Case Study Of Lab: I Scream For Colligative Properties

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Lab: I Scream, We All Scream for …Colligative Properties!? Introduction: When a solute is added to water the physical properties of freezing point and boiling point change. Water normally freezes at 0oC and boils at 100oC. As more solute is added, the freezing point drops (“freezing point depression”) and the boiling point increases (“boiling point elevation”). This property is useful in our lives. Antifreeze is added to car radiators to keep the water used as a coolant from freezing in winter and boiling in the summer. Antifreeze is added to a solvent to “de-ice” planes before take-off to prevent ice forming on the wings. When roads ice over in the winter, salt is added along with sand. The sand is used to give cars traction and the salt…show more content…
Use your textbook (pp. 471-475) to answer the pre-lab questions below. Define COLLIGATIVE PROPERTIES: Give four examples of COLLIGATIVE PROPERTIES 1. 2. 3. 4. Increasing the concentration of a solution will __________ the boiling point of the solution Increasing the concentration of a solution will __________ the freezing point of the solution Procedure: (BE SURE TO RECORD ANY OBSERVATIONS!) 1. Measure 1/2 cup (c) milk and 1/2 c whipping cream; put into a small Zip-lock baggie. 2. Add 1/4 tsp. vanilla to the milk/cream mixture. 3. Measure 1/4 c sugar; add to milk/cream mixture in baggie. 4. Close the bag SECURELY, squeezing most of the air out before sealing. 5. Place the small plastic bag inside a larger Zip-lock baggie. 6. Surround the smaller bag with a few cups of crushed ice. 7. Pour 3/4 to 1 c salt over the crushed ice and seal the larger bag SECURELY. 8. Put on mittens or wrap the bag in a thick towel. Knead or roll back and forth on the lab table. Be careful not to put too much pressure on the bag. 9. After 10 minutes, see if the mixture is frozen. If not, continue kneading. 10. When the mixture is frozen, remove the smaller bag. Wipe the brine from the zipped edges of the…show more content…
Where did the heat the flow from (What happened to the temperature of the ice after salt was added?) 3. What is the minimum temperature that pure water can exist as a liquid at standard pressure? 4. What do you think would happen to the temperature of the ice if you added 6 tablespoons of salt instead of 2 tablespoons? 5. If there are charged particles that can move around in a substance, that substance is able to conduct electricity. So, do ionic compounds or covalent compounds conduct electricity when dissolved in water? Explain. Use the idea of what happens when these two different types of compounds dissolve in water in your answer. 6. Which compound types (ionic or covalent) produce more particles when dissolved in water and why? 7. Answer the following questions: How many particles are produced when a mole of sugar dissolves? _______ How many particles are produced when a mole of CO2 dissolves? _______ How many particles are produced when a mole of sodium chloride (NaCl) dissolves? _____ How many particles are produced when a mole of copper (II) chloride (CuCl2 ) dissolves? _____ How many particles are produced when a mole of iron (III) sulfate [Fe2(SO4)3] dissolves?