Change in temperature between the initial and final state of the gas?

mattmannmf

Not sure what im doing wrong

What is the change in temperature between the initial and final state of the gas?

A) A monatomic, ideal gas is in a sealed container (the number of gas molecules is always constant: n = 2 moles); the initial pressure is Pi = 1.01 x 10^5 Pa and the initial volume is Vi = 0.0224 m3.

First, the volume of the gas is decreased at a constant pressure (at Pi = 1.01 x 10^5 Pa) to a final volume of Vf = 0.0155 m3.
Second, the pressure of the gas is increased at a constant volume (at Vf = 0.0155 m3) to a final pressure of Pf = 1.35 x 10^5 Pa.

R=8.13 (given)

Initial Temp= (1.01x10^5*.0224)/(8.13*2)= 136 (this is correct)
Final temp= (1.35x10^5*.0155)/(8.13*2)= 128.7

Delta T= Tf-Ti....128.7-136= -7.3 (which isn't correct)

what am i doing wrong...

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mattmannmf

It must be the final temp that im doing wrong

iamthegelo

Try,

(Pi*Vi)/Ti = (Pf*Vf)/Tf

solve for Tf

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