materials undergo.

3
Matter
  • Chemistry is the study of the composition of
    matter and changes in matter
  • Matter is anything that has mass and occupies
    space.
  • Mass is the measure of the amount of material in
    an object
  • The space that an object takes up is known as its
    volume

4
Matter
  • A quality that can be useful in identifying
    something is known as a property.
  • Classification of matter is the grouping of
    materials according to their properties

5
Physical Properties
  • Physical properties are those that can be
    observed and measured without changing the
    composition of the substance being observed
  • Examples
  • Boiling point
  • Melting point
  • Color
  • Physical state
  • Odor
  • Electrical conductivity
  • Solubility
  • Density
  • Taste
  • Hardness

6
Physical States of Matter (properties)
  • A. solid definite shape and volume each
    particle has a fixed position in relation to
    surrounding particles
  • B. liquid definite volume, indefinite shape
    each particle is free to move, but stays close to
    surrounding particles
  • C. gas indefinite shape and volume particles
    move freely and independently
  • As a standard of comparison, refer to the
    physical state of matter at ROOM TEMPERATURE
    because it may change states as the temperature
    changes.

7
Physical Properties
  • Intensive properties do NOT depend on the amount
    of matter present
  • Example density
  • Extensive properties depend on the amount of
    matter present
  • Example mass, volume

8
Chemical Properties
  • Chemical properties are those that are observed
    when a substance undergoes a chemical reaction
  • A new product must appear.
  • Flammability (the ability to react rapidly with
    oxygen)
  • Rusting
  • Reactivity

9
Physical Changes
  • Physical changes cause NO change in the basic
    nature or composition of matter
  • Mixing together or separation two or more pure
    substances is a physical change
  • Change in size, shape or color are physical
    changes

10
Physical Changes
  • All changes of state are considered physical
    changes
  • Changes of STATE depend on the direction of heat
    flow
  • Changes are reversible
  • Melting solid turns to liquid
  • Freezing liquid turns to solid
  • Melting and freezing occur at the same
    temperature melting point or freezing point.
    Also can be called temperature of fusion
  • Measured when both solid and liquid states are
    present

11
Physical Changes
  • Vaporization Liquid turns to a Gas
  • Evaporation is vaporization at the surface of a
    liquid

12
Physical Changes
  • Condensation Gas turns to a liquid
  • Boiling point is the temperature at which bubbles
    form throughout a liquid and the liquid becomes a
    gas. Vaporization occurs throughout the liquid
  • Measured when both liquid and gas states are
    present

13
Physical Changes
  • Sublimation solid turns directly into a gas
  • Deposition gas turns directly into a solid

14
Chemical Changes
  • Chemical changes are changes in matter in which
    NEW substances (products) with different
    properties are formed
  • Evidence of change may be gas formation and
    precipitation (solid formation)
  • Examples rusting iron, burning paper

15
Types of Matter
16
Pure Substances
  • Have a constant composition, a distinct set of
    properties that can be used to identify it, and
    can be a solid, liquid, or gas

17
Elements
  • Pure substances that can not be broken down!
  • Everything in the world is made up from only 112
    different elements
  • 90 of the human body is composed of only three
    elements Oxygen, Carbon Hydrogen

18
Compounds
  • Pure substances that CAN be broken down into
    simpler substances only by CHEMICAL means
  • Two or more elements chemically combined
  • Compounds are substances of 2 or more elements
    united chemically in definite proportions by mass

19
Compounds
  • The properties of a compound are different from
    the properties of the elements that make it up

20
Mixtures
  • Mixtures are two or more pure substances
    physically combined
  • Mixtures can be separated into the substances of
    which they are made by physical means (examples
    filtration, magnet, evaporation)

21
Mixtures
  • Mixtures have varying proportions of components.
  • Mixtures display changing properties as the
    properties of the components of the mixture change

22
Heterogeneous Mixtures
  • Heterogeneous mixtures dont have the same
    properties throughout. They consist of two or
    more substances that are mixed but NOT chemically
    joined

23
Suspension
  • A heterogeneous mixture that contains particles
    large enough to be separated by using a filter

24
Colloid
  • A mixture containing solid particles that are
    small enough to remain suspended
  • Examples clay, latex, shaving cream

