Download Unit 1 Energy Part (b) - Chemistry Digital Learning

10/5/2016
What is energy?
Energy is the ability of a system to
do work or supply heat.
Forms of energy
Light
Energy is NOT matter because it does
not take up space nor does it
have mass
Heat
Sound
https://vimeo.com/123271598
Electricity
Energy Types
1. Potential: energy due to
its distance from other
objects (stored energy)
Types of KE
Motion
Thermal Energy
Sound Energy
Electromagnetic Radiation
Electric Energy
2.Kinetic: energy of
motion
Kinetic Energy as Motion
Kinetic Energy as Thermal Energy
Airplane flying or meteor plummeting
Thermal energy is directly related to TEMPERATURE.
Related to the mass of the object and its velocity.
We can’t see individual atoms vibrating, but we can feel their kinetic
energies as temperature.
1
10/5/2016
TEMPERATURE- is a measure of the
average KE of the particles.
A MEASURE OF THE AVERAGE KE OF THE PARTICLES!
Kinetic Energy as Sound Energy
Sound waves are made when stuff vibrates– like strings on an instrument
or gas molecules in the air.
Sound waves travel when the vibrating stuff causes stuff surrounding it to
also vibrate.
Sound doesn’t travel in a vacuum, because a vacuum has no atoms to
transmit the vibration.
Electromagnetic Radiation- KE
Electric Energy
Electromagnetic Energy is the same as radiation or light. This type of
energy can take the form of visible light, UV radiation, radio waves, or Xrays.
Electric energy is the kinetic energy of moving electrons, the negativelycharged particles in atoms.
Physicists describe electromagnetic radiation as being composed of
PHOTON (tiny packets of energy).
Each photon has a particular amount of energy.
Types of PE
Chemical Potential Energy
Electricity is the KE of flowing electrons between atoms.
Chemical Potential Energy
Chemical energy is stored in the bonds
between atoms in compounds. This stored energy is
transformed when bonds are broken or formed through
chemical reactions.
Nuclear Potential Energy
Gravitational Potential Energy
Mechanical (Elastic) Potential Energy
2
10/5/2016
Nuclear Potential
energy
Gravitational Potential Energy
Systems can increase gravitational energy as a mass moves away from the
center of the Earth or other objects that are large enough to generate
significant gravity (our sun, the planets and stars)
Today’s nuclear power plants are
fueled by fission. Uranium or
plutonium atoms are broken
apart, freeing lots of energy.
Hydrogen atoms in the sun
experience nuclear fusion,
combining to form helium and
subsequently releasing large
amounts of energy in the form of
electromagnetic radiation and
thermal energy.
Most atoms are stable on
Earth; they keep their
identifies as particular
elements. Nuclear
reactions change the
fundamental identify of
elements by changing the
nuclei of the atoms.
Mechanical (Elastic)
Potential Energy
Elastic energy can be stored mechanically in a compressed
gas or liquid, a coiled spring, or a stretched elastic band.
On an atomic scale, the stored energy is a temporary strain
placed on the bonds between atoms, meaning there’s no
permanent change to the material. These bonds absorb
energy as they are stressed,
and release the energy as they relax.
Power plants transform
chemical potential energy in
fossil fuels to electricity.
Energy can shift forms, but is
never created or destroyed!
A car transforms the PE
trapped in gasoline into
various types of energy that
move the car. Most is
converted to thermal
energy (heat).
Nuclear Power plants
change the nuclear
potential energy of
uranium or plutonium into
electricity too.
An efficient fossil fuel plant
loses more than half of the
energy it creates to forms other
than electricity, such as heat,
light, or sound
3
10/5/2016
Wind turbines change the KE
of air molecules in wind into
electricity.
Hydroelectric power plants take
advantage of gravitational
potential energy of water as it falls
from the top of a dam to the
bottom.
On the Arizona-Nevada border to
tame the Colorado River and
provide water and hydroelectric
power for the developing
Southwest.
http://www.history.com/topics/
hoover-dam (5 mins)
Laws of Conservation
Example:
Chemical energy transferred into
and = light energy
Energy:
• Energy is neither created nor destroyed
• The amount is TRANSFERRED!!
Example:
Heat absorbed by cold pack = Heat
lost by surroundings
Hungary Dragon Demo
Energy in Reactions
Exothermic: gives off energy (heat, light)
+
Signs of a change from chemical potential energy to other
forms of energy.
=
(The surroundings feel HOT)
https://youtu.be/18sifodnVDo
Endothermic: absorb energy (cold)
(The surroundings feel COLD)
4
10/5/2016
Temperature vs. Heat (MOTION)
Temperature: measures average kinetic energy
of particles
Cup of water and a bathtub of water
are both at 30° C.
WHICH HAS MORE HEAT ENERGY?
Heat: sum total of kinetic energy of the
particles (ENERGY!!)
The
bathtub
because it
has more
mass!!!
Temperature Scales
°C = K – 273
Absolute Zero = 0 K = - 273 °C
1) °C = ?, K = 300
Kelvin (K)
Water freezes at 273 K
Water boils at 373 K
2) °C = ?, K = 401
Celsius (°C)
Water freezes at
0 °C
Water boils at 100 °C
3) K = ?, °C = -26
°C = 27
°C = 128
K = 247
°C = K – 273
Laws of Conservation
Mass:
• mass is neither created nor destroyed in
chemical reaction. (THE ATOMS ARE MERELY
REARRANGED>)
• Start with 50.0 grams, End with same!
+
25.0 g +
=
25.0 g
=
50.0 g
5