Colligative Properties
Date: November 6th, 2012
Homework: Solution Concentration Worksheet
On Tuesday we learned about Colligative properties. Colligative properties depend only on the number of solute particles present, not on the type of particle it is. We see Colligative properties in things such as boiling points and melting points.
Our first demo showed how water reacts when other particles are added to the solution. In this demo, the students represented water and the objects in hand represented the other particles.
First the water moves freely. When a particle is added, some of the water is attracted to that particle.
Then, more particles are added to the water and less of the water moves freely.
Finally when more particles are added, the water is the water is attracted to the particle and less water can escape.
When more water is "linked", it doesn't escape and not attracted to pure solvent. The vapor pressure goes down.
The other demo we had today was a bottle of soda flash freezing. Salt was sprinkled on ice with soda in the ice. The ice had a lower freezing point and was able to cool the drink to a lower temperature without freezing it. When the soda was opened, the pressure decreased because the CO2 escaped. This resulted in the flash freezing.
THE NEXT SCRIBE WILL BE..............Megan N.
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