Matter and Energy

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Matter and Energy
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What is the relationship between matter, mass,
and weight?

• Matter anything that has mass and volume (takes
  up space)
• Mass the amount of matter in an object
• Weight the amount of matter in an object
  including the effect of gravity on the matter
• Measured in grams or kilograms
• Weight is measured with a scale
• Mass is measured with a balance
• Mass and weight are not the same

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Vocabulary

• Volume the amount of space an object takes up
• Atoms the basic building block of matter the
  smallest particle of an element that has the same
  properties as that element
• Molecules a neutral group of atoms held
  together by chemical bonds

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Matter can be described by its chemical and
physical properties

• Physical Properties - Characteristics that can be
  observed or measured without changing the
  composition of matter
• Color, mass, volume, texture, state, anything
  that can be measured with an instrument
• Chemical Properties - Characteristics that can be
  observed only when substances interact with one
  another
• Flammability, reactivity with acid

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Matter changes through physical and chemical
changes

• Physical Changes - Any change in matter that does
  not change its identity
• Change in size, changes in state
• Chemical Changes - Any change in matter in which
  its identity is changed
• Burning, tarnishing, evolution of heat or gas

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What is energy?

• The ability to do work
• Is measured in joules (J)
• Two types of energy (on the atomic level)
• Potential
• Kinetic
• Energy cannot be transformed from one type to
  another without any loss

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What is potential energy?

• Stored energy

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What is kinetic energy?

• Energy of motion

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What is the Law of Conservation of Energy?

• Energy in any closed system is neither created
  nor destroyed
• Mass can be described in terms of energy by using
  Einsteins equation, E mc2
• E energy, m mass, c velocity of light (3.0
  x 108 m/s)

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What are endothermic and exothermic?

• Exothermic energy is released into the
  surroundings, and the object feels warm (giving
  off heat)
• Endothermic energy is absorbed from the
  surroundings, and the object feels cool
  (absorbing heat)

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What is the difference between a mixture and a
pure substance?

• Pure substance matter composed of only one kind
  of atom or molecule (element or compound)
• Mixture a physical combination of two or more
  pure substances

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What is the difference between elements and
compounds?

• Element the simplest pure substance formed of
  a single kind of atom
• There are 117 known elements Allotropes
  different molecular forms of an element in the
  same physical state
• Examples graphite, diamond and bucky balls

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Elements
Sulfur
Copper
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Allotropes of carbon
Other elements that have allotropes include
phosphorus (white, red and black), sulfur
(plastic, molecular, rhombic and monoclinic), and
oxygen (ozone, tetraoxygen)
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What are compounds?

• Pure substances composed of two or more different
  elements joined together chemically
• Possess different physical and chemical
  properties from the parent elements
• Examples salt from Na and Cl water from H2 and
  O2
• Have a definite composition by mass of their
  combining elements

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Compounds
Sugar made of hydrogen, oxygen and carbon
Water made of hydrogen and oxygen
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What are the two different categories of mixtures?

• Homogeneous a mixture containing substances
  that are uniformly distributed (same throughout)
• Milk, tea, sodas, gold and silver jewelry,
  whipped cream, Kool-Aid, etc.
• Heterogeneous a mixture containing substances
  that are not uniformly distributed (not same
  throughout)
• Cereal, hamburgers, concrete, pepper, etc.

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Sand
Muddy Water
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How can mixtures be separated?

• Six different methods
• Filtration separating using a filter
• Evaporation extra moisture is evaporated from
  the mixture
• Centrifuge spinning a mixture centrifugal
  force pushes dense matter outward
• Decant pouring off liquids and leaving solid
  behind
• Distillation separation using different boiling
  points
• Chromatography separation using a stationary
  and a mobile phase

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What is density?

• Mass per unit volume. Physical property that
  describes how much stuff can be put into a
  space.
• Example feathers are not dense, but lead is
  very dense
• Formula mass/volume
• Density Mass
• Volume (mL or cm3)

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How are density problems solved?

• The volume of a sample of water is measured to be
  10.5 ml, and its mass is measured to be 9.98 g.
  What is its density?

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How are density problems solved?

• A substance has a density of 2.70 g/cm3. If a
  sample has a volume of 3.0 cm3, what will its
  mass be?

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How are density problems solved?

• A substance has a density of 3.251 g/cm3. What
  would be the volume of a 10.00 g sample of this
  substance?

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Law of Definite (Constant) Composition

• In a given compound, the relative numbers and
  kinds of atoms are constant
• Example Water is 11.2 hydrogen and 88.8
  oxygen (by mass, not volume) regardless of how
  much water you have.

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Law of Conservation of Mass

• The total mass of materials present after a
  chemical reaction is the same as the total mass
  before the reaction.
• For example, if 200 g of compound A react with 16
  g of compound B, the product, AB, will have a
  mass of
• 200 g 16 g 216 g.
• A B AB

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Law of Multiple Proportions

• If two elements, A and B, combine to form more
  than one compound, the masses of B that can
  combine with a given mass of A are in the ratio
  of small whole numbers.
• For example, H2O, 16.0 g of O react with 2.0 g of
  H. In H2O2, 32.0 g of O react with 2.0 g of H.
  The ratio of O in H2O2 to O in H2O is 32.0 g/
  16.0 g 2