D. A solution of propylene glycol (antifreeze) in the car's radiator has a freezing point of -20°C. What is the molality of the solution?

Match the vapor pressure diagrams with the solute-solvent combinations and explain your answers. a. and b. and c. and d. and

You have read that adding a solute to a solvent can both increase the boiling point and decrease the freezing point. A friend of yours explains it to you like this: The solute and solvent can be like salt in water. The salt gets in the way of freezing in that it blocks the water molecules from joining together. The salt acts like a strong bond holding the water molecules together so that it is harder to boil. What do you say to your friend?

Infer Dehydration occurs when more fluid is lost from the body than is taken in. Scuba divers are advised to hydrate their bodies before diving. Use your knowledge of the relationship between pressure and gas solubility to explain the importance of hydration prior to a dive.

Equal numbers of moles of two soluble, substances, substance A and substance B, are placed into separate 1.0-L samples of water. a The water samples are cooled. Sample A freezes at 0.50C, and Sample B freezes at l.00C. Explain how the solutions can have different freezing points. b You pour 500 mL of the solution containing substance B into a different beaker. How would the freezing point of this 500-mL portion of solution B compare to the freezing point of the 1.0-L sample of solution A? c Calculate the molality of the solutions of A and B. Assume that i = 1 for substance A. d If you were to add an additional 1.0 kg of water to solution B, what would be the new freezing point of the solution? Try to write an answer to this question without using a mathematical formula. e What concentration (molality) of substances A and B would result in both solutions having a freezing point of 0.25C? f Compare the boiling points, vapor pressure, and osmotic pressure of the original solutions of A and B. Dont perform the calculations; just state which is the greater in each ease.

If a substance has a positive enthalpy of solution, which would likely cause more of it to dissolve, hot solvent or cold solvent? Explain.

Explain why the distinction between solute and solvent is not clear for some solutions.