Questions: What are freezing points?
At what temperature does water freeze?
Can we chemically change matter into another physical state?
Materials: 3 empty jars
1 jar filled with salt (sodium chloride)
3 glass test tubes
3 measuring spoons
Ice
3 thermometers
Paper and Pencil
Procedures:
1.) You will work in groups of two/three. Carefully unwrap glass test tubes. Place thermometer in jar with numbers facing outside (you will need to be able to read this!!)
2.) Send one person per group with thermometer filled jar (thermometer should be against the jar) to front of room. Fill jar ¾ way with ice. Send another group member to the sink and fill test tube ¼ way with water.
3.) In glass jar, make a “well” in the center (shift ice around to make a hole) and gently place glass test tube in the center. (Ice should surround test tube and hold it in place.)
4.) Record the temperature of ice jar (both Fahrenheit and Celsius).
5.) Add one tablespoon of salt over the top of ice in jar. (Do not put salt in test tube.) Record temperature (both Fahrenheit and Celsius) and your observations.
6.) Repeat steps 4 and 5 until test tube is frozen.
7.) What did you observe? What happened? Why? Explain.