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Batteries 3 Parts: Cathode (positive charge), anode (negative charge) and an electrolyte (substance with free ions (atoms with a net charge) Reactions occur at the anode which release electrons, they want to flow toward the cathode. But the electrolyte keeps the electrons from flowing to the cathode. If you create a closed circuit, and provide the electrons an alternate path to flow to the cathode, then they will follow that path. Now the chemical reactions at the anode change the anode and the electrolyte chemical composition, and eventually they can no longer occur. So the battery no longer produces electrons and current. When you recharge a battery ,you reverse the flow of electrons through the battery and reverse the the chemical process, restoring the battery to almost its original chemical state.
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Chemical Energy Energy that is released via chemical
reactions.
Often times release is through combustion such as energy generation
via coal Another example is a battery Batteries 3 Parts: Cathode
(positive charge), anode (negative charge) and an electrolyte
(substance with free ions (atoms with a net charge) Reactions occur
at the anode which release electrons, they want to flow toward the
cathode. But the electrolyte keeps the electrons from flowing to
the cathode. If you create a closed circuit, and provide the
electrons an alternate path to flow to the cathode, then they will
follow that path. Now the chemical reactions at the anode change
the anode and the electrolyte chemical composition, and eventually
they can no longer occur. So the battery no longer produces
electrons and current. When you recharge a battery ,you reverse the
flow of electrons through the batteryand reverse the the chemical
process, restoring the battery to almost its original chemical
state. Earliest batteries-Baghdad battery
Also called the Parthian Battery Artifacts discovered in 1936 near
Baghdad. Terracotta jar 5 inches tall, containing a copper rolled
up copper sheet housing a single iron rod. If it were filled with
an acidic liquid, it could produce a current Use as a battery is
uncertain, many different interpretations exist. Leyden Jars Device
that stores static electricity
Earliest form of what we now call a capacitor Glass jar with metal
foil coating the inner and outer surfaces. A rod is connected to
the inner foil and sticks out of the mouth of the jar. Need to be
initially charged Galvanic Cells First attempt to derive energy
from chemical reactions
Consists of two metals (often copper and zinc) in a solution of a
salt of the metal, connected by a salt bridge (really just a porous
plate) Also called voltaic cells or electrochemical cells Voltaic
pile First true electric battery
Alessandra Volta first showed that when copper and zinc discs are
separated by cardboard soaked in brine, they act as a galvanic
cell. He further showed that if you stack several pairs of these,
you get a current to flow. Inside a modern battery Leaky batteries
Alkaline batteries-popular form of battery for many devices Uses
potassium hydroxide, which is an alkaline as the electrolyte,
instead ofammonium chloride or zinc chloride. All three are acids
and can corrode the outer steel shell and leak. In addition, as a
battery is discharged, Hydrogen as is formed, which increases the
pressure inside the battery. This can rupture the seals on the ends
of the battery or the battery canister itself. They create a
crystalline structure on the outside of the battery. It can cause
oxidation on copper leads and damages circuits. A solution of water
and baking soda or vinegar can be used to attempt to clean corroded
contacts. Lithium ion batteries In these batteries, lithium ions
are extracted from the anode and inserted into the cathode to
create a current. The electrolyte is often a lithium salt in a
solution of ethylene carbonate Note: a lithium battery is a
different battery, it has a lithium anode-these have a longer
lifetime and can produce higher currents and voltages. Celsius
another scale using height of liquid in a tube
Heat Energy Temperature Scales: Fahrenheit based on the height of
liquid (often mercury or alcohol) in a glass tube. Celsius another
scale using height of liquid in a tube Kelvin-absolute scale True
measure of energy Energy associated with the random motions of the
molecules in a medium. Measured by temperature Fahrenheit
temperature scale
Freezing point of water set at 32 and boiling point set at 212, so
there is 180 degrees between them and each degree is 1/180 of the
difference between these two points. Celsius temperature
scale
Freezing point of water set at 0 and boiling point set at 100, so
there is 100 degrees between them and each degree is 1/100 of the
difference between these two points. Kelvin temperature scale
O K is absolute zero. All molecular motion stops. Interval set so
that 1 K = 1 C So to convert from C to K K=C+273 To convert from F
to K: K =(F - 32) * 5/ Energy and mass are equivalent C = 3 x 108
m/s.
Mass Energy E = mc2 Energy and mass are equivalent C = 3 x 108 m/s.
C is a big number and its squared! So even if m is small, E is big.
A small mass, converted to energy, gives a lot of energy!
Example