Getting strange answer , lease help

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In summary, the conversation discusses a process involving a volume of 2.2m^3 of air at initial conditions of 1.2bar and 303K. The process includes isothermal compression, isobaric expansion, and isochoric cooling. The question is to find the mass of air present, which is calculated using the formula PV=nRT. The correct calculation for the mass of air present is given as 29.90g.
  • #1
xto
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The question is
a volume of 2.2m^3 of air at inital conditions of 1.2bar and 303K undergoes the following process to complete a cycle :

i)isothermal compresssion from state 1 through a volumetric compression ration of 6 to state 2

ii) isobaric expansion from state 2 back to the initial volume thus reaching state 3

iii) isochoric cooling from state 3 back to the original pressure to reach state 1

Q1) Find the mass of air present

so i use the formula PV=nRT

P=1.2bar
V=2.2M^3
n=?
R=6
T=303K

so i need to find N so i got 2.64 = 1818N
which N is 1.452x10^-3 :cry:
which is total not the mass of the air , please help
 
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  • #2
R is the universal gas constant. It is not 6.
 
  • #3
FredGarvin said:
R is the universal gas constant. It is not 6.
OMG, I just spit water all over my keyboard. :rofl:
 
  • #4
ok , i kind of get it
beacuse I'm given 2 R
Rv is 6
the other R is 0.287kJ/kg K

so its

(1.1832)x(2.2x10^3)
---------------------
(0.287)x(303k)

then i get 29.90g (to 2d.p) Air

is that right for the mass of air present? By the way , thank you so much for the help
 

1. Why am I getting strange answers?

There could be several reasons for this. It could be due to incorrect input data or an error in the calculations. It could also be due to limitations in the model or assumptions made.

2. How do I troubleshoot strange answers?

Start by double-checking your input data and equations. Make sure all units are consistent and there are no typos. If the problem persists, try simplifying the problem and breaking it down into smaller parts to identify the source of the issue.

3. Can strange answers be caused by experimental error?

Yes, experimental error can contribute to strange answers. It is important to carefully plan and conduct experiments to minimize error and ensure accurate results. Additionally, repeating experiments and taking multiple measurements can help identify and reduce experimental error.

4. How can I improve the accuracy of my answers?

To improve accuracy, it is important to use reliable and precise measurement tools, carefully record data, and critically analyze and interpret results. It may also be helpful to consult with colleagues or experts in the field for feedback and suggestions.

5. What should I do if I still can't get the right answer?

If you are still struggling to get the right answer, don't hesitate to seek help from others. Collaborating with colleagues or consulting with experts can provide new perspectives and insights that may help you find a solution. Additionally, trying different approaches or seeking additional resources such as textbooks or online tutorials can also be beneficial.

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