Transcript Chem 116
Monday
February 27, 2012
(Discussion and Worksheet – Electrolytes and Non electrolytes)
Would the light bulb glow in this picture?
Why or why not?
??
Assignment Currently Open Summativ e or Formative Date Issued Date Due Date Into Grade Book Last Day WS – Solubility F 2/15 2/15 QUIZ – SOLUBILITY WS – Types of Mixtures
WS - Solute – Solvent Interactions
WS - Solutes: Electrolytes and Non-electrolytes QUIZ - MIXTURES F S S F F 2/17 2/21 2/22 2/23 2/24 2/17 2/24 2/27 2/28 2/24
Announcements I will be available this afternoon until
4:45 .
Begin Worksheet Electrolytes and Non electrolytes
Solutes: Electrolytes and Non-electrolytes 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 electricity is called an electrolyte.
Solutes: Electrolytes and Non-electrolytes 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 H 3 O + and Cl when dissolved in water.
By contrast, a solution containing neutral solute molecules (such as sugar) does not conduct electric current because it does not contain mobile charged particles.
Solutes: Electrolytes and Non-electrolytes A substance that dissolves in water to give a solution that does not conduct an electric current is called a non-electrolyte.
Sugar is therefore a non-electrolyte.
The picture below shows an apparatus for testing the conductivity of solutions.
Solutes: Electrolytes and Non-electrolytes The electrodes are conductors that are attached to a power supply and that make electrical 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 Non-electrolytes 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 Non-electrolytes For a moderately conductive solution, however, the light bulb is dim.
If the solution is a poor conductor, the light bulb does not glow at all.
Such solutions contain solutes that are non-electrolytes.