Vapor Pressure in a Binary System
Colligative Properties Application
Colligative Properties Calculation
Setting up Equilibrium Expressions
Determining Rxn Direction
100
The vapor pressure of substance A is 6 atm and the vapor pressure of substance B is 4 atm at 40ºC. What is the total vapor pressure if 2 moles of A were mixed with 2 moles of B?
A. 4 atm
B. 5 atm
C. 6 atm
D. 10 atm
B. 5 atm
100
Why do we salt the roads to thaw ice?
A. The osmotic pressure difference between the ice and atmosphere allow for heat to enter the system and melt the ice
B. The salt interferes with the hydrogen bond interactions between H2O molecules, thus lowering the freezing point (freezing point depression) and melting the ice
C. The salt decreases the boiling point of the ice on the roads, allowing for the ice to melt at lower temperatures
D. Adding salt applies pressure to the ice, causing the H2O molecules to come closer together, turning the ice into water
B. The salt interferes with the hydrogen bond interactions between H2O molecules, thus lowering the freezing point (freezing point depression) and melting the ice
100
What is the new freezing point when 190g of MgCl2 is added to 2kg of water, given that the Kf of water is 2? Answer in degrees of Celsius.
The molecular weight of MgCl2 is approximately 95g per mole.
-6oC
100
What is Kc for the chemical reaction below?
CH4(g) + 2O2(g) --> CO2(g) + 2H2O(g)
K = [CO2][H2O]2 / [CH4][O2]2
100
Given that the reaction below has a Kp = 10 and initial conditions are H2 = 0.5 atm, I2 = 1 atm, and HI = 2 atm, which direction does the reaction shift to reach equilibrium?
Q = 8, therefore reaction shifts to the right to reach equilibrium.
200
In a binary system, there is 2 parts substance A and 4 parts substance B. The vapor pressure of substance A is 60 torr and the vapor pressure of substance B is 300 torr at 60ºC. What is the total vapor pressure of the binary system?
A. 60 torr
B. 105 torr
C. 220 torr
D. 300 torr
C. 220 torr
200
Which of the following statements is true about using ethylene glycol in cars?
I. It decreases the 0-100ºC range of pure water
II. It increases the 0-100ºC range of pure water
III. It acts as an antifreeze that prevents water in the radiator from freezing, boiling, and evaporating
IV. It only elevates the boiling point of the water in the radiator
A. I only
B. II only
C. II and III
D. II, III, and IV
C. II and III
200
Assuming standard conditions and given that Kf and Kb are 2 and 0.5, respectively, what is the new boiling point for a solution with dextrose that freezes at 261K? Answer in Kelvin.
*Dextrose is a sugar
376K
200
What is the Kc for the chemical reaction below?
K = [CO2]
200
The reaction below has a Kc = 103. The initial conditions are [A] = 0.1 M, [B] = 0.1 M, and [C] = 1 M. In which direction does the rxn occur?
2A + B --> C
Q = 103. The reaction is at equilibrium.
