Discussion Worksheet - General Chemistry II | CHEM 104, Exams of Chemistry

Download Discussion Worksheet - General Chemistry II | CHEM 104 and more Exams Chemistry in PDF only on Docsity! Chemistry 104 A/D Discussion Section Worksheet Discussion Section #2 Key Ideas from Lecture #2: -1st Law of Thermo: -Systems and surroundings: - ΔE = q + w; or… ΔE = q - PextΔV Let’s think about these concepts for a bit... We create a helium balloon in Champaign-Urbana and then “let it go.” We watch as the balloon rises into the air. What will happen to the internal energy of the He atoms as the balloon floats away? Will the balloon keep rising forever? Why/Why not? What would happen to the internal energy of the He atoms as the balloon floats towards the tropics? Problems: Hour Exam I, Fall 2007, #7 As a system increases in volume, it absorbs 48.3 J of energy in the form of heat from the surroundings. The piston is working against a pressure of 0.450 atm. The final volume of the system is 58.0 L. What was the initial volume of the system if the internal energy of the system decreased by 98.5 J? Stuck? List all the information that you know. Start with Sample Exercise 6.1 (pg 233 of Zumdahl) then apply your answer to Sample Exercise 6.2 (pg 234 of Zumdahl). Make sure to pay attention to your units! The following problems from Suggested Problems #1 also deal with these concepts: Zumdahl: 6.21, 6.25, 6.27, 6.29, 6.30, and 6.83. Hour Exam I, Spring 2007, #6 The combustion of air and gasoline vapor inside a piston is one of the more practical applications we can look at in this classroom right now (how many of you have used a car/public transportation in the last couple of days…be thankful for this reaction!). Consider a piston that has an initial volume of 0.040 L. During the combustion of the air/gas mixture 950 J of energy is released. If all of this energy is converted to work, what will the final volume of the piston be if expanding against a constant pressure of 0.86 atm? Stuck? List all the information that you know. Start with Sample Exercise 6.1 (pg 233 of Zumdahl) then apply your answer to Sample Exercise 6.2 (pg 234 of Zumdahl). Make sure to pay attention to your units! 1