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CHAPTER 12 BASIC HOMEWORK (Go to Chapter 13 Explanation Provided) Click Here

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Question 1

What is the molarity of a sodium chloride solution, if 13.28 g of NaCl are dissolved in enough water to make 0.500 L of solution? 

Correct

 

Explanation

 

 

Question 2

What is the molality of a sodium chloride solution, if 11.12 g of NaCl are dissolved in 0.700 kg of water? Hint given in general feedback 
Correct


 

Explanation

 

Question 3

What is the mole fraction of a lithium fluoride solution prepared by dissolving 38.5 g of LiF in 0.800 kg of water. Hint given in general feedback
Correct

 

Explanation

 

Question 4

What is the mass percent of a lithium fluoride in a solution prepared by dissolving 37.0 g of LiF in 0.700 kg of water. Hint given in general feedback

Correct

 

Explanation

 

Question 5

Calculate the freezing point for a 1.55 m solution of CCl4 in benzene.

Help: Solution freezing point

Correct

 

Explanation

 

 

Question 6

Calculate the increase in the boiling point,ΔT, for a 1.35 m solution of sucrose (dissolves as a molecule) in water.

Correct

 

Explanation

 

 

Question 7

Sugar is dissolved in hot water at 45oC until the mole fraction of water decreases to 0.896. The vapor pressure of pure water at this temperature is 72 torr. What is the vapor pressure (in torr) of water for this solution?

Help: Colligative properties of gases

Correct

 

Explanation

 

 

Question 8

18.0 g of the nonvolatile solute urea (M.W. = 60.06 g/mol) is dissolved in 194 g of water at 60oC. The vapor pressure of pure water at this temperature is 149 torr. What is the equilibrium vapor pressure (in torr) of water for this solution? 

Hint given in general feedback.
Correct

 

Explanation

 

Question 9

Which 0.06 m aqueous solution (in water) should have the greatest increase in boiling point? 
Select one:
 Correct

 

Explanation

 

 

Question 10

Calculate the freezing point for a 4.20 m aqueous solution of NaCl. 

Correct

 

Explanation

 

 

Question 11

A 0.200 g sample of a nonvolatile yellow crystalline solid is dissolved in 15.1 g of benzene, producing a solution that freezes at 5.01oC. Find the molar mass of the yellow solid in g/mol. 

Correct

 

Explanation

 

 

Question 12

A 2.60 g sample of a nonvolatile nonelectrolyte blue crystalline solid is dissolved in 47.1 g of acetic acid, producing a solution that bolis at 119.6oC. Find the molar mass of the blue solid in g/mol.

Hint given in feedback

Correct

 

Explanation

 Use the same procedure as in the last problem except now ΔTb = mkb.

 

Question 13

At a certain temperature the vapor pressure of pure benzene and pure toluene are 380 torr and 130 torr, respectively. If the mole fraction of benzene is 0.42, what is the total vapor pressure.

Help: Vapor pressure ideal liquids

Correct

 

Explanation

 

 

Question 14

At a certain temperature the vapor pressure of pure benzene and pure toluene are 380 torr and 130 torr, respectively. If 2.60 mol benzene is mixed with 4.76 mol toluene, what is the total vapor pressure.

Correct

 

Explanation

 

 

Question 15

Which of the following pairs of molecules are expected to obey Raoult's law? 
Select one or more:
 Correct
 Correct
 Correct

 

Explanation

 

 

Question 16

What is the osmotic pressure in atm of a 0.870 M solution of sugar at 25oC?

Help: Osmotic pressure

Correct

 

Explanation

Did you remember to use K?

 

Question 17

What is the osmotic pressure in atm of a 0.183 M solution of NaCl at 0oC? 

Hint given in feedback
Correct

 

Explanation

 You must use the molarity of particles. Remember NaCl is a strong electrolyte. This is equivalent to π = (Mi)RT where i is the van't Hoft factor.

Because NaCl is a strong electrolyte it breaks apart into Na+ ions and Cl- when it dissolves in water. Thus each NaCl produces two particles when dissolved in water and the van't Hoff factor is 2.

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