Name: ___________________ Chemistry: Solubility and Supersaturation Lab Purpose: To prepare a supersaturated solution of sodium sulfate and observe the effect of seeding the supersaturated solution. Materials: 1 medium test tube, 1 test tube rack, 1 test tube holder, one 100mL beaker, two 400mL beakers, one 10mL graduated cylinder, stirring rod, hot plate, sodium sulfate decahydrate, ice, water. Procedure: As you perform the experiment, record your observations in the data table. 1. Make a water bath by filling the 400mL beaker with approximately 200mL of water. Place the beaker on the hot plate and turn the hot plate on medium heat. Do not let the water boil. 2. Place 2.5g of sodium sulfate decahydrate in the test tube. Add 10mL of water. 3. Place the test tube in the water bath until the entire solid has dissolved. Agitate the mixture gently by stirring with a stirring rod. 4. While the test tube is heating, make an ice bath by ½ filling a 400 mL beaker with ice and then filling the beaker with water. 5. When the entire solid in the hot water bath has dissolved, place the test tube in the test tube holder and remove the test tube from the water bath. Add one more crystal of NaSO4 . 10 H2O to the test tube and gently agitate. Record your observations in the data table. Was the solution unsaturated, saturated, or supersaturated? 6. Place the test tube in the ice bath. Be careful not to disturb the test tube during the cooling process. If crystals begin to form during the cooling process reheat the test tube to re-dissolve the crystals. Leave in ice bath until test tube is cold (approximately 5 minutes). 7. When the solution is cold, gently remove the test tube from the ice bath and put it in the test tube rack. 8. Add one small crystal of NaSO4 . 10 H2O to the test tube. Describe what you see in the data table. 9. Reheat the test tube to dissolve the crystals. When crystals have dissolved, pour the contents down the sink and rinse your test tube out with water. Return the test tube to the test tube rack. 10. Clean up your table. Data/Observations: Step 5

Step 8

Name: ___________________ Analysis Questions: 1. Why is it necessary to heat the mixture in step 3?

2. At the end of step 4 was the solution unsaturated, saturated, or supersaturated? Explain your answer.

3. At the end of step 6 was the solution unsaturated, saturated, or supersaturated? Explain your answer.

4. At the end of step 8, when crystallization is complete, was the solution unsaturated, saturated, or supersaturated? Explain your answer.

5. Describe a simple test to determine whether a solution is unsaturated, saturated or supersaturate. Explain how to interpret the test. (Hint: think about this lab)