Chapter 2 Notes

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Chapter 2 Notes

• Sept 2011

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Matter and Energy

• Kinetic Theory explains the difference between
  the states of matter
• Atoms and molecules are made of tiny particles
• Particles are always in motion
• Higher the temperature fast movement
• Lower the temperature slow movement
• At same temperature, massive particles move
  slower than less massive particles.

Having more mass
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States of Matter

• Solid
• Very close together
• Only vibrate back and forth.
• Definite shape and volume.

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• Liquids
• Free to move around
• Able to flow
• Take shape of container

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• Gases
• Particles far apart
• Constantly moving fast
• Free to move around
• Take shape of container

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• Plasma
• Most common state of matter in Universe
• Makes up starts
• Conducts electricity

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Thermal Energy

• KE of a substances atoms
• S Low KE
• L
• G
• P High KE

Energy in Motion
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Temperature

• Average amount of KE particles have

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Change of State

• Endothermic Requires Energy
• Adding energy
• IE ice melting, solid ? liquid
• Exothermic Gives off Energy
• Fire

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Exothermic
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Vocabulary

• Evaporation Liquid ? Gas
• IE Lake water evaporating into the atmosphere
  as water vapor
• Sublimation Solid ? Gas
• IE Dry Ice Solid CO2 ? CO2 Gas
• Condensation Gas ? Liquid
• Water Vapor condensing on Glass

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• Energys Role
• What happens to ice when you heat it up?
• What happens to a pot of water when you put it on
  the stove?
• In both of these examples energy is being added
  to matter in order to change its state.
• Melting is when energy is added to a substance in
  order to change it from a solid to liquid.
• Evaporation is when enough energy has been added
  to a substance to change it from a liquid to a
  gas.
• In some special occasions solids can turn
  directly into gases. This is called sublimation.
  

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• What happens on the outside of a glass of ice
  cold soda?
• Condensation is when energy leaves a gas and the
  gas changes back into a liquid.
• Changing the state of matter is like climbing a
  ladder.
• As you move up the ladder you gain energy and as
  you move back down you lose energy. At certain
  points as you gain enough energy you change from
  a solid to a liquid to a gas. As you go back down
  the ladder you change back from a gas to a liquid
  to a solid.
• Does your composition or mass ever change as you
  climb up or down the ladder?
• Ice, water, and steam all have the same chemical
  formula, H2O. The only difference is that each
  one has different amounts of energy.

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Heat Curves

• Start video at 902 for Graphs of Water and Iron

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• Law of conservation of Mass
• Mass cannot be created of destroyed.
• The total amount of matter stays the same before
  and after a change.

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Conservation of Mass Energy

• Mass and energy cannot be created or destroyed
• It can be Transferred!
• Energy During Chemical/Physical Chgs

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Properties of Matter (2.2)

• What eventually happens to a very old car when
  its left outside and not taken care of?
• Rust is a chemical property of the steel that the
  car is made from.

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• Describe the physical appearance of your teacher.
• Physical properties - are characteristics of a
  substance that can be observed or measured
  without changing the composition of the
  substance.
• Melting point is the temperature at which a solid
  becomes a liquid.
• Boiling point is the temperature at which a
  liquid becomes a gas.
• Density is the mass per unit volume.
• D M / V

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Chemical Properties

• Chemical property - Substances reacting to form
  new substances with different properties.
• Reactivity - Ability of a substance to combine
  chemically with other substances
• Flammability the ability of a substance to
  react in the presence of oxygen and burn

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Chemical and Physical Changes

• Chemical changes occur when a substance changes
  composition by forming one or more new
  substances.
• Original substance(s) no longer exists.
• Signs of Chemical Change
• color
• odor
• Give an example of a chemical change.

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Chemical and Physical Changes

• Physical Changes do not change in composition.
• Substance may look different
• Composition is the Same
• Give an example of a physical change.
• Dissolving
• Salt water tastes the same as table salt, because
  the composition of the salt does not change when
  dissolved.

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Density

• Dm/v units are grams/ml or grams/cm3
• What is the density of an object that has a mass
  of 1348g and a volume of 23ml
• A rock has a density of 2.6g/cm3. If it has a
  mass of 648 grams how much volume does it have?

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Density

• A piece of metal has a volume of 600 cm3, and a
  density of 0.15 g/mL. What is the mass of the
  piece?
• A brick is 4cm long, 6 cm wide, and 2 cm high,
  and a mass of 1.2 Kg. What is its density?

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Bell Work

• What is the volume of an object that has a
  density of 10.2 g/cm3 and a mass of 96.3 g?

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Density

• Why does Ice float on water?
• Bouyancy the force with which a more dense
  fluid pushes a less dense fluid upward
• How can a steel battleship float on water?

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Volume of Water Displaced Volume of Object
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Buoyant Force

• Upward force exerted on an object immersed in or
  floating on a fluid
• Explains Why Objects Float

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Archimedes Principle

• Buoyant force on an object in a fluid is an
  upward force equal to the weight of the volume of
  fluid that the object displaces.

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Fluid

• Nonsolid state of matter in which the atoms or
  molecules are free to move past each other
• IE Gas or Liquid
• All Fluids exert pressure
• Even in all Directions

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Pressure

• Amount of force exerted per unit area of a
  surface
• Fluids
• As depth increases, pressure increases
• SI unit for Pressure Pascal (Pa)

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Pascals Principle

• Fluids exert pressure equal in all directions
• p1 p2
• pressure1 pressure2

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Viscosity

• Resistance of a fluid to flow
• IE
• Honey is more VISCOUS than water

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Properties of GASES

• Fluid
• Compressible
• Very Low Density
• In Constant Motion
• Frequently Collide
• No Definite Shape/Vol.
• Mix with One and Other

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• Liquid particles are somewhere in between solids
  and gases. They move faster than solid particles
  and slower than gas particles.
• Liquids can be differentiated by the way in which
  they spread out. This physical property is
  called viscosity.
• Viscosity is the resistance of a fluid to flow.
• Gas particles are very spread out, so much so
  that they are able to take the shape of their
  container.
• Gases can exert pressure on the walls of the
  container it is in.
• Pressure is the force of the moving molecules on
  the surface of the container.
• What are two ways of increasing the pressure in a
  container?

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