How Does Heating Affect the Properties of Nitrogen Gas?

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Homework Help Overview

The discussion revolves around the heating of nitrogen gas (N2) at constant volume, focusing on the effects of temperature changes on various properties such as pressure, internal energy, work done, heat flow, and entropy. Participants are exploring the implications of the ideal gas assumption in this context.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are discussing relevant equations that relate pressure, temperature, and volume for gases. There is a focus on whether nitrogen can be treated as an ideal gas, with questions about how to determine the validity of this assumption. Some are considering the compressibility factor and its proximity to 1 as a criterion for ideal behavior.

Discussion Status

The discussion is active, with participants sharing insights on how to approach the problem. Some guidance has been offered regarding the assumption of ideal gas behavior, and there is a recognition of the need to verify this assumption through calculations. Multiple interpretations of the problem are being explored, particularly concerning the ideal gas law.

Contextual Notes

Participants are navigating the constraints of the problem, including the lack of explicit information about the gas's behavior and the implications of treating it as an ideal gas. There is also mention of the problem being similar to past exam questions, which adds a layer of urgency to the discussion.

C.E
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1. 0.005 kg of nitrogen gas (N_2 – molecular weight 0.028 kg mol-1) are heated at
constant volume (V = 3.5 x 10^-3 m^3) resulting in a pressure increase from an initial
value pi = 1.2 x 10^5 Pa to a final value pf = 1.8 x 10^5 Pa. Answer the following
questions:

(a).What are the initial and final temperatures of the gas?

(b). What is the change in the internal energy of the gas?

(c). What is the work done by the gas?

(d). What is the heat flow into or out of the gas during the process?

(e). What is the change in entropy of the gas?

Hi, I am having trouble getting started on the above question could somebody please help me?
 
Last edited:
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Do you know any equations relating pressure, temperature, and volume for a gas?
 
I seem to always have the same problem with this type of question. I know formulas for ideal gasses and think I could answer the question for an ideal gas but I am not told that the gas is ideal in the question. How do I know when I can assume it is ideal?
 
Check if the http://en.wikipedia.org/wiki/Compressibility_factor" is sufficiently close to 1.
 
Last edited by a moderator:
When it says molar volume do you just find that by dividing the volume by the number of moles?
 
C.E said:
When it says molar volume do you just find that by dividing the volume by the number of moles?

Yes.
 
How close to 1 should I take to be sufficiently close? (I really prefer them questions which say assume it behaves like an ideal gas).
 
What did it end up being?
 
I couldn' t do it as I do not know the temperature of the gas. (Though thanks for the suggestion it will no doubt be useful in
other questions).

Should I just assume the gas is ideal anyway?
 
Last edited:
  • #10
The standard approach is to assume ideality, make the calculations, and then check the assumption.
 
  • #11
So if something similar to this comes up in my exam (this was a past exam question) would you recommend I just assume the gas is ideal?
 
  • #12
Yes.
 

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