168
Gases
12 (a) What volume will 0 500 g of O 2 occupy at 750 torr and 26°C over water*
7
(b) What volume will it occupy if collected over mercury at the same conditions
9
13 A sample of NaNO 2 is tested for purity by heating it with an excess of NH 4 C1
and collecting the evolved N 2 over water The volume collected is 567 3 ml at
a barometric pressure of 741 torr The temperature is 22°C What volume
would the nitrogen, dry, occupy at standard conditions
7
14 What is the weight of 250 ml of N 2 measured at 740 torr and 25°C
7
15 What volume will be occupied by I 00 g of O 2 measured over water at 27°C
and 730 torr
7
16 What is the molecular weight of a gas if 250 ml measured over water at 735 torr
and 28°C weighs 1 25 g
9
17 What is the density of chlorine gas (C1 2 ) at 83°F and 723 torr
7
18 Calculate the density of N 2 O (a) at standard conditions, (b) at 730 torr and
25°C, dry
19 It is found experimentally that 0 563 g of a vapor at 100°C and 725 torr has a
volume of 265 ml Find the molecular weight
20 A compound has the formula CgH 18 What volume will 1 00 g of this material
have at 735 torr and 99°C
9
21 What is the apparent mole weight of a gas mixture composed of 20 0% H 2 ,
70 0% CO 2 , and 10 0% NO
9 (Composition given is percentage by volume )
22 An oxygen-containing gas mixture at 1 00 atm is subjected to the action of
yellow phosphorus, which removes the oxygen In this way it is found that
oxygen makes up 35 0% by volume of the mixture What is the partial
pressure of O 2 in the mixture
17
23 A mixture of gases contained in a vessel at 0 500 atm is found to comprise
15 0% N 2 , 50 0% N 2 O, and 35 0% CO 2 by volume
(a) What is the partial pressure of each gas
9
(b) A bit of solid KOH is added to remove the CO 2 Calculate the resulting
total pressure, and the partial pressures of the remaining gases
24 A vessel whose volume is 235 0 ml, and whose weight evacuated is 13 5217 g
+ a tare vessel, is filled with an unknown gas at a pressure of 725 torr and a
temperature of 19°C It is then closed, wiped with a damp cloth, and hung in the
balance case to come to equilibrium with the tare vessel The tare vessel has
about the same surface area and is needed to minimize surface moisture
effects This second weighing is 13 6109 g + the tare vessel What is the mole
weight of the gas
7
25 Two or three millihters of a liquid that boils at about 50°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 99 2°C After a short time the air has been completely
Gases
12 (a) What volume will 0 500 g of O 2 occupy at 750 torr and 26°C over water*
7
(b) What volume will it occupy if collected over mercury at the same conditions
9
13 A sample of NaNO 2 is tested for purity by heating it with an excess of NH 4 C1
and collecting the evolved N 2 over water The volume collected is 567 3 ml at
a barometric pressure of 741 torr The temperature is 22°C What volume
would the nitrogen, dry, occupy at standard conditions
7
14 What is the weight of 250 ml of N 2 measured at 740 torr and 25°C
7
15 What volume will be occupied by I 00 g of O 2 measured over water at 27°C
and 730 torr
7
16 What is the molecular weight of a gas if 250 ml measured over water at 735 torr
and 28°C weighs 1 25 g
9
17 What is the density of chlorine gas (C1 2 ) at 83°F and 723 torr
7
18 Calculate the density of N 2 O (a) at standard conditions, (b) at 730 torr and
25°C, dry
19 It is found experimentally that 0 563 g of a vapor at 100°C and 725 torr has a
volume of 265 ml Find the molecular weight
20 A compound has the formula CgH 18 What volume will 1 00 g of this material
have at 735 torr and 99°C
9
21 What is the apparent mole weight of a gas mixture composed of 20 0% H 2 ,
70 0% CO 2 , and 10 0% NO
9 (Composition given is percentage by volume )
22 An oxygen-containing gas mixture at 1 00 atm is subjected to the action of
yellow phosphorus, which removes the oxygen In this way it is found that
oxygen makes up 35 0% by volume of the mixture What is the partial
pressure of O 2 in the mixture
17
23 A mixture of gases contained in a vessel at 0 500 atm is found to comprise
15 0% N 2 , 50 0% N 2 O, and 35 0% CO 2 by volume
(a) What is the partial pressure of each gas
9
(b) A bit of solid KOH is added to remove the CO 2 Calculate the resulting
total pressure, and the partial pressures of the remaining gases
24 A vessel whose volume is 235 0 ml, and whose weight evacuated is 13 5217 g
+ a tare vessel, is filled with an unknown gas at a pressure of 725 torr and a
temperature of 19°C It is then closed, wiped with a damp cloth, and hung in the
balance case to come to equilibrium with the tare vessel The tare vessel has
about the same surface area and is needed to minimize surface moisture
effects This second weighing is 13 6109 g + the tare vessel What is the mole
weight of the gas
7
25 Two or three millihters of a liquid that boils at about 50°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 99 2°C After a short time the air has been completely