Mastering Physics 5

# Mastering Physics 5 - Course PHYSICS260 Assignment 5...

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Course PHYSICS260 Assignment 5 Consider ten grams of nitrogen gas at an initial pressure of 6.0 atm and at room temperature. It undergoes an isobaric expansion resulting in a quadrupling of its volume. (i) After this expansion, what is the gas volume? (ii) Determine the gas temperature after this step. In the next process, the gas pressure is decreased at constant volume until the original temperature is reached. (iii) After this decrease in gas pressure, what is the value of the pressure? In the final process, the gas is retured to its initial volume by isothermally compressing it. (iv) Determine the final gas pressure. (v) Using appropriate scales on both axes, show the full three-step process on a p V diagram. Introduction to the Ideal Gas Law Description: Practice using the ideal gas law with a series of questions in which all but two gas parameters are held fixed. Learning Goal: To understand the ideal gas law and be able to apply it to a wide variety of situations.

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The absolute temperature , volume , and pressure of a gas sample are related by the ideal gas law , which states that . Here is the number of moles in the gas sample and is a gas constant that applies to all gases. This empirical law describes gases well only if they are sufficiently dilute and at a sufficiently high temperature that they are not on the verge of condensing. In applying the ideal gas law, must be the absolute pressure, measured with respect to vacuum and not with respect to atmospheric pressure, and must be the absolute temperature, measured in kelvins (that is, with respect to absolute zero). If is in pascals and is in cubic meters, use . If is in atmospheres and is in liters, use instead. Part A A gas sample enclosed in a rigid metal container at room temperature (20 ) has an absolute pressure . The container is immersed in hot water until it warms to 40 . What is the new absolute pressure ? Part A.1 How to approach the problem To find the final pressure, you must first determine which quantities in the ideal gas law remain constant in the given situation. Note that is always a constant. Determine which of the other four quantities are constant for the process described in this part. Check all that apply. ANSWER: Now manipulate the ideal gas law ( ) so that , , and , the constants in this situation, are isolated on the right side of the equation: . Since the right side of the equation is a constant in this situation, the quantity , which is always equal to , must be the same at the beginning and the end of
the process. Therefore, set . Plug in the values given in this part and then solve for , the final pressure. Part A.2 Convert temperatures to kelvins To apply the ideal gas law, all temperatures must be in absolute units (i.e., in kelvins). What is the initial temperature in kelvins? ANSWER:

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## This homework help was uploaded on 04/09/2008 for the course PHYS 260 taught by Professor Chen during the Spring '08 term at Maryland.

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Mastering Physics 5 - Course PHYSICS260 Assignment 5...

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