University:
The Pennsylvania State University
Course:
CHEM 450 | Thermodynamics
Academic year:

2024
Views:

365

Pages:

2
Author:

Alexis H.

Problem Set #8 Assigned: Jan. 26, 2024 Due: Jan. 29, 2024 at 2:30 pm Upload your answers to the Canvas website. PDF files are preferred, but Microsoft Word, or image files will be accepted. Please check to make sure that your submission is legible. 1. What is the difference between “reversible” and “irreversible” expansion? 2. A chemical reaction takes place inside a cylindrical container fitted with a piston that has a cross-sectional area of 50 cm2. Because of this reaction, the piston is pushed out 15 cm against an external pressure of 1 atm. Calculate the work that this done. (Hint: Be careful to consider the sign! We are always considering the system in thermodynamics.) 3. A sample consisting of 1.00 mol Ar is expanded isothermally at 20 °C from 10.0 L to 30.0 L. Find the values of q, w, and U, if the process is performed (a) reversibly, (b) against a constant external pressure equal to the internal pressure of the gas after expansion to 30 L, and (c) against an external pressure of 0.0 atm. 1. in reversible expansion the external pressure and the internal pressure are equal throughout the process while in an irreversible expansion there is a di erence in the external and integral pressure throughout the expansion. 2 0.005m A P 1.0 Work Force 101,325Pa Distance F pA p Work pA D work 101,325 work 3 101,325Pa a 0.15m 75.99 J w force W 0.005 distance pA D b W P Vf V I p p In W NRT W 1.00 8.314 293.15 In 3 W 3086.7J ΔU C 9 0 work is zero because nowork can be done against zero externalpressure 0 9 WO P W IT 1.00 8.314 293.15 10 0.001 242 16 KPa 242.16 30 10 0.001 4.8432k Δ0 g 0 w