Reference Chang 530 4 A sample of nitrogen gas kept in a container of volume 23

# Reference chang 530 4 a sample of nitrogen gas kept

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(Reference: Chang 5.30) 4. A sample of nitrogen gas kept in a container of volume 2.3 L and at a temperature of 32°C exerts a pressure 4.7 atm. Calculate the number of moles of gas present. (8 points) V=2.3L T=32°C= (32+273)K= 305K P=4.7atm R=.0821Latm/K mol n = PV RT 4.7 ( 2.3 ) .0821 ( 305 ) 10.81 25.0405 →n = .43 mol (Reference: Chang 5.31) 5. What volume will 5.6 moles of sulfur hexafluoride (SF 6 ) gas occupy if the temperature and pressure of the gas are 128°C and 9.4 atm? (8 points) n=5.6mol T=128°C=(128+273)= 401K P=9.4atm R= .0821L V = nRT P 5.6 ( .0821 ) ( 401 ) 9.4 184.36 9.4 19.6123 →V = 20 L (Reference: Chang 5.33) 6. A gas-filled balloon having a volume of 2.50 L at 1.2 atm and 25°C is allowed to rise to the stratosphere (about 30 km above the surface of Earth), where the temperature and pressure are –23°C and 3.00 × 10 –3 atm, respectively. Calculate the final volume of the balloon. (8 points) P 1 V 1 T 1 = P 2 V 2 T 2 1.2 ( 2.5 ) 298.15 3.00 10 3 ( V 2 ) 250.15 3 298.15 = 3.00 10 3 ( V 2 ) 250.15 .0101 = 3.00 10 3 ( V 2 ) 250.15 2.527 = 3.00 10 3 ( V 2 ) 839 L (Reference: Chang 5.35) 7. A 2.10-L vessel contains 4.65 g of a gas at 1.00 atm and 27.0°C. (a) Calculate the density of the gas in grams per liter. (b) What is the molar mass of the gas? (10 points) A)V=2.1L Mass=4.65g D = m v 4.65 2.10 = 2.214 g / L B) V=2.1L P= 1atm m=4.65g T=27.0°C= (27+273)= 300K 2 Copyright © 2017 by Thomas Edison State University . All rights reserved.
4.65 g ( .0821 L )( 300 K ) 1 atm ( 2.10 L ) 114.5295 2.10

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