Problem Set #10: Thermodynamic Concepts and Analysis

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

2024
Views:

180

Pages:

2
Author:

Alexis H.

Problem Set #10 Assigned: Jan. 31, 2024 Due: Feb. 2, 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. Consider the following variables from thermodynamics: U, H, p, T, V, q, and w. Which of these are state functions and which are path functions? 2. (a) Explain the difference between the change in internal energy and the change in enthalpy for a given process. (b) Under what circumstances is it more important to consider U and under what circumstances is it more appropriate to consider H? 3. Consider the amount of heat, qv, transferred to a monatomic perfect gas to raise its temperature 1 °C under constant volume conditions. Next, consider the amount of heat, qp, needed to raise the same gas 1 °C under constant pressure conditions against a fixed external pressure of 1 atm. Which one is greater? Explain your answer in 25 words or less. 4. The density of calcite is 2.71 g/cm3, while the density of aragonite is 2.93 g/cm3. Consider the transformation of 1.00 mol of calcite to 1.00 aragonite at 1 bar. This is an endothermic reaction. Which value would you expect to be larger for this process, Hm or Um? Explain your answer in 25 words or less. 1 state functions UH pT V 2 pathfunctions qand W (a) the differences is the change in internal energy is the amount of energy required to create a change in the internal energy of a system whereas the change in enthalpy is the amount of energy required to create a change in the internal energy of the system plus the amount of work done on the surroundings (b) it is more important to consider delta U when the process is isothermic, isobaric, or isochoric, and it is more important to consider delta H when the process is adiabatic 3 heat capacity at constant pressure is greater than heat capacity at constant volume due to the amount of heat required at constant pressure used to increase internal energy and external work 4 the change in internal energy would be greater since it is an endothermic process and the change in enthalpy will likely be negative