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# What are (a) Tf and (b) pf?

A gas with initial conditions pi, Vi, and Ti expands isothermally until Vf = 3 Vi.

A) Tf/Ti=

B) pf/pi=

help im lost!!!

### 2 Answers

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- kirchweyLv 71 decade agoFavorite Answer
A. Tf/Ti = 1; that's the definition of isothermal.

B. PV/T = constant. With T constant, PV = constant ==> Pf/Pi = Vi/Vf = 1/3.

- Anonymous1 decade ago
If I read everything correctly and assume the i stands for initial and f stands for final states then : well first since its isothermal that means there is no change in the temperature of the system.

so for a. : Tf/Ti = 1

so B. is quite easy if you assume ideal gas. With an ideal gas equation (P = nRT/V) you end up with PV = constant. so then you have : PiVi = PfVf which becomes PiVi = Pf*3Vi solve for Pf / Pi you get

Pf/Pi = 1/3

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