Question 1

Liquid A has vapor pressure x. Liquid B has vapor pressure y, and x > y. What is the mole fraction of A in the liquid mixture if the vapor above the solution is 30% A?

Accepted Answer

A)  0.7x/(0.7x + 0.3y) 
B)  0.3x/(0.3x + 0.7y) 
C)  0.7y/(0.3x + 0.7y) 
D)  0.3y/(0.7x + 0.3y) 
E)  none of these 
A)  0.7x/(0.7x + 0.3y) 
B)  0.3x/(0.3x + 0.7y) 
C)  0.7y/(0.3x + 0.7y) 
D)  0.3y/(0.7x + 0.3y) 
E)  none of these

Question 2

A solution of two liquids, A and B, shows negative deviation from Raoult's law. This means that

Accepted Answer

A)  the molecules of A hinder the strong interaction between B molecules. 
B)  molecules of A interact strongly with other A-type molecules. 
C)  molecules of A interact more strongly with B than with A or and more strongly than B with B. 
D)  the two liquids have a positive heat of solution. 
E)  molecules of A interact weakly, if at all, with B molecules. 
A)  the molecules of A hinder the strong interaction between B molecules. 
B)  molecules of A interact strongly with other A-type molecules. 
C)  molecules of A interact more strongly with B than with A or and more strongly than B with B. 
D)  the two liquids have a positive heat of solution. 
E)  molecules of A interact weakly, if at all, with B molecules.

Question 3

The destruction of a colloid is called

Accepted Answer

A)  denaturation. 
B)  reconfiguration. 
C)  coagulation. 
D)  degeneration. 
E)  none of these 
A)  denaturation. 
B)  reconfiguration. 
C)  coagulation. 
D)  degeneration. 
E)  none of these

Question 4

Which of the following will cause the calculated molar mass of a compound determined by the freezing-point depression method to be greater than the true molar mass?

Accepted Answer

A)  While adding the solute, the technician spilled some of it on the lab bench. 
B)  Water gets into the solvent after the freezing point of the pure solvent is determined. 
C)  Some of the solute molecules break apart. 
D)  The mass of solvent is smaller than determined from the weighing. 
E)  all of these 
A)  While adding the solute, the technician spilled some of it on the lab bench. 
B)  Water gets into the solvent after the freezing point of the pure solvent is determined. 
C)  Some of the solute molecules break apart. 
D)  The mass of solvent is smaller than determined from the weighing. 
E)  all of these

Question 5

When a 19.4-g sample of an unknown compound is dissolved in 458.0 g of benzene, the freezing point of the resulting solution of 3.82°C. The freezing point of pure benzene is 3.86°C, and Kf for benzene is 5.12°C/m. Calculate the molar mass of the unknown compound.

Accepted Answer

A)  7.47 × 103 g/mol 
B)  5.62 × 101 g/mol 
C)  9.34 × 102 g/mol 
D)  2.81 × 101 g/mol 
E)  1.34 × 102 g/mol 
A)  7.47 × 103 g/mol 
B)  5.62 × 101 g/mol 
C)  9.34 × 102 g/mol 
D)  2.81 × 101 g/mol 
E)  1.34 × 102 g/mol

Liquid A has vapor pressure x. Liquid B has vapor pressure y, and x > y. What is the mole fraction of A in the liquid mixture if the vapor above the solution is 30% A?

A solution of two liquids, A and B, shows negative deviation from Raoult's law. This means that

The destruction of a colloid is called

Which of the following will cause the calculated molar mass of a compound determined by the freezing-point depression method to be greater than the true molar mass?

When a 19.4-g sample of an unknown compound is dissolved in 458.0 g of benzene, the freezing point of the resulting solution of 3.82°C. The freezing point of pure benzene is 3.86°C, and K_f for benzene is 5.12°C/m. Calculate the molar mass of the unknown compound.

Atoms, Molecules, and Ions

Stoichiometry

Types of Chemical Reactions and Solution Stoichiometry

Gases

Chemical Equilibrium

Acids and Bases

Applications of Aqueous Equilibria

Energy, Enthalpy, and Thermochemistry

Spontaneity, Entropy, and Free Energy

Electrochemistry

Quantum Mechanics and Atomic Theory

Bonding: General Concepts

Covalent Bonding: Orbitals

Chemical Kinetics

Liquids and Solids

The Representative Elements

Transition Metals and Coordination Chemistry

The Nucleus: a Chemists View

Organic and Biochemical Molecules

Filters

Exam 17: Properties of Solutions

Liquid A has vapor pressure x. Liquid B has vapor pressure y, and x > y. What is the mole fraction of A in the liquid mixture if the vapor above the solution is 30% A?

A solution of two liquids, A and B, shows negative deviation from Raoult's law. This means that

The destruction of a colloid is called

Which of the following will cause the calculated molar mass of a compound determined by the freezing-point depression method to be greater than the true molar mass?

When a 19.4-g sample of an unknown compound is dissolved in 458.0 g of benzene, the freezing point of the resulting solution of 3.82°C. The freezing point of pure benzene is 3.86°C, and Kf for benzene is 5.12°C/m. Calculate the molar mass of the unknown compound.

Atoms, Molecules, and Ions

Stoichiometry

Types of Chemical Reactions and Solution Stoichiometry

Gases

Chemical Equilibrium

Acids and Bases

Applications of Aqueous Equilibria

Energy, Enthalpy, and Thermochemistry

Spontaneity, Entropy, and Free Energy

Electrochemistry

Quantum Mechanics and Atomic Theory

Bonding: General Concepts

Covalent Bonding: Orbitals

Chemical Kinetics

Liquids and Solids

The Representative Elements

Transition Metals and Coordination Chemistry

The Nucleus: a Chemists View

Organic and Biochemical Molecules

Filters

When a 19.4-g sample of an unknown compound is dissolved in 458.0 g of benzene, the freezing point of the resulting solution of 3.82°C. The freezing point of pure benzene is 3.86°C, and K_f for benzene is 5.12°C/m. Calculate the molar mass of the unknown compound.