Download 3 CO 2(g)

Chemical and Physical Changes
Notes and Lab
Warm - Up
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What is matter?
How is a solid like a liquid?
What is the Law of Conservation
of Matter?
What are crystalline solids?
What causes matter to change
states?
Objective
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Today I will be able to:
◦ Differentiate between a chemical and physical
change
◦ Explore the properties of chemical and
physical changes by completing a lab.
Homework
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STEM Fair Experimental Design due
Monday
◦ First notebook check!!!!
Agenda
Warm – Up
 STEM fair concerns?
 Chemical and Physical Changes Notes
 Lab Safety
 Lab
 Exit Ticket – Chemical and Physical
Changes Practice
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Chemical and Physical Changes
Physical Properties
Description of a substance
undergoing a physical change
 Intensive Properties – do not depend
on the amount of matter present
(density, boiling point, freezing point,
color, odor)
 Extensive Properties – depend on the
amount of matter that is present
(mass, volume, pressure, length)
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Chemical Properties
 Enables
a substance to change into a
brand new substance, and they
describe how a substance reacts with
other substances
Changes in Matter
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Through experimentation and
natural occurrences, matter tends
to change in either of two ways
- Physical Changes
- Chemical Changes
Physical Changes
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Only physical properties change
The form of matter changes, but
the identity of the matter remains
the same
Examples: change in state (phase
change), breaking a pencil, tearing
paper
Physical Changes
 Phase
Change – physical process in
which one state of matter is
transformed into another
Physical Changes
Physical Changes
 During
a change of state, the
temperature remains constant, but
energy must be continually transferred
because the particles that make up the
sample have different quantities of
potential energy before and after the
change
Physical Changes
Physical Changes
Chemical Changes
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Properties of original substance
disappear as new substances with
different properties are formed
Change in chemical composition
Cannot return to original form
Can be detected through – energy
changes (temperature), change in color,
emission of gas, solid formed
Examples – wood burning, iron rusting,
sour milk
Examples – Chemical or Physical
Change?
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A match lights when struck
Wood is placed into a chipper
A lump of gold is pounded into a large,
thin sheet
Baking powder bubbles and gives off
CO2 when it is moistened
A pan of water boils on the stove
Hydrogen Sulfide gas causes silver to
tarnish
Reactions Involving Energy
 Most
chemical reactions, physical
changes of state, and dissolving
processes involve energy changes
 Energy can be released or absorbed
 Exothermic Reactions
 Endothermic Reactions
Reactions Involving Energy
 Exothermic
Reactions – reactions
that release energy into their
surroundings
- Results in a temperature increase
- Feels warm to the touch
 Example Reaction – Combustion of
Propane
- C3H8(g) + 5 O2(g)  3 CO2(g) + 4 H2O(g) + 2043
kJ
Reactions Involving Energy
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Endothermic Reactions - reactions
that absorb energy from their
surroundings
- Results in a temperature
decrease
- Feels cold to the touch
Example Reaction –
Photosynthesis
- Sunlight + 6 CO2(g) + H2O(l)  C6H12O6(aq) + 6
O2(g)
Lab Safety
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Closed toe shoes, goggles, aprons must be worn
to participate
Hair must be tied back
Review Bunsen burner safety
In step 3, DO NOT stare directly into the light
HCl, sodium chromate and barium nitrate are in a
low concentration, if you spill it just rinse it off of
your skin in a sink
Dispose of all chemicals in the waste container,
DO NOT pour directly down the sink
Exit Ticket
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Complete the worksheet stating if each
event is a chemical or physical change