Question

A chemistry question

Answer 1

The apparatus shown consists of three temperature-jacketed 1.000L bulbs connected by stopwingspans. Bulb A contains a mixture of H2O (g), CO2 (g) and N2 (g) at 25 °C and a total pressure of 564 mmHg. Bulb B is empty and is held at a temperature of -70 °C. Bulb C is also empty and is held at a temperature of -190°C. The stopwingspans are closed and the volume of the lines connecting the bulbs is zero. CO2 sublimes at -78°C and N2 boils at -196°C.

A) The stopwingspan between A and B is opened, and the system is allowed to come to equilibrium. The pressure in A and B is now 219 mmHg. What do bulbs A and B contain?

B) How many moles of H2O are in the system?

C) Both stopwingspans are opened and the system is again allowed to come to an equilibrium. The pressure throughout the systems is 33.5 mmHg. What do bulbs A, B and C contain.

D) How many moles of N2 and CO2 are in the system?

Answer 2

I would really appreciate if someone explained to me how they knew what chemicals are in what bulbs and why, @aaronq

Answer 3

* word is not stopwingspan, it is stopwingspans.

Answer 4

stopc-o-c-k-s i know, the site thinks otherwise.

Answer 5

They probably put the gases in themselves, regular lightbulbs are filled with an inert gas.

Answer 6

Hey, I tried to reason this by saying that the effusion rate of H20 is greater than N2 and CO2 and so on but Im not sure.

Answer 7

They are just colour coded that's all. All the gases are in the bulb A and when the stopc-oc-k is removed the gases move and effuse.

Answer 8

@aaronq Im trying to understand this because if they ask this in an actual evaluation than I need to know what to explain to the TA's

Answer 9

you don't have to take into account the effusion of the gases, it's time-indepenent, they let it come to an equilibrium.

When you open the valves, you'll just have a larger container, the temperature will equilibrate, and the gases themselves will cool down decreasing the pressure.

Answer 10

I know that H2O will probably freeze if it goes anywhere, but what about the other gases?

Answer 11

@aaronq how can I predict the behavior of the other gasses throughout all the steps?

Answer 12

the told you the sublimation (solid to gas) point for CO2 and for N2

Answer 13

ok I guess than that N2 goes into the second bulb and first bulb as well as CO2. So H2O will be frozen either way. so I calculate n for bulb a and B and subtract it from the n initial from the beginning? n initial - na -nb? @aaronq