<p>Chemistry Name : Lab - Supersaturation Date :</p><p>A. Purpose :To prepare a supersaturated solution of a salt and observe the effect of adding a small seed crystal to it.</p><p>B. Materials safety goggles 1 gas burner 1 medium test tube centigram balance 1 test-tube rack sodium sulfate decahydrate, Na2SO4 • 10H2O 1 test-tube holder ice 1 100-mL beaker distilled water 1 10-mL graduated cylinder </p><p>C. Procedure :</p><p>1. Place 5 g of Na2SO4 • 10H2O in a clean medium-sized test tube. Add 10 mL of distilled water. 2. Hold the test tube in a test-tube holder and heat it in a burner, agitating the mixture gently until all of the solid has dissolved. CAUTION: When heating a test tube, never point the mouth of the tube at yourself or anyone else. Place the test tube in a test-tube rack. Add one more crystal of Na2SO4 • 10H2O to the warmed solution and gently agitate it. Record your observations in Data Table 1. 3. Place the test tube and contents in a beaker of ice water to cool. Be careful not to disturb the test tube during the cooling process. If crystals begin to form as the tube is cooling, reheat the tube to redissolve the crystals and cool the tube again. 4. When the solution is cold, gently remove the tube from the ice water bath and put it in the test- tube rack. Add one small crystal of Na2SO4 • 10H2O. Describe what you see. Touch the bottom of the test tube to the palm of your hand. Record your observations in Data Table 1. 5. Follow your teacher’s instructions for the proper disposal of the materials.</p><p>D. Obervations</p><p>DATA TABLE 1: OBSERVATIONS Step Observations 2</p><p>4</p><p>E. Analyses</p><p>1. Why is it necessary to heat the mixture in Step 2 of the procedure? 2. Is the solution unsaturated, saturated, or supersaturated at the end of Step 2? Explain. 3. Is the solution unsaturated, saturated, or supersaturated at the end of Step 3? Give evidence for your answer. 4. At the end of Step 4, when crystallization is complete, is the solution unsaturated, saturated, or supersaturated? Explain. 5. Describe a simple test to determine whether a solution is unsaturated, saturated, or supersaturated. Explain how to interpret the test.</p>