Lesson 18 notes

Changing Mixtures

1. Properties of individual components of mixtures have the following:

A solid, colored solute is added to water, the solution produced can have some of the properties of both the solute and the solvent.

- Examples: copper sulfate (both the solvent and solute become the same color), potassium permanganate (both the solvent and the solute become the same color)

- It is a clear liquid and it is colored.

2. Properties of mixture are often very different from those of individual components.

-varying the quantities of each substance added to a mixture can affect the behavior of the mixture in unexpected ways.

-you will see what happens to the behavior of the temperature of water when salt is added to it. (lowers the melting point, more salt results in still lower melting point)

3. Melting point depressions results from the ability of solute particles to interfere with the formation of solvent crystals.

- methanol boils at 65 degree C

4. The change in the melting point of a solvent is directly proportional to the amount of solute in the mixture. The more solute added to the solvent the greater the behavior difference.

5.The boiling point of water rises when salt is added to water.

-Boiling point elevations takes place because solute particles interfere with evaporation of a solvent.

-In the case of aqueous solutions, solutes that are more volatile than water do not elevate the boiling point. (52 degree C)

6. Boiling point elevations and melting point depressions have several applications.

-antifreeze for cars (ethylene glycol)

-coolant to operate at temperatures above the boiling point of water.