Misunderstood Thermodynamic question

[Abdlellah]

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.

 

[rude man]

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

What is c_p for an ideal diatomic gas?

 

[Abdlellah]

I have just the general formula of diatomic !

 

[rude man]

I have just the general formula of diatomic !

So graph it already!

 

[Abdlellah]

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

 

[rude man]

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?

 

[Abdlellah]

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

 

[rude man]

that what i get is it right ?

What happened to c_p = 7R/2 where R is the theoretical, constant value of R?

 

[Abdlellah]

What happened to c_p = 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 ?

 

[rude man]

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 c_p 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?

 

[Abdlellah]

Oooooh I got it thank you very much :D I made the straight line because its constant

 

[rude man]

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?

 

[Abdlellah]

I'm using my iPad so I can't upload it. I'll upload it once I get home. Thank you toooooo much