Getting strange answer , lease help

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The discussion revolves around calculating the mass of air in a given volume under specific conditions using the ideal gas law. The initial parameters include a volume of 2.2 m³, a pressure of 1.2 bar, and a temperature of 303 K. The user initially misapplied the universal gas constant, mistakenly using 6 instead of the correct value of 0.287 kJ/kg K. After correcting the calculation, the user arrives at a mass of approximately 29.90 grams of air. The conversation highlights the importance of using the correct gas constant in thermodynamic calculations.
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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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R is the universal gas constant. It is not 6.
 
FredGarvin said:
R is the universal gas constant. It is not 6.
OMG, I just spit water all over my keyboard. :smile:
 
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
 
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