25
Homogeneous Mixtures
  • Homogeneous mixtures have the same properties
    throughout the substances are evenly
    distributed 1 phase
  • Also called a solution

26
Alloy
  • Solid Solutions

Bronze
Steel
27
Solvent
  • The substance in which another substance dissolves

28
Solute
  • The substance that dissolves in a solvent

29
Saturated Solution
  • A solution that contains the maximum amount of a
    substance that will dissolve at a given
    temperature
  • When cooled, the excess solute will generally
    precipitate
  • If cooled carefully, the excess solute will
    remain dissolved making a super saturated
    solution one that holds more solute than can
    normally be dissolved at that temperature

30
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31
Solubility
  • Solubility is the maximum amount of substance
    that will dissolve in a given amount of solvent
    at a given temperature
  • Can be used to identify a substance
  • Hot water dissolves more SOLID
  • Cold water holds more GAS

32
Solubility Graph
33
Distillation
  • Purification process in which a liquid is
    evaporated and then condensed again to a liquid
  • Used to separate dissolved solids from liquids or
    liquids from liquids according to boiling point

34
Law of Conservation of Mass
  • In any physical change or chemical reaction, mass
    is neither created nor destroyed it is conserved

35
Energy
  • Physical and chemical changes always involve
    energy transfer, either in the form of work or
    heat, between a system and its surroundings.
  • When we focus on a study of energy changes we
    look at a small, well defined and isolated part
    of the universe the flask or container the
    reactants are in. This is called the system.

36
Energy
  • Everything else is called the surroundings.
  • Usually the system is isolated from its
    surroundings such that there will be an exchange
    of energy between system and surroundings, but
    NOT matter!
  • So. . . the system will contain the same mass
    after an experiment, but the system can lose or
    gain energy (in the form of heat, work, or both).

37
Energy
  • Systems tend to attain as low an energy as
    possible!

38
Energy
  • Systems with a high potential energy are less
    stable and more likely to undergo change than
    systems with a low potential energy.
  • Like a shopping cart at the top of a hill,
    chemical reactants move spontaneously toward a
    lower potential energy when possible.

39
Energy
  • Energy transferred as as result of a temperature
    difference is called heat.
  • When a chemical reaction occurs in an open
    container most of the energy gained or lost is in
    the form of heat.
  • Heat flows between the system and surroundings
    until the two are at the same temperature
    equilibrium.

40
Energy
  • When a chemical reaction occurs in which the
    system absorbs heat, the process is endothermic
    (it feels cold).
  • When a chemical reaction occurs in which the
    system produces heat, it is exothermic (it feels
    hot).

41
Energy
  • Both endo and exothermic reactions require some
    minimum amount of energy to get started. This is
    known as the activation energy.

42
Energy Units
  • The SI for energy is the joule (J).
  • However, energy changes accompanying chemical
    reactions are expressed typically expressed in
    calories.
  • 1 calorie 4.184 J
  • A dietary Calorie is 1000 times larger as a
    calorie a kilocalorie.

43
Calorimetry
  • We can determine the heat flow (?Hrxn) associated
    with a chemical reaction by measuring the
    temperature change it produces.
  • Calorimetry is the measurement of heat flow.

44
Calorimetry
  • A calorimeter is an apparatus that measures heat
    flow.

45
Heat Capacity
  • The heat capacity of an object is the amount of
    heat energy required to raise its temperature by
    1 K or 1C.
  • The greater the heat capacity of an object, the
    more heat energy is required to raise the
    temperature of the object.

46
Specific Heat
  • For pure substances the heat capacity is usually
    given for a specific AMOUNT of the substance.
  • The heat capacity of 1 gram of a substance is
    called its specific heat.

47
Specific Heat
  • The specific heat (Cp) of a substance can be
    determined experimentally by measuring the
    temperature change (?T) that a known mass (m) of
    the substance undergoes when it gains or loses a
    specific quantity of heat (q).
  • Cp q/(m) (?T) or q (m) (?T) (Cp)
  • Unit for specific heat is usually J/gC

48
The end!
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