Chemistry TEKS 2D Organize, analyze, evaluate, make inferences, and predict trends from data. Students will be able to collect data, organize into a data table and construct a graph by the time they reach the high school science courses. If they are having difficulty they should review elementary expectations for students. The graphs used in Chemistry can be generated from labs or drawn from data collected through research. The analysis of the graphs can be from very simple extrapolation of data from the graph to prediction of trends. The graph shown below was taken from Glencoe Physical Science. Data such as this could be collected through research or by conducting a solubility lab in the classroom. Formula 0 C 20 C 60 C 100 C KBr 53.6 65.3 85.5 104 NaCl 35.7 35.9 37.1 39.2 KNO 3 13.9 31.9 109 245 Solubility (grams per 100 g of water) 0 50 300250200150100 Solubility KBrNaCl KNO3 0 C 20 C Temperature ( C) Questions this graph could generate: For which substance does the solubility increase the least? What is the solubility of KBr at 60 C? What do you predict the solubility of NaCl to be at 110 C? 60 C 100 C
Solubility Teacher Information O Graphs, Charts, and Tables Chemistry Students will be able to collect data, organize into a data table and construct a graph by the time they reach the high school science courses. If they are having difficulty, they should review elementary expectations for students. Science TEKS c2c Organize, analyze, evaluate, make inferences, and predict trends from data. 12 The student knows the factors that influence the solubility of solutes in a solvent. Sample Data: Test Tube Temperature ( C) Solubility (g/100 g 2 0) 1 25.5 40 2 47.2 80 3 64 120 4 76.4 160 The students should take this data and make a best-fit curve.
Solubility O Problem: Calculate the solubility of potassium nitrate at various temperatures. ypothesis: (Read the problem and procedures and form a hypothesis.) Materials: hot plate 10-mL graduated cylinder thermometer 400-mL beaker test tube rack ring stand 4 test tubes stirring rod distilled water 20 g potassium nitrate KNO 3 triple beam balance Procedures: 1. Wear goggles throughout lab. 2. Label the test tubes 1 4 and place in test tube race. Measure out 2.0 g of KNO 3 and place in test tube 1. Measure out 4.0 g of KNO 3 and place in test tube 2. Measure out 6.0 g of KNO 3 and place in test tube 3. Measure out 8.0 g of KNO 3 and place in test tube 4. 3. Measure out exactly 5.0 ml distilled water and place in each test tube. 4. Fill the 400 ml beaker about three-fourths of water, to use as a water bath. Place it on a hot plate. eat the water to about 90 C and maintain this temperature. (Attach the thermometer to the ring stand so it doesn t touch the bottom of the beaker.) 5. Using a utility clamp attach test tube 1 to the ring stand. Lower it into the water. Use the stirring rod to stir the mixture until the KNO 3 is completely dissolved.
6. Remove the test tube from the water bath and place in the test tube rack. 7. Dry off the thermometer; place in the test tube rack. Look for the first signs of crystallization. Record the temperature to the nearest.1 C. 8. Repeat step 5-7 for test tubes 2 4. (The temperature of the water bath may have to be increased for test tubes 3 and 4.) 9. Time savers: Test tubes 1 and 2 can be placed in a cool tap water bath in the 250-ml beaker to drop the temperature more quickly. If the crystallization occurs too quickly briefly warm the test tube in the hot water bath to redissolve. One lab partner can be stirring for dissolving and the other watches for crystallization. Analysis: Solubility is the mass of solute that will dissolve in 100 g of water at a specified temperature. In this lab, 5 ml of water was used (assume 1.0 g/ml of water). Take the collected data make it proportional to get the solubility of the KNO 3. Graph temperature vs. solubility using a best-fit curve. What is the relationship between solubility and temperature? Using your graph predict what the solubility would be at 50 Conclusion:Discuss the experiment, hypothesis, any discovered relationships, and any changes you could make to this experiment if you were to do it again.
Student Graph Example T Temperature in Celcius 90 80 70 60 50 40 30 20 10 0 40 80 120 160 Solubility (g/100g 2O)