Skip to main content
Pearson+ LogoPearson+ Logo
Ch.13 - Properties of Solutions
All textbooksBrown 14th EditionCh.13 - Properties of SolutionsProblem 66
Previous problem
Next problem
Chapter 13, Problem 66

(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.

Verified step by step guidance
1
Step 1: Use Raoult's Law to determine the change in vapor pressure. Raoult's Law states that the vapor pressure of a solvent in a solution (P_solution) is equal to the mole fraction of the solvent (X_solvent) times the vapor pressure of the pure solvent (P_pure). The change in vapor pressure (ΔP) is given by ΔP = P_pure - P_solution.
Step 2: Calculate the vapor pressure of the ethanol solution. Since the vapor pressure is reduced by 10.0 torr, the vapor pressure of the solution is P_solution = P_pure - 10.0 torr, where P_pure is 1.00 x 10^2 torr.
Step 3: Determine the mole fraction of ethanol in the solution. Rearrange Raoult's Law to find the mole fraction: X_ethanol = P_solution / P_pure.
Step 4: Calculate the moles of ethanol. Use the molar mass of ethanol (C2H5OH), which is approximately 46.08 g/mol, to convert the mass of ethanol (1.00 kg) to moles.
Step 5: Use the mole fraction to find the moles of ethylene glycol needed. The mole fraction of ethanol is related to the moles of ethanol and ethylene glycol by X_ethanol = moles_ethanol / (moles_ethanol + moles_ethylene_glycol). Solve for moles_ethylene_glycol and then convert to mass using the molar mass of ethylene glycol (C2H6O2), which is approximately 62.07 g/mol.
Previous problem
Next problem
Related Practice
Open Question
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.
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?
2653
views
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.)
Textbook Question

At 63.5 °C, the vapor pressure of H2O is 175 torr, and that of ethanol (C2H5OH) is 400 torr. A solution is made by mixing equal masses of H2O and C2H5OH. (a) What is the mole fraction of ethanol in the solution?

2059
views
Textbook Question

At 63.5 °C, the vapor pressure of H2O is 175 torr, and that of ethanol (C2H5OH) is 400 torr. A solution is made by mixing equal masses of H2O and C2H5OH. (b) Assuming ideal solution behavior, what is the vapor pressure of the solution at 63.5 °C?

703
views
Textbook Question

At 20 °C, the vapor pressure of benzene (C6H6) is 75 torr, and that of toluene (C7H8) is 22 torr. Assume that benzene and toluene form an ideal solution. (b) What is the mole fraction of benzene in the vapor above the solution described in part (a)?

2271
views
1
comments