Chapter 13 Homework Flashcards
A solution is formed from 1.56 g of an unknown hydrocarbon dissolved in 75.0 g of ethanol. The normal boiling point of ethanol is 78.26°C. With the dissolved hydrocarbon, the solution boils at 78.39°C. What is the molecular weight of the compound?
For ethanol, Kb = 1.22 K kg / mol
194 g / mol
Look at the two graphs that show the deviations in Raoult’s law.
Which of the following correctly correlates the colored plots with their correct solution type?
black: an endothermic solution event
green: an ideal (nonvolatile solute) solution
red: an exothermic solution event
What is the minimum molarity required for sap to rise to the top of a 100.0 m sequoia tree at 25.0°C? Assume that the rising of the sap is due entirely to osmosis, and that the density of the sap is 1.00 g/cm3. The acceleration due to gravity is 9.8 m/s2, the ideal gas constant is 0.0821 L•atm/(mol•K), 1 atm = 1.01 × 105 Pa, and 1 Pa = 1 kg/(m•s2 ).
0.40 M
A gaseous solution is made up of 0.289 moles of nitrogen gas and 0.433 moles of oxygen gas. What are the mole fractions of nitrogen and oxygen, respectively?
0.400 and 0.600
In the context of a liquid-vapor system, what is a dynamic equilibrium?
a condition in which a forward process and its reverse process occur at equal rates so that there is no net change in the amount of either liquid or vapor.
A solution is made by dissolving 50.0 g of glucose (C6H12O6, molar mass = 180.1 g / mol) in 294 g of water. What is the molality of this solution?
0.944 m
Which of the following statements about solutions is not a correct definition for the term named in that statement?
Hydration is the solvation of a solvent by water.
Suppose that you have a 1.23 M solution whose solute has a molar mass of 289.7 g / mol. What is the mass of solute in one liter of the solution?
356 g
Consider the form of Henry’s Law.
Pgas = kHXgas
The value of the Henry’s Law constant is found to be temperature-dependent and generally increases with increasing temperature. This indicates that
gases become less soluble with increasing temperature
Consider water in equilibrium with air. What is the concentration of nitrogen in the water at 25°C if the Henry’s Law constant for nitrogen is 6.48 × 10−4 mol / (L • atm) and if the partial pressure of nitrogen in air is 0.786 atm?
5.09 × 10^−4 M
Suppose you have a flask with some water in it. You add some dichloromethane, CH2Cl2, which separates and forms a second layer below the water. Which statement about this event is not correct?
The mass of dichloromethane that you added is greater than the mass of the water originally present..
Which of the following statements about solutions is not correct?
High solubility in water implies relatively weak bonding between particles.
Suppose you add 3.85 g of naphthalene, C10H8, to 59.2 g of benzene, C6H6. The molar masses of naphthalene and benzene are 128.17 g / mol and 78.0 g / mol respectively. What are the mole fractions of naphthalene and benzene, respectively, in this solution?
0.0380; 0.962
Three vapor pressure curves are plotted against temperature. One for pure water, one for a solvent dissolved in water with molality X, and one of the same solvent dissolved in water to a molality of 2X. Which curve represents the vapor pressure curve for the 2X solution?
D
Suppose that you have oxygen in solution (of water) at 25°C. If the Henry’s law constant = 4.3 × 10^3 atm and the partial pressure of oxygen is 0.22 atm, what is the mole fraction of oxygen in the solution?
5.11 × 10^−5
