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Cells and Batteries
Section 1.4
http://mustridenow.com/build-lightweight-lithium-battery/
Review-Section 1.3

What is more dangerous, current or
voltage? Why?
Both are dangerous.
 Current- When someone is shocked it’s
the amount of current that causes the
damage. Even small current can kill.
 High
voltage- Dangerous because it
drives current.
The Plan

Discuss types of cells, watch video clips
and an animation, look at batteries, and
brainstorm.

I can explain the difference between dry and
wet cells.

I can explain how a battery is made.
Electrochemical Cell

The energy source of a
pacemaker is usually an
electrochemical cell.

An electrochemical cell is a
package of chemicals designed
to produce small amounts of
electricity; produces electricity
from chemical reactions.
 Two main types
1. Dry cells
2. Wet cells
of cells:
Batteries
 Batteries
are two or more cells
connected together.
A
battery is essentially a can full of
chemicals that produces electrons.
Battery Terminals
Every battery has two terminals:

1) One terminal is marked (+) or positive.
2) Other terminal is marked (-) or negative.

In an AA, C, or D cell (normal flashlight
batteries), the ends of the battery are the
terminals.

In a large car battery, there are two heavy
lead posts that act as the terminals.
Dry Cells

Dry cells are the electricity-producing cells
that has its electrolyte in the form of a
paste, usually in a sealed case.

Called “dry” because the chemicals are in a
paste so they can be placed in any position
without leaks.
Devices that are
Powered by Dry Cells
Dry Cells

The type of cell we use every day. Dry
cells are commonly used in portable
devices (e.g., flashlights).
https://musicianstools.wordpress.com/2009/01/07/sta
y-gripped-to-your-music-with-the-ibikeconsole/
http://vlab.ethz.ch/flashlight/
How Do Dry Cells Work?
1.
2.
3.
4.
http://pixshark.com/dry-cell-battery-diagram.htm
Chemical reaction releases
free electrons.
Electrons travel from the
negative terminal of the cell.
Electrons travel through the
electricity-using device.
Electrons travel back to the
positive terminal of the cell.
Structure of Dry Cells

An electrolyte is a paste or liquid that
conducts electricity, for it contains ions.

The electrolyte reacts with two metals called
electrodes. As a result of this reaction, one
electrode becomes positive, the other negative.

The electrodes are connected to the cell’s
terminals. In the dry cell, electrons leave from
the negative electrode, and return to the
positive electrode.
Most Common Type of Dry Cell

Many types of metals and electrolytes can be
used (e.g., zinc, manganese (IV) oxide, zinc
chloride, and lithium).
An alkaline cell is the most common type of dry
cell because it offers a good combination of:
1. Cost
2. Electricity output
3. Shelf life
4. Reliability
5. Leak resistance

History of the Battery

The 1st battery was created
by Alessandro Volta in
1800.

To create this battery he
used alternating layers of
zinc, blotting paper soaked
in salt water, and silver. This
arrangement was known as
the voltaic pile.
Wet Cells

A wet cell is “wet” because it uses a liquid
electrolyte, which is usually an acid (sulfuric
acid).

Common in motorized vehicles.

Wet cells are generally cheaper and easier
to make than dry cells, but they are not as
safe for they are highly corrosive and may
leak.
How Do Wet Cells Work?
1.
2.
3.
4.
5.
6.
Acidic electrolyte eats away at the zinc (-)
electrode = producing electrons.
Reaction of the electrolyte and copper (+)
electrode does not eat away the copper =
leaves it positive.
Electrons travel along the electrodes (-) to
(+).
Electrons travel out the (-) zinc terminal.
Electrons travel through the wire.
Electrons travel back to the (+) copper
terminal.
Dry Cells vs Wet Cells
Primary vs Rechargeable Cells

The dry cells and wet cells are called primary
cells.

A primary cell is a cell that produces
electricity by means of a chemical reaction that
cannot be reversed.

A rechargeable cell (or a secondary cell)
is a cell that produces electricity by means of a
chemical reaction that can be reversed by using
an external source to run electricity back
through the cell.
Rechargeable Cells

Rechargeable cells are used to start cars,
portable phones and computers.

Only certain electrodes and electrolytes
can be used. Nickel oxide and cadmium is
one combination of chemicals often used
in secondary cells.

Cells can never be fully recharged; they
eventually wear out and die.
Car Battery

How does a car battery work?
http://cheapcarbatteryhouston.com/blog/
Electrochemistry

Electrochemistry is the study of chemical
reactions using electricity.
It can involve:
1. Electrolysis
2. Electroplating
3. Anodizing,
4. Electrorefining.

http://drfus.com/electrochemistry-lab-experience
Electrolysis

Electrolysis is the breaking down of a
substance by an electric current.

It was used to discover new elements and
split water, and eventually led to a new
field of science: electrochemistry.

Many industrial processes use electrolysis
to separate useful elements from
solutions.
Electroplating
https://chemistry58.wikispaces.com/Electroplating

Electroplating is the
use of electricity to
coat a thin layer or
metal on to an object.

This process can
produce cheaper,
stronger, and less
corrosive products.
How Does Electroplating Work?
1.
2.
3.
4.
Needs a liquid electrolyte.
Negative electrode is the
metal that will form the
coating.
Positive electrode is the
object to be plated.
Flow of electrons through
the electrolyte deposits
atoms from the positively
charged metal on to the
negatively charged object.
http://www.explainthatstuff.com/electroplating.html
Other Electrochemical Applications

Anodizing is a process to coat aluminum
parts with a layer of aluminum oxide. This
makes the aluminum much stronger (e.g.,
iPods).

Electrorefining is used to remove
impurities from metals (e.g., AuNO3).
How Does Electrorefining Work?
1.
2.
3.
4.
Need a strong acid electrolyte.
Negative electrode is the impure bar with
gold.
Positive electrode is a pure thin strip of
gold.
Flow of electrons causes the gold from the
impure bar to dissolve and then attach to
the strip of pure gold. It can produce very
pure gold.
Homework

Check and Reflect #2, 4, 5, 6 and 7
(p. 294).