MHS Chemistry
Identifying an Unknown by Solubility
The purpose of this activity is to remind ourselves of solution concepts while determining the identity of an unknown chloride based on its solubility.
1. Define the following words:
Solution
Solute
Solvent
Concentration
Solubility
Saturated
Salt
2. Look up the following compounds in the CRC Handbook of Chemistry & Physics, or Lange's Handbook of Chemistry. Look for a table called "Physical Constants of Inorganic Compounds" or something similar (the title varies slightly depending on the edition). Fill in the table below. For solubility, use the one listed for "cold water."
| Name | Formula | Color | Solubility | unit of measure |
| Cesium Chloride | ||||
| Lithium Chloride | ||||
| Potassium Chloride | ||||
| Rubidium Chloride | ||||
| Sodium Chloride |
3. Make a graph of the solubility as a periodic trend. (What was your dependent variable? Your independent variable?)
4. How can you recognize a saturated solution in a test tube?
5. Make one test-tube-full of a saturated solution of the unknown provided.
6. What is the relationship between the words "solubility" "saturated" and "concentration"?
7. With your partner, develop a procedure to determine the concentration/solubility of your saturated solution. Hint: figure out what measurements you would need in order to calculate this.
8. Based on your graph (#3), what substance is your unknown most likely to be? Show your explanation/work on the graph.
9. Discuss one possible source our error in your data that might lead to your results not exactly matching any of your "knowns" measurements. How did this error influence your results? Remember that this can not include problems with your own sjill at recording data.