Textbook Question
You make a solution of a nonvolatile solute with a liquid solvent. Indicate if each of the following statements is true or false. (a) The freezing point of the solution is unchanged by addition of the solvent.
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Ch.13 - Properties of Solutions
Chapter 13, Problem 63
Consider two solutions, one formed by adding 10 g of glucose (C6H12O6) to 1 L of water and the other formed by adding 10 g of sucrose (C12H22O11) to 1 L of water. Calculate the vapor pressure for each solution at 20 °C; the vapor pressure of pure water at this temperature is 17.5 torr.
Verified step by step guidance1
Step 1: Calculate the molar mass of glucose (C6H12O6) by adding the atomic masses of its constituent atoms: 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms.
Step 2: Calculate the number of moles of glucose by dividing the mass of glucose (10 g) by its molar mass.
Step 3: Calculate the molar mass of sucrose (C12H22O11) by adding the atomic masses of its constituent atoms: 12 carbon atoms, 22 hydrogen atoms, and 11 oxygen atoms.
Step 4: Calculate the number of moles of sucrose by dividing the mass of sucrose (10 g) by its molar mass.
Step 5: Use Raoult's Law to calculate the vapor pressure of each solution. Raoult's Law states that the vapor pressure of the solution is equal to the mole fraction of the solvent multiplied by the vapor pressure of the pure solvent. Calculate the mole fraction of water in each solution and then use it to find the vapor pressure.
Related Practice
Textbook Question
You make a solution of a nonvolatile solute with a liquid solvent. Indicate if each of the following statements is true or false. (b) The solid that forms as the solution freezes is nearly pure solute.
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Textbook Question
You make a solution of a nonvolatile solute with a liquid solvent. Indicate if each of the following statements is true or false. (d) The boiling point of the solution increases in proportion to the concentration of the solute.
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Textbook Question
The vapor pressure of pure water at 60 °C is 149 torr. The
vapor pressure of water over a solution at 60 °C containing
equal numbers of moles of water and ethylene glycol (a
nonvolatile solute) is 67 torr. Is the solution ideal according to Raoult's law?
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Open Question
(a) Calculate the vapor pressure of water above a solution prepared by adding 22.5 g of lactose (C12H22O11) to 200.0 g of water at 338 K. (Vapor–pressure data for water are given in Appendix B.)
Open Question
(b) Calculate the mass of ethylene glycol (C2H6O2) that must be added to 1.00 kg of ethanol (C2H5OH) to reduce its vapor pressure by 10.0 torr at 35 °C. The vapor pressure of pure ethanol at 35 °C is 1.00 x 10^2 torr.