Colligative Properties

Colligative Properties are properties of substances such as vapor pressure lowering, boiling point elevation,melting point depression, and osmotic pressure. The main ones we will focus on is boiling point elevation and melting point depression. Also, these properties are only changed by the number of solute particles, not by the identity of the solute.

Boiling Point Elevation

The boiling point elevation property is simply this, ΔTb(subscript) = Kb(subscript) x m. ΔTb is added to the normal boiling point to get the new boiling point. Kb is the constant which will be given to you. m is the molality. That is how you figure out the boiling point when adding one substance to another.

Freezing Point Depression

The freezing point depression property is, ΔTf(subscript) = Kf(subscript) x m. The symbols in the equation meant the same thing as above. Again, the constant (Kf) will be given to you in problems. Below is an experiment that we did in class. First, Club Soda was chilled to about -8 degrees Celsius. This was done by adding normal table salt to ice making the freezing point of the water go way down, this enabled the water and ice to get very cold. Then when the Club Soda was removed from the water the bottle was opened to release the carbon dioxide and flash freeze the soda.

HW: Solution Concentration WS

The next scribe is: Jake A.