Physical and Chemical Changes Spring 2009. Kinetic Theory of Matter THEORY OF KINETIC ENERGY A....
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Transcript of Physical and Chemical Changes Spring 2009. Kinetic Theory of Matter THEORY OF KINETIC ENERGY A....
Physical and Physical and Chemical Chemical ChangesChanges
Spring 2009Spring 2009
Kinetic Theory of Matter Kinetic Theory of Matter
THEORY OF KINETIC ENERGY
A. ATOMS ARE ALWAYS MOVING
B. THE MORE ENERGY ADDED TO THE ATOMS, THE FASTER & FARTHER APART THEY MOVE
Physical ChangesPhysical ChangesMatter is always changing form, size, shape,
color, etc. There are 2 types of changes that matter undergoes.
PHYSICAL OR CHEMICAL CHANGEI. Physical Changes: a change of matter
without changing the identity of the matter. IN OTHER WORDS– A CHANGE IN STATE– A CHANGE IN SIZE, SHAPE, MASS– DOES NOT CHANGE THE CHEMICAL
MAKE UP OF THE MATTER– YOU HAVE WHAT YOU STARTED
WITH JUST IN A DIFFERENT FORM
Examples of Physical Examples of Physical ChangesChanges
- Verbs used to describe physical changes – grind, dissolve, erode, rip, tear, break, phase change (melt, freeze, condense, etc)
Other Physical Change Other Physical Change ExamplesExamples
• PAPER TORN INTO PIECES– SUGAR DISSOLVED INTO TEA– SALT DISSOLVED INTO WATER– NAILS OR HAIR CUT
Phase Changes are PHYSICAL Phase Changes are PHYSICAL PHYSICAL!!!!!PHYSICAL!!!!!
• Types of Phase Changes:• 1. Melting• 2. Freezing• 3. Vaporization• 4. Condensation• 5. Sublimation• 6. Deposition• ALL phase changes are caused by
ADDING or TAKING away energy!!!
• MATTER CHANGES FROM ONE STATE OF MATTER TO ANOTHER – WHEN HEAT (ENERGY) IS
ADDED– WHEN HEAT (ENERGY IS TAKEN
AWAY
• CHANGING STATES DOES NOT CHANGE THE CHEMICAL MAKE UP OF THE MATTER
• YOU HAVE WHAT YOU STARTED WITH JUST IN A DIFFERENT FORM
• ICE WATER WATER VAPOR• H2O H2O H2O
• WHEN MOLECULES MOVE FASTER, THEY PRODUCE MORE FRICTION AND THEREFORE MORE HEAT. THEY SPREAD FARTHER APART & EXPAND
• WHEN MOLECULES MOVE SLOWER, THEY CAUSE LESS FRICTION AND THEREFORE LESS HEAT & CLOSER TOGETHER & CONTRACT
MeltingMelting1. MELTING – GOING FROM A SOLID TO
A LIQUID– Energy is added– When more heat (energy) is added
to matter the particles move faster till the bonds break.
– Decrease density except ice to water.
Evaporation/VaporizationEvaporation/Vaporization2. EVAPORATION
– GOING FROM A LIQUID TO A GAS AT THE SURFACE
– ENERGY IS ADDED TO SURFACE OF LIQUID
– THE PARTICLES AT THE SURFACE MOVE FASTER breaking bonds.
– Decreases density.
BoilingBoiling3. BOILING
– GOING FROM A LIQUID TO A GAS ALL THROUGHOUT THE LIQUID
– ENERGY IS ADDED TO ALL OF LIQUID– PARTICLES MOVE FASTER ALL THROUGH
THE LIQUID– SOME PARTICLES MOVE FAST ENOUGH TO
CHANGE TO GAS WHILE THEY ARE IN THE MIDDLE OF THE LIQUID
– DENSITY DESCREASES– Water boils at 212 F, 100C.
• EX: pan of liquid on the stove
CondensationCondensation4. CONDENSATION
– CHANGING FROM A GAS TO A LIQUID– ENERGY IS REMOVED
•THE PARTICLES MOVE SLOWER•THE ATTRACTION BETWEEN THE
PARTICLES BEGAN TO PULL THE PARTICLES CLOSER TOGETHER & THE MATTER TURNS INTO A LIQUID
•DENSTITY INCREASES• Ex: dew in the lawn, water running down
mirror, ring on table under glass
FreezingFreezing• FREEZINGFREEZING
– CHANGING FROM A LIQUID TO A SOLIDCHANGING FROM A LIQUID TO A SOLID– ENERGY IS REMOVEDENERGY IS REMOVED
• THE PARTICLES MOVE EVEN SLOWERTHE PARTICLES MOVE EVEN SLOWER• THE ATTRACTION BETWEEN THE THE ATTRACTION BETWEEN THE
PARTICLES BEGAN TO PULL THE PARTICLES BEGAN TO PULL THE PARTICLES CLOSER TOGETHER & THE PARTICLES CLOSER TOGETHER & THE MATTER TURNS INTO A SOLIDMATTER TURNS INTO A SOLID
• Increase density.Increase density.• Water freezes at 32 F, 0 C• EX: water to ice, wax or chocolate
hardening
SublimationSublimation• 5. Sublimation: Substance goes straight• from a solid to a gas DRY ICE!!!!• Heat added rapidly• Molecules speed up and spread out• decrease density• Examples of Sublimation: dry ice, shrinking ice in a freezer
DepositionDeposition-Deposition is when a substance
changes from gas to solid.-Heat is taken away rapidly-Density increases-Molecules slow down and get closer
together.Examples:Snowflakes, frost on a wind shield
• WHAT HAS TO HAPPEN FOR THESE CHANGES OF STATES TO HAPPEN?
Chemical PropertiesChemical PropertiesII. Chemical Properties: properties
describes the ability of an object to change into a new substance. (flammability, reactivity)
Chemical Change verbs: rusting, rotting, curdling, burning, cooking, light sensitivity, digesting, tarnishing.
Chemical ChangesChemical ChangesThe other way that matter can be
changed is call a CHEMICAL CHANGE.
II. CHEMICAL CHANGE – occurs when 2 or more substances are combined into entirely new substance with all new properties. CANNOT CHANGE IT BACK!!!!!
Chemical ChangesChemical Changes• CHEMICAL CHANGE
– OR BROKEN DOWN INTO A DIFFERENT SUBSTANCE– SOME SIGNS OF A CHEMICAL CHANGE
• FIZZES OR BUBBLES• COLOR CHANGE• HEAT GIVEN OFF• LIGHT GIVEN OFF• ODOR• HEAT REQUIRED FOR REACTION• NEW SUBSTANCE FORMED
– Precipitate (solid)– Gas (bubbles)
• CHEMICAL CHANGE EXAMPLES– BAKING BREAD – NO LONGER
HAVE FLOUR, EGGS, MILK, YEAST
– ALKASELTER– BAKING SODA & VINEGAR– RUST– TARNISH