http://www.ck12.org Chapter 15. Water
- Construct a diagram showing what happens on the molecular level when the following substances are added
to water:
a. A soluble compound that dissociates into ions
b. A soluble compound that does not dissociate into ions
c. An insoluble compound - You mix 50 mL of pure water with 30 mL of 95% ethanol and stir until a completely homogeneous mixture is
produced. You then measure the new volume of the solution.
a. What might you expect the new volume to be?
b. When you put the solution into a graduated cylinder, you see that it has a volume of 76 mL. What might
be your explanation for this? - Can you think of substances that are soluble in water under some circumstances but not others?
- Dirt that gets on our hands can be difficult to remove by rinsing with cold water. What are some things that
you can do to increase the solubility of dirt, making it easier to dissolve in running water? - Can you think of an example in which water is the solute instead of the solvent?
Further Reading / Supplemental Links
- PhET Dissolving Animation: http://phet.colorado.edu/en/simulation/soluble-salts
- Solubility and solubility rules: http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch18/soluble.php
- Practice quiz on solutions: http://www.chem4kids.com/extras/quiz_mattersolution/index.html
Points to Consider
- Some substances only partially dissociate into ions when dissolved in water. How might you test to see the
degree to which a substance has dissociated? - Can you think of a substance that only partially dissolves in water?
- How can you improve water’s ability to dissolve a substance?