### Gas Law Problems - Dalton's Law Answers

The vapor pressure of water in kilopascals is here. Remember to convert to mmHg or atm. as needed.

65. 9.00 atm.

66. PHe = 0.300 x 4.00 atm = 1.20 atm. PAr = 4.00 - 1.20

67. 760.0 mmHg minus 55.3 mmHg

68. 96.00 kPa minus 12.33 kPa

69.

a) 480.0 g O2 / 32.0 g/mol
b) 80.00 g He / 4.00 g/mol
c) 35.0 moles
d) 15.0 mol O2 / 35.0 mol
e) 20.0 mol He / 35.0 mol
f) 7.00 atm x 0.4286
g) 7.00 atm x 0.5714

Keep in mind that once one partial pressure is calculated, the other can be arrived at by subtraction, if so desired.

70. Complete the following table

 O2 Ne H2S Ar Total Moles 5.00 3.00 6.00 9.00 18.00 Mole fraction 5/18 = 0.278 3/18 = 0.167 6/18 = 0.333 4/18 = 0.222 1 Pressure fraction 0.278 0.167 0.333 0.222 1 Partial Pressure 1620 x 0.278= 450.36 1620 x 0.167= 270.54 1620 x 0.0.333= 539.46 1620 x 0.222= 359.64 1620.0

71. (14.0 g / 2.00 g/mol) + (84.0 g /28.0 g/mol) + (2.0 moles) = 12.0 moles total

2.0 / 12.0 = 0.167 of the total pressure. 78.00 is to 0.167 as the total pressure is to one, so 468 mmHg is the answer.

72. The solution is left to the reader.