5.1.1 Properties of Gases

Question 1

Properties of Gases

Answer 1

• The molecules of a gas are very far apart, have a high velocity, and fill up the space in which they are contained.
• Gases are quantified using volume and pressure.
• Pressure can be measured using a mercury barometer or an open-ended manometer.

Question 2

note

Answer 2

• The molecules of a gas are very far apart. This makes gases very compressible.
• Unlike in solids and liquids, some of the molecules of a gas have a high velocity.
• The molecules of a gas fill up the space in which they are contained.
• Gases are quantified using volume and pressure.
• Volume is measured in units of liters(L). 1 L = 1000 cm3.
• Pressure is force(F) per unit area (A). The force exerted by the atmosphere at sea level is 14.7 pounds per square inch (psi), or 1 atmosphere(atm).
• Against a perfect vacuum, 1 atm pressure can push a column of water up 32 feet. A lower pressure would push the column of water to a lower height. A denser liquid, such as mercury, has a lower maximum height.
• Atmospheric pressure can be measured using a mercury barometer. At sea level, the mercury in the column will be pushed up 760 mm. This allows pressure to be measured in units of millimeters of mercury (mmHg), where 760 mmHg = 1 atm. Another unit of pressure is the torr, where 1 torr = 1 mmHg.
• The pressure of a gas sample can be measured using an open-ended manometer. The difference in height (in millimeters) between the mercury columns on the two sides of the manometer shows the difference in pressure from 760 mmHg (1 atm).

Question 3

You constructed an enormous manometer using water instead of mercury. The water level in the closed end is 18 ft, while the water level in the open end is 2 ft. If the external pressure is 1 atm, what is the pressure of the gas sample?

Answer 3

0.50 atm

Question 4

An increasing atmospheric pressure reading indicates that good weather is forecasted. For the barometer shown in the figure, how would the level of the mercury be changing for such a forecast?

Answer 4

the level of the mercury in the column will increase

Question 5

A manometer shows a mercury level of 225 mm Hg on the closed end of the tube and 108 mm Hg on the open end. If the atmospheric pressure is 760 torr, what is the pressure of the gas (in mm Hg or torr) in the closed end of the manometer?

Answer 5

643 torr

Question 6

If a gas exerts pressure of 2.25 atm, what is its pressure in millimeters of mercury?

Answer 6

1710 mm Hg

Question 7

Using the barometer shown in the figure, determine the pressure in terms of atmosphere.

Answer 7

0.576 atm

Question 8

A gas exerts a pressure of 823 torr, what is its pressure, in units of lb / in2?

Answer 8

15.9 lb / in^2

Question 9

In a chemical reaction, a gas has a final pressure of 1.37 atm. What is the equivalent pressure in units of torr?

Answer 9

1,040 torr

Question 10

Which of the following is not a unit of measurement for volume?

Answer 10

metric ton

Question 11

The volume occupied by a sample of gas is 5,780 cm3 of space. What is this volume in liters?

Answer 11

5.78 L

Question 12

Which of the following statements about gases is not true?

Answer 12

There are strong, attractive forces between gas molecules.