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$Math Mysteries - Measurement$

Teacher Page KEY Temperature ( 0 C) Directions: Answer in complete sentences and show all work for calculations. 1. What relationship exists between solubility and temperature for most of the substances shown? A direct relationship is shown for most substances, as temperature increases the solubility of most substances increases. 2. What is the exception? The exception is gas solubility. Gases are less soluble at higher temperature, illustrating an indirect relationship 3. What explains why solids become more soluble as temperature increases and why gases become less soluble? Use the following words to help justify your response: temperature, collisions and energy. As temperature increases both speed of the water molecules and the number of collisions increase. A solid remains dissolved by the continual motion of the eater molecules. The more energy and motion, the more particles that can remain in solution. This is especially true for ionic compounds, because water is polar and the opposite charges help stick the water molecules to the ions. Gases are often nonpolar and they have very low boiling points, so as temperature increases they tend to “boil away”. That is why a soda will go flat much faster if it is left in a warm place. 4. Which is more soluble NaNO 3 or KCl? Does the temperature matter? Why or why not? NaNO 3 because the higher line indicates that more NaNO 3 can be dissolved at ALL temperatures. 5. How does the line drawn for a particular substance relate to the saturation of a solution of that substance? Use the following words to help justify your response: saturated, unsaturated, supersaturated. The line marks the saturation point of a solute in 100 grams of water. If you have less grams dissolved than indicated by the line then your solution is unsaturated at that temperature. If you have more, then your solution is supersaturated at that temperature. 6. How many grams of NH 4 Cl will dissolve in 100. grams of water at 90. 0 C? 72 grams 7. How many grams of KClO 3 will dissolve in 300. grams of water at 30. 0 C? 300. g of H 2 O X 10. g KClO 3 = 30. g KClO 3 100. g H 2 O 8. How would you make a saturated solution of KNO 3 at 60. 0 C in 50. grams of water? The graph indicates that that 106 grams of KNO 3 will dissolve in 100. grams of water, so I need only 106g /2= 53 grams of KNO 3 to make the solution. So I would measure out 50 grams of water and 53 grams of KNO 3 and mix them together to make the solution. 9. If you were asked to make a saturated solution of KCl in 100. grams of water, what other piece of information would you need to before you could start? Why? You would need to know the temperature of the solution. The saturation point is very different depending on the temperature 10. If you start with a saturated solution of NH 3 in 100. grams of water at 10. 0 C, how many grams of NH 3 gas would bubble out of solution if you raise the temperature to 80. 0 C?
100. grams of water at 10. 0 C can hold 70. grams of NH 3 . 100. grams of water at 80.0C can hold 14 grams of NH 3 . So 70. g -14 g = 56 grams of NH 3 will bubble out. Teacher Page 11. A saturated solution of NaNO 3 was made with 300. grams of water at 40. 0 C. How much NaNO 3 could be recovered by evaporating the solution to dryness? So 300. grams of water can hold 3 X 106 g = 318 g NaNO 3 will be recovered. 12. A saturated solution KNO 3 in 400. grams of water at 50. 0 C is cooled to 10. 0 C. How much KNO 3 will come out of solution as crystals? From the graph 100. grams of water at 50. 0 C can hold 83 g of KNO 3 So 400. grams of water can hold 4 X 83 g = 332 g KNO 3 From the graph 100. grams of water at 10. 0 C can hold 21 g of KNO 3 So 400. grams of water can hold 4 X 21 g = 84 g KNO 3 As the solution is cooled 332 g- 84g = 248 g KNO 3 will form crystals. 13. You start with 200. grams of ice saturated with SO 2 at 0. 0 C. How many grams of SO 2 will bubble out of solution if you melt the ice and raise the temperature of the water to 80. 0 C? From the graph 100.g of ice at 0. 0 C can hold 23 g of SO 2 So 200. grams of ice can hold 2 X 24 g = 48 g SO 2 From the graph 100g. of water at 80. 0 C can hold 4 g of SO 2 So 200. grams of water can hold 2 X 4g = 8 g of SO 2 As the solution is heated 48 g – 8 g = 40 g of SO 2 will bubble out.
Page 1: Teacher page Chemistry I EQ: Why do

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