Transcript Chemistry - Lyons USD 405

Chemistry
Icy Hot Lab
Safety
Wear your safety goggles at all times!
 Keep loose clothing and hair back and
away from the Bunsen burner flame.
 The beakers will get hot! Use the beaker
tongs to remove the beaker and dispose of
boiling water in the sink.

While you wait
Sketch a diagram illustrating the particles
of solid water (ice), liquid water, and water
vapor (gas).
 Describe the shape, volume, and mass of
water as it changes from one phase (state)
to the next. For example: Solid water has
a constant shape – meaning the cubes of
ice hold their shape when dumped onto
the table.

While you wait
Pick up a copy of the Energy and Kinetic
Theory of Matter Reading.
 Read page 1. In your chemistry journal,
list the three guiding principles used to
understand energy.
 Read page 2. Use a graphic organizer to
compare / contrast money and energy.

Energy Reading page 2
What are the three energy “accounts”
used to explain changes in substances or
their arrangements in chemistry.
 What are the three ways to transfer energy
into or out of a substance?

Law of Conservation of Energy
Energy can be transferred from one
“account” to another during chemical or
physical processes.
 Total energy (like mass) before the change
equals the total energy (mass) after the
change as long as no energy (mass)
enters or leaves the system.

1st Law of Thermodynamics

If energy is transferred into or out of the
system, the change in energy equals the
energy transferred by heating, working, or
radiating.
ΔE = Q + W + R
Kinetic Theory of Matter

Matter is made up of tiny particles that are
in constant motion.

Kinetic Theory of Matter Simulation
Kinetic Theory of Matter
These particles exert long range
attractions and short range repulsions on
each other. Attractions reduce the
interaction energy (Ei) while repulsions
increase interaction energy.
 Phase Change Simulation

Kinetic Theory of Matter

A warmer sample has (on average) faster
moving particles than a cooler sample.
Icy Hot Lab Results
Kinetic Energy
Energy Transferred (Heat)
Discussion Questions: Chemical or
Physical Change?

Was the observed phase changes a
chemical change of a physical change?
How do you know?
Discussion Questions: Endothermic
or Exothermic Change?
Endothermic change – Change caused by
the transfer of energy (heat) into a
substance.
 Exothermic change – Change caused by
the transfer of energy (heat) out of a
substance.
 Where the phase changes you observed
in the lab exothermic or endothermic?

Discussion Questions: Kinetic
Energy or Interaction Energy?
Was the energy transferred to the
substance stored as kinetic energy? How
can you tell from the Temperature vs. Time
graph?
 Was the energy transferred to the
substance stored as interaction energy?
How can you tell from the Temperature vs.
Time graph?

Discussion Questions: Heating
Slowly or quickly?

How would the Temperature vs. Time
graph change if we used two bunsen
burners instead of one?