172
Gases
61 Two or three millihters of a liquid that boils at about 60°C are put into an
Erlenmeyer flask The flask is closed with a polystyrene stopper that has a fine
glass capillary running through it The gas-containing part of the flask is then
completely immersed in a bath of boiling water, which (at the elevation of the
experiment) boils at 98 8°C After a short time the air has been completely
swept out through the capillary, and the excess liquid has boiled away, leaving the flask filled only with the vapor of the liquid At this point the flask is
removed from the boiling water and cooled The vapor condenses to liquid
and air rushes in to fill the flask again The flask, when dry and empty had
weighed 39 5762 g, after the experiment it weighs 40 3183 g The barometric
pressure during the experiment is 730 torr The volume of the flask is determined by filling the flask with water, inserting the stopper to its previous
position, and squeezing out the excess water through the capillary The vol
ume of water so held is 239 6 ml What is the mole weight of the liquid'
62 The liquid used in Problem 61 is analyzed and found to be 24 2% C, 4 05% H,
and 71 7% Cl What is the true molecular formula of this liquid
1
63 An automobile tire has a gauge pressure of 35 0 lb/m
j when the atmospheric
pressure is 14 7 lb/m
2 and the temperature is 40°F What will be its gauge
pressure if its temperature rises to 120°F
9
64 Hydrogen chloride effuses through a hole (under prescribed conditions of
temperature and pressure) at the rate of 2 70 ml/mm At what velocity will
helium effuse through the same hole under the same conditions'
65 It takes 45 sec for a given volume of CO to effuse through a pinhole under
given conditions of temperature and pressure How long will it take for the
same volume of Br 2 vapor to effuse through the same hole under the same
conditions
9
66 Under certain prescribed conditions, O 2 effuses through a pinhole at the rate
of 3 65 ml/mm A mixture of CO and CO 2 effuses through the same pinhole
under the same conditions at the rate of 3 21 ml/mm Calculate the percentage
of CO in the gas mixture
67 A rubber balloon weighing 10 g is 15 inches in diameter when inflated with
helium at 735 torr and 75°F How much weight will the balloon lift in addition
to its own weight
9 (Assume the density of air to be 1 20 g/hter under these
conditions )
68 If the balloon of Problem 67 were filled with methane, CH 4 , at 735 torr and
75°F, would it rise
9 If so, how much additional weight would it lift
9
69 A mixture of N 2 and H 2 has a density of 0 267 g/hter at 700 torr and 30°C For
this mixture, calculate (a) the apparent molecular weight, (b) the percentage
composition by volume, and (c) the number of molecules in one ml
70 Show the mathematical steps needed in order to combine Boyle s and
Charles' laws to give Equation 11-2 on p 159
71 Use the methods of calculus to combine Boyle's and Charles' laws to give
Equation 11-2 on p 159
Gases
61 Two or three millihters of a liquid that boils at about 60°C are put into an
Erlenmeyer flask The flask is closed with a polystyrene stopper that has a fine
glass capillary running through it The gas-containing part of the flask is then
completely immersed in a bath of boiling water, which (at the elevation of the
experiment) boils at 98 8°C After a short time the air has been completely
swept out through the capillary, and the excess liquid has boiled away, leaving the flask filled only with the vapor of the liquid At this point the flask is
removed from the boiling water and cooled The vapor condenses to liquid
and air rushes in to fill the flask again The flask, when dry and empty had
weighed 39 5762 g, after the experiment it weighs 40 3183 g The barometric
pressure during the experiment is 730 torr The volume of the flask is determined by filling the flask with water, inserting the stopper to its previous
position, and squeezing out the excess water through the capillary The vol
ume of water so held is 239 6 ml What is the mole weight of the liquid'
62 The liquid used in Problem 61 is analyzed and found to be 24 2% C, 4 05% H,
and 71 7% Cl What is the true molecular formula of this liquid
1
63 An automobile tire has a gauge pressure of 35 0 lb/m
j when the atmospheric
pressure is 14 7 lb/m
2 and the temperature is 40°F What will be its gauge
pressure if its temperature rises to 120°F
9
64 Hydrogen chloride effuses through a hole (under prescribed conditions of
temperature and pressure) at the rate of 2 70 ml/mm At what velocity will
helium effuse through the same hole under the same conditions'
65 It takes 45 sec for a given volume of CO to effuse through a pinhole under
given conditions of temperature and pressure How long will it take for the
same volume of Br 2 vapor to effuse through the same hole under the same
conditions
9
66 Under certain prescribed conditions, O 2 effuses through a pinhole at the rate
of 3 65 ml/mm A mixture of CO and CO 2 effuses through the same pinhole
under the same conditions at the rate of 3 21 ml/mm Calculate the percentage
of CO in the gas mixture
67 A rubber balloon weighing 10 g is 15 inches in diameter when inflated with
helium at 735 torr and 75°F How much weight will the balloon lift in addition
to its own weight
9 (Assume the density of air to be 1 20 g/hter under these
conditions )
68 If the balloon of Problem 67 were filled with methane, CH 4 , at 735 torr and
75°F, would it rise
9 If so, how much additional weight would it lift
9
69 A mixture of N 2 and H 2 has a density of 0 267 g/hter at 700 torr and 30°C For
this mixture, calculate (a) the apparent molecular weight, (b) the percentage
composition by volume, and (c) the number of molecules in one ml
70 Show the mathematical steps needed in order to combine Boyle s and
Charles' laws to give Equation 11-2 on p 159
71 Use the methods of calculus to combine Boyle's and Charles' laws to give
Equation 11-2 on p 159