[omiexstrike]

Hi everyone, I need some help on a Calorimetry question. I have an exam coming up soon and I don't understand this. If you can show your steps and explain where it says to explain, that will be much appreciated it. Thank you!

1) (a) A sample of gas occupies a volume of 1.50 L when its pressure is 2.00 atmospheres. If the gas is allowed to expand, isothermally, against a constant external pressure of 1.00 atmospheres, what will be the amount of (i) mechanical work energy and (ii) the amount of heat energy that will have to be exchanged between the gas and its surroundings? What will be the value of Delta E for this process? Briefly explain how you arrive at your answers.

(b) If the same amount of gas, as in part (a), is placed into a 1.50 L container which is connected to another 1.50 L container by the means of a valve, which is closed. The second container is evacuated and the whole apparatus is enclosed by perfect thermal insulation. The valve is now opened and the gas expands to fill both containers. (i) What will be the amount of mechanical work that is done in this expansion? (ii) What amount of heat will be exchanged in this process? What is the value of Delta E for this process? Briefly explain how you arrive at your answers.

(c) Compare your calculated results for parts (a) and (b). What is the significance of what you have found?

Sorry it seems like a lot. I just don't understand it and would appreciate some help. Thanks so much again. =) 

[Borek]

You have to show your attempts at solving the question to receive help. This is a forum policy.

At least list relevant equations.

[omiexstrike]

Well, the problem is I don't really know how to start it. I'm not understanding the problem in the first place. Anyways, here are some things that I know:

(a) So far, I know that internal energy (U or E)= q(heat) + w(work). w= - pressure*volume change at constant pressure. Since it is isothermal, change in internal energy is 0 so 0=q+w and therefore, q=-w. I also know that if I want to express the answer in Joules, I need to multiply by a conversion factor of 101.325 J/(L*atm).

(b) I believe that the key phrase in this problem is "second container is evacuated." I believe this means that the second container is a vacuum therefore there is no pressure. Also, it receives no heat from the surroundings and that expansion into a vacuum is called "free expansion" and no work is done since the pressure pushing against it is 0. If the gas expands isothermally (E=0) like in the first problem then I think I can use algebra to determine heat change so E=q+w, 0=q+0, and q=0.

My main problem with both of these is that I don't know how to start it and what to plug in where, etc. Above is what I know so far and there were no equations given with this problem by the way.

Thanks.