Thursday
February 23, 2012
(Solutes: Electrolytes
and Non-electrolytes)
Why does saltwater conduct
electrical current but sugar water
does not?
Saltwater conducts electrical current
because water breaks the salt into
charged ions, which conduct current.
Sugar is broken down into molecules,
.
which do not conduct current
Date
Date Date Into
Issued Due Grade
Book
Assignment
Currently Open
Summativ
e or
Formative
QUIZ – THE IDEAL GAS LAW
AND PHASE CHANGES
S
2/10
2/10
WS – Solubility
F
2/15
2/15
QUIZ – SOLUBILITY
S
2/17
2/17
WS – Types of Mixtures
F
2/21
2/24
WS - Solute – Solvent
Interactions
F
2/22
2/27
2/10
Last
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2/24
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Begin Worksheet
Solutes – Electrolytes &
Non-electrolytes
Solutes: Electrolytes and Nonelectrolytes
• Substances that dissolve in water are classified
according to whether they yield molecules or ions in
solution.
• When an ionic compound dissolves, the positive and
negative ions separate from each other and are
surrounded by water molecules.
• These solute ions are free to move, making it possible
for an electric current to pass through the solution.
• A substance that dissolves in water to give a solution
that conducts electric current is called an electrolyte.
Solutes: Electrolytes and Nonelectrolytes
• Sodium chloride, NaCl, is an electrolyte, as
is any soluble ionic compound.
• Certain highly polar molecular
compounds, such as hydrogen chloride,
HCl, are also electrolytes because HCl
molecules form the ions H3O+ and Cl−
when dissolved in water.
• By contrast, a solution containing neutral
solute molecules does not conduct electric
current because it does not contain mobile
charged particles.
Solutes: Electrolytes and Nonelectrolytes
A substance that dissolves in water to give a solution
that does not conduct an electric current is called a
non-electrolyte.
Sugar is a non-electrolyte.
The picture below shows an apparatus for testing the
conductivity of solutions.
Solutes: Electrolytes and Nonelectrolytes
The electrodes are conductors that are attached to a
power supply and that make electric contact with the
test solution.
For a current to pass through the light-bulb filament,
the test solution must provide a conducting path
between the two electrodes.
Solutes: Electrolytes and Nonelectrolytes
A non-conducting solution is like an open switch
between the electrodes, and there is no current in the
circuit.
The light bulb glows brightly if a solution that is a good
conductor is tested.
Such solutions contain solutes that are electrolytes.
Solutes: Electrolytes and Nonelectrolytes
For a moderately conductive solution, however, the
light bulb is dim.
If a solution is a poor conductor, the light bulb does
not glow at all.
Such solutions contain solutes that are non-electrolytes.
Complete Worksheet
Solutes – Electrolytes &
Non-electrolytes