Misunderstood Thermodynamic question

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Homework Help Overview

The discussion revolves around plotting the specific heat capacity (cp) of oxygen (O2) as a function of temperature and comparing it to the expected cp for a diatomic ideal gas. Participants are attempting to understand how to represent these values graphically and the implications of using a constant value for cp.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the need to plot cp for O2 against the theoretical cp for a diatomic ideal gas, which is described as a constant value. There are questions about the correct value of R to use and how to graphically represent the data. Some participants express confusion about the requirements of the problem and the calculations involved.

Discussion Status

There is ongoing exploration of how to accurately plot the data and what values to use. Some participants have provided guidance on the theoretical aspects of cp and R, while others are still clarifying their understanding of the graphing process. The discussion reflects a mix of attempts and questions without a clear consensus on the final approach.

Contextual Notes

Participants are working under the constraints of homework rules, which may limit the information they can share or the methods they can use. There is also a mention of varying values of cp for O2 and the importance of unit compatibility in the graph.

Abdlellah
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Homework Statement


Plot cp as a function of temperature for O2? How does this compare with the cp expected for a diatomic ideal
gas. Add this constant value to your plot. At what temperatures does the real value of cp approach that
expected for a diatomic ideal gas.


Homework Equations



I plot the Cp as a function of temperature for O2?

the second part totally i misunderstand it i don't know what i should do

The Attempt at a Solution



this is what i did ( see that attachment please)

if u want to see the tables (click here )

table number 2.
 

Attachments

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Looks to me like you plotted cp for oxygen vs. hydrogen. You were asked to plot cp for oxygen vs. cp for an ideal diatomic gas, which the problem states is a constant.

What is cp for an ideal diatomic gas?
 
I have just the general formula of diatomic !
 
Abdlellah said:
I have just the general formula of diatomic !

So graph it already!
 
Sorry I'm really bad in this :(
This is the general formula
cp = 7/2 R

What is the values of R that I have to put it.
Im thinking to calculate the Cp by taking the R value of O2 from table. But I will get only one point how I would graph it
 
Abdlellah said:
Sorry I'm really bad in this :(
This is the general formula
cp = 7/2 R

What is the values of R that I have to put it.
Im thinking to calculate the Cp by taking the R value of O2 from table. But I will get only one point how I would graph it

If I give you y = y(x) and say y = cosntant, you know how to graph it, don't you?
 
the value of R at 300 is 0.2 something
so i calculate it and plot it to the graph and that what i got
 
Last edited:
Abdlellah said:
that what i get is it right ?

What happened to cp = 7R/2 where R is the theoretical, constant value of R?
 
rude man said:
What happened to cp = 7R/2 where R is the theoretical, constant value of R?

i changed my answer. the R is constant at 300 K so i put the point at 300 K
is it now correct ?
 

Attachments

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  • #10
Abdlellah said:
i changed my answer. the R is constant at 300 K so i put the point at 300 K
is it now correct ?

The theoretical R is the same for all gases and is temperature-independent. But be aware that your units of R must be compatible with the units of your chart (the varying values of cp for O2.

Also, when you do get the right value for R, since it's temperature-independent, what is the correct way to graph it on your graph?
 
  • #11
Oooooh I got it thank you very much :D I made the straight line because its constant
 
  • #12
Abdlellah said:
Oooooh I got it thank you very much :D I made the straight line because its constant

Ats'a way to go!
What's your total graph look like anyway?
 
  • #13
I'm using my iPad so I can't upload it. I'll upload it once I get home. Thank you toooooo much
 

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