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

AI Thread Summary
The discussion revolves around calculating the change in temperature of a monatomic ideal gas in a sealed container. The initial conditions include a pressure of 1.01 x 10^5 Pa and a volume of 0.0224 m3, with a final volume of 0.0155 m3 and a final pressure of 1.35 x 10^5 Pa. The initial temperature was correctly calculated as 136 K, but the final temperature was incorrectly derived as 128.7 K, leading to a change in temperature (Delta T) of -7.3 K, which is disputed. The user suggests that the error may lie in the calculation of the final temperature and proposes using the ideal gas law to solve for Tf. The discussion emphasizes the need to verify calculations to ensure accuracy in thermodynamic assessments.
mattmannmf
Messages
170
Reaction score
0
Not sure what I am 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...
 
Physics news on Phys.org
It must be the final temp that I am doing wrong
 
Try,

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

solve for Tf
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top