Consider a stoppered flask containing benzene, iodine, and air

[fallenrose]

1. Consider a stoppered flask containing benzene, iodine, and air, which has reached equilibrium at 298K. Which one of the following statements converning the system at equilibrium is true?
a) The pressure of the vapour phase is not constant
b) Evaporation of the liquid continues.
c) The colour of the liquids phase will change
d) The mass of the solid iodine is not constant.

2. Consider the equilibrium represented by the following equation:
Heat + H2O(l) <----
-----> H2)(g) in which T = 373K, P= 101kPa
a) The total volume of the system is increased.
b) Boiling water is added to the system
c) Water vapour is removed from the system.
d) The system is cooled.

3. Consider the following systems:
a) a container that is half-filled with alchol, soppered, and allowed to stand for several days
b) crystals of KMnO4 that are dissolved in water until the water becomes a uniform purple colour and a constant amount of crystal remains in the container.
c) an ice cube in a beaker of water in a normal classroom
d) moth balls that are placed in an empty flask that is then stoppered and allowed to stand for several days
Which of the above are in an equilibrium state?
i) a and b only
ii) a, b, and d only
iii) b and c only
iv) a, b, c and d

Ok for the fist answer

1. it think its b because when the system reaches equailibrium evaporation of the liquid will happen at the same rate that condensation happens.

2. I am sort of lost on this one but i think it mite be b because wen you add the boiling water the temperature will go up and so will the kenitic energy. :S please tell me if I am on the rite track wit this one.

3. this one i think would be a,b and d because in c the water would evaporate and because of that it would not be in equailibrium.

 

[chemisttree]

You sound like you have a good handle on the questions, but '2' isn't complete. What question is being asked here?

 

[fallenrose]

oh sori about that i didnt type a part of the question.

2. Consider the equilibrium represented by the following equation:
Heat + H2O(l) <----
-----> H2)(g) in which T = 373K, P= 101kPa

Which of the following will favour the reverse reaction?

a) The total volume of the system is increased.
b) Boiling water is added to the system
c) Water vapour is removed from the system.
d) The system is cooled.

so are the other answers correct..does the logic make sense?

 

[chemisttree]

You need to think more carefully about '2'.

 

[fallenrose]

is it a because i think increase the volume of a system does change it and so does temperature..can someone help me out with this one..

 

[chemisttree]

Consider the choices one at a time. 'a' asks what would happen if the volume were increased. What happens to the pressure and the temperature when this occurs? 'b' asks what would happen when boiling water were added to the system. It would probably help to understand that the temperature of boiling water is 373 K, the same temperature as the equilibrium temperature. 'c' asks what would happen if the product (water vapor) were removed from the system. Would this affect the equilibrium? You should probably write an expression for the equilibrium and see for yourself... or consult LeChatelier. 'd' asks what would happen if the system were cooled... effectively removing one of the reactants (heat). What happens to the equilibrium expression when heat is removed?