The discussion revolves around calculating the amount of heat supplied to a multatomic gas during a temperature increase of 100K under conditions described as free expansion. The original poster expresses uncertainty about how to approach the problem and mentions a specific answer of 3320kJ.
Participants are actively engaging with the problem, exploring various interpretations of the conditions and attempting to derive necessary values. Some guidance has been offered regarding the relationship between heat capacity and the specific gas type, but no consensus has been reached on the correct approach or definitions.
The original poster has limited information, only providing the temperature change and the amount of gas. There is uncertainty about the specific heat capacity for the multatomic gas and how it relates to the problem at hand.
I do not have any definition. It is said in the task. I guess it means, there is nothing influencing the expansion of gas.Chestermiller said:What is your definition of free expansion conditions?
Usually, free expansion is defined as expansion into a vacuum. However, I don't think that is what was intended here. I think what was intended here is expansion against a constant pressure equal to the initial pressure of the gas. If that were the case, then the amount of heat supplied would be equal to the change in enthalpy of the gas. This is given by $$Q=\Delta H=nC_p\Delta T$$where n is the number of moles and ##C_p## is the molar heat capacity of the gas. Are you given no information about the gas? If not, from the answer they gave, what is the molar heat capacity of the gas?MisterP said:I do not have any definition. It is said in the task. I guess it means, there is nothing influencing the expansion of gas.
There is nothing more.. Just the temperature - 100K (how much it was risen) and 1kmole, that`s it.. Maybe the fact that it is multi-atom gas changes something?Chestermiller said:If not, from the answer they gave, what is the molar heat capacity of the gas?
Not really. What do you calculate for Cp? That might tell us something.MisterP said:There is nothing more.. Just the temperature - 100K (how much it was risen) and 1kmole, that`s it.. Maybe the fact that it is multi-atom gas changes something?
Let's see the number you get using their answer.MisterP said:I really do not know.. :(
Edit: or c = Q / (mΔT). ??
But that won`t help..
Dues the equation I wrote make sense to you? What course is this for?MisterP said:I do not get it. I have not been solving these types of tasks since I was in high school, that's around 13 years ago and now they through all the themes on basic physics and I have to solve this "easily" they say ..
We are trying to "back out" the value of Cp from the answer they gave to see if we can make any sense out of it.MisterP said:We had 3 day course on physics - starting mechanics, energy, oscilations, molecular physics, thermodynamics, electrics. I am studying electric engeneering and so, there is this fast course on physics, just for a check. I do understand Your formula, but I do not have Cp.
Very nice.MisterP said:So, I found this. E = x*n*R*T
If x = 4, then I get right answer, but I do not know if this is right. But I have seen that x is 3.
n - moles
R - 8.3 constant
T - temperature
Edit: x = i/2+1
i = 6 for multi atomic gases, so that is how to get 4 and seems like this formula works :)