changing matter 2-3. objectives > explain physical change, and give examples of physical changes....
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Changing Matter 2-3
Objectives
• > Explain physical change, and give examples of physical changes.
• > Explain chemical change, and give examples of chemical changes.
• > Compare and contrast physical and chemical changes.
• > Describe how to detect whether a chemical change has occurred.
Phases of Matter• There are 4 phases of
Matter–Solid, Liquid, Gas, Plasma
–Molecules are always moving. They can vibrate and they can expand.
Molecular movement
• Solids – molecules constantly vibrating
• Liquids- molecules are spreading
• Gases – Molecules are expanding
Phases of MatterMatter can change from form to
form depending on the amount of energy (heat) is available.
Solid to liquid to gas.
Ice in a pan melts then begins to boil and turn to steam.
Phase changes & Temperature
___________ /
/
/
/
/
_________________
Phase changes occur at 1 temperature.
Physical Changes• Physical changes occur
without creating something new. They effect the physical properties of a substance. Such as melting, mixing, or dissolving. If you can change it back it is a physical change.
Chemical changes
• Chemical changes occur when the composition is changed and something different is created.
• You can tell because of odor, bubbles, color changes, sound, heat or light.
• Chemical Change Clip
Chemical changes• Chemical changes can not be
reversed to go back to original state.
• Chemical changes can break down compound such as water to create hydrogen and oxygen.
Phases of matter• Solids- definite shape and volume –Crystalline- orderly arrangement of atoms- diamond
–Amorphous-opposite- gum
Phases Cont’d• Liquid- definite volume no definite shape.–Surface tension-force acting on particles at the surface causing droplets to form.
Phases Cont’dPhases Cont’d
Gas- no definite shape Gas- no definite shape and no definite volume.and no definite volume.
Particles expand and Particles expand and spread out.spread out.
Change in phase/state• Condensation- energy
released when gas changes to a liquid
• Temperature and state do not change together
Energy must be added to separate the particles as ice melts; the same amount of energy is released when water freezes.
Energy is absorbed when water vaporizes; the same amount of energy is released when the water vapor condenses.
EnergyReleased to condense
EnergyabsorbedTo vaporize
–20 0 20 40 60 80 100 120 Relative energy Temperature (˚C)
100
90
80
70
60
50
40
30
20
10
0
Energy Released to Solidify Energy absorbed
to melt
Change in phase/state• Evaporization- energy
required to change liquid to gas
• Sublimation- energy required to change solid to a gas
• States of Matter Clip
Kinetic Theory
• All matter is made of atoms that act like particles
• Particles are always in motion, hotter= faster
Kinetic Theory Cont’d
• At same temperature heavier particles move slower than lighter particles.
Energy
• The ability to change matter and the capacity to do work–Kinetic energy – energy of motion
–Potential energy- energy of position
Energy Cont’d• Temperature- Average kinetic energy.
• Amount of particles do not matter
• High temperature means high kinetic energy
Energy Cont’d
–Thermal energy is the total kinetic energy of particles that make up the object.
–The bigger the object more T.E.
• Conservation of mass and energy– we cannot create or destroy either
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