2003 Virginia SOLs
Motivation for Learning
Discuss with students the history of borax as given in the background information.
Borax is sodium tetraborate. It dissolves in water forming an alkaline, antiseptic solution that is used as a water softener, disinfectant, detergent and welding flux. Historically, many ancient people found valuable uses for borax. The Egyptians used borax in mummification while the Romans used it for glass making. Marco Polo's caravans transported it from Tibet to Europe in the 13th century.
Borax was a rare commodity until lake bed deposits were found in California in the 1850s. The most famous commercial borax mining operations were located in Death Valley in California in the 1880s. Borax was recovered by dissolving "cotton balls" made up of borate minerals in boiling water. As the solution cooled the borax precipitated out. To get the borax to market was a165 mile journey through the hot desert to the nearest railroad. Up to ten tons of borax was carried on giant wagons that were pulled by teams of 18 mules and 2 draft horses - the famous "20-mule teams." These teams averaged two miles an hour; as a result the round trip took 30 days to complete. Click here for more information about the history of borax mining in Death Valley.
Notes to the Teacher: Mule Team Borax can be purchased at the grocery store in the section near bleach and detergents. Borax is potentially toxic to humans and pets, if ingested in large amounts. Students should wear safety goggles and wash hands thoroughly after contact.
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Part I - Making a pipe cleaner ornament
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|Initial Mass of Borax + Beaker||Final Mass of Borax + Beaker||Initial Mass - Final Mass = Total Mass of Borax Added||Solubility = Borax (g)/water (ml)|
|Tap Water (~ 200C)|
|Warm Water (~400C)|
|Hot Water (~600C)|
|In the space above, graph the temperature of the solution versus the solubility of the borax. Use the y-axis for tempertature and the x-axis for solubility.|
Students with Special Needs
Each student should be able to participate in this activity.
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1. How does temperature affect the solubility of a substance?
2. In this experiment, what was the solvent and what was the solute?
3. From your graph, how much borax would dissolve in 700 ml of water heated to a temperature of 50 0C?
4. From your graph, what temperature of water is required to dissolve 25 grams of borax?
5. If you were to make a borax solution for cleaning, would you use cold or warm water? Explain your answer.
6. At what point in your experiment was the solution unsaturated, saturated, and supersaturated?