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Unformatted text preview: Midterm I Version B Information you may (or may not) find useful Constants constant value unit Plancks constant ( h ) 6 . 626 10 34 J s Rydberg constant ( R H ) 2 . 178 10 18 J speed of light 2.997924 10 8 m/s Avogadros number 6 . 022 10 23 gas constant (R) 8 . 31451 J/K mol gas constant (R) . 08206 L atm/K mol electron charge ( e ) 1 . 6022 10 19 C electron mass 9 . 1094 10 31 kg Proton mass 1 . 67252 10 27 kg Neutron mass 1 . 67495 10 27 kg 1 1 ldeal Gas Law Consider an expandable balloon filled with 6.20 g of CH 4 gas. The pressure of the gas is the same as the outside pressure (1.00 atm) and the volume is 10.0 L. a What is the temperature of the gas? n = 6 . 20 g 16 . 04 g/mol = 0 . 387 mol of CH 4 T = pV nR = 1 . 00 10 . . 387 . 08206 = 315 K Answer: 315 K 6 points b The weather changes. The pressure rises to 1.10 atm and the balloon expands to 11.2 L. Calculate the new temperature of the gas. T 2 = T 1 p 2 V 2 p 1 V 1 = 315 1 . 10 11 . 2 1 . 00 10 . = 388 K Answer: 388 K 6 points c Consider another expandable balloon with a volume of 8.00 L at 1.00 atm and 15.0 o C. Given that the total mass of the gas is 10.26 g, calculate the molar mass of the gas. d = m/V = 10 . 26 g/ 8 . 00 L = 1 . 283 g/L M = dRT p = 1 . 283 . 08206 288 . 15 1 . 00 = 30 . 34 g/mol Answer: 30.3 g/mol 8 points 2 2 Partial Pressure A 10.0 L cylinder at 1.00 atm and 21.0 o C contains F 2 gas. a Calculate the number of moles of the gas in the cylinder. n = pV RT = 1 . 00 10 . . 08206 (21 . 0+273 . 15) = 0 . 414 mol of F 2 Answer: 0.414 mol 6 points b The cylinder is connected to a second cylinder with a valve. The second cylinder has a vol ume of 5.00 L and contains 0.800 mol of SO 2 gas. After opening the valve, the gases mix and the temperature decreases to 18.5the temperature decreases to 18....
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This note was uploaded on 02/27/2012 for the course CHEM 1B 600031 taught by Professor Potma during the Spring '12 term at UC Irvine.
 Spring '12
 POTMA

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