unit of pressure; 1 atm = 101,325 Pa

(bar or b) unit of pressure; 1 bar = 100,000 Pa

device used to measure atmospheric pressure

pressure exerted by a fluid due to gravity

device used to measure the pressure of a gas trapped in a container

SI unit of pressure; 1 Pa = 1 N/m^2

pounds per square inch (psi)

unit of pressure common in the US

unit of pressure; $\text{1 torr} = \ \frac{1}{760} \ \text{atm}$

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Chemistry 2e · 9.1 Gas Pressure

Gas Pressure: practice problems

9 problems from the book, with its answers. Check your working, or have any of them explained to you on the whiteboard.

Exercises 1
Why are sharp knives more effective than dull knives? (Hint: Think about the definition of pressure.)
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Exercises 3
Why should you roll or belly-crawl rather than walk across a thinly-frozen pond?
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Exercises 5
A typical barometric pressure in Denver, Colorado, is 615 mm Hg. What is this pressure in atmospheres and kilopascals?
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Exercises 7
Canadian tire pressure gauges are marked in units of kilopascals. What reading on such a gauge corresponds to 32 psi?
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Exercises 9
The pressure of the atmosphere on the surface of the planet Venus is about 88.8 atm. Compare that pressure in psi to the normal pressure on earth at sea level in psi.
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Exercises 11
Consider this scenario and answer the following questions: On a mid-August day in the northeastern United States, the following information appeared in the local newspaper: atmospheric pressure at sea level 29.97 in. Hg, 1013.9 mbar.
(a) What was the pressure in kPa?
(b) The pressure near the seacoast in the northeastern United States is usually reported near 30.0 in. Hg. During a hurricane, the pressure may fall to near 28.0 in. Hg. Calculate the drop in pressure in torr.
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Exercises 13
The pressure of a sample of gas is measured at sea level with a closed-end manometer. The liquid in the manometer is mercury. Determine the pressure of the gas in:
(a) torr
(b) Pa
(c) bar
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Exercises 15
The pressure of a sample of gas is measured at sea level with an open-end mercury manometer. Assuming atmospheric pressure is 760.0 mm Hg, determine the pressure of the gas in:
(a) mm Hg
(b) atm
(c) kPa
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Exercises 17
How would the use of a volatile liquid affect the measurement of a gas using open-ended manometers vs. closed-end manometers?
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Key terms · 9

atmosphere (atm): unit of pressure; 1 atm = 101,325 Pa
bar: (bar or b) unit of pressure; 1 bar = 100,000 Pa
barometer: device used to measure atmospheric pressure
hydrostatic pressure: pressure exerted by a fluid due to gravity
manometer: device used to measure the pressure of a gas trapped in a container
pascal (Pa): SI unit of pressure; 1 Pa = 1 N/m^2
pounds per square inch (psi): unit of pressure common in the US
pressure: force exerted per unit area
torr: unit of pressure; $\text{1 torr} = \ \frac{1}{760} \ \text{atm}$

Learn 9.1 on the whiteboard

The tutor teaches the whole section, drawing it out step by step and answering your questions as you go.

Read 9.1 in the textbook · This section on openstax.org

Gas Pressure: practice problems

9 problems from the book, with its answers. Check your working, or have any of them explained to you on the whiteboard.

Exercises 1

Why are sharp knives more effective than dull knives? (Hint: Think about the definition of pressure.)

Exercises 3

Why should you roll or belly-crawl rather than walk across a thinly-frozen pond?

Exercises 5

A typical barometric pressure in Denver, Colorado, is 615 mm Hg. What is this pressure in atmospheres and kilopascals?

Exercises 7

Canadian tire pressure gauges are marked in units of kilopascals. What reading on such a gauge corresponds to 32 psi?

Exercises 9

The pressure of the atmosphere on the surface of the planet Venus is about 88.8 atm. Compare that pressure in psi to the normal pressure on earth at sea level in psi.

Exercises 11

Consider this scenario and answer the following questions: On a mid-August day in the northeastern United States, the following information appeared in the local newspaper: atmospheric pressure at sea level 29.97 in. Hg, 1013.9 mbar.

(a) What was the pressure in kPa?

(b) The pressure near the seacoast in the northeastern United States is usually reported near 30.0 in. Hg. During a hurricane, the pressure may fall to near 28.0 in. Hg. Calculate the drop in pressure in torr.

Exercises 13

The pressure of a sample of gas is measured at sea level with a closed-end manometer. The liquid in the manometer is mercury. Determine the pressure of the gas in:

(a) torr

(b) Pa

A diagram of a closed-end manometer is shown. To the upper left is a spherical container labeled, “gas.” This container is connected by a valve to a U-shaped tube which is labeled “closed end” at the upper right end. The container and a portion of tube that follows are shaded pink. The lower portion of the U-shaped tube is shaded grey with the height of the gray region being greater on the right side than on the left. The difference in height of 26.4 c m is indicated with horizontal line segments and arrows.

Exercises 15

The pressure of a sample of gas is measured at sea level with an open-end mercury manometer. Assuming atmospheric pressure is 760.0 mm Hg, determine the pressure of the gas in:

(a) mm Hg

(b) atm

A diagram of an open-end manometer is shown. To the upper left is a spherical container labeled, “gas.” This container is connected by a valve to a U-shaped tube which is labeled “open end” at the upper right end. The container and a portion of tube that follows are shaded pink. The lower portion of the U-shaped tube is shaded grey with the height of the gray region being greater on the left side than on the right. The difference in height of 13.7 c m is indicated with horizontal line segments and arrows.

Exercises 17

How would the use of a volatile liquid affect the measurement of a gas using open-ended manometers vs. closed-end manometers?

Key terms · 9

atmosphere (atm): unit of pressure; 1 atm = 101,325 Pa
bar: (bar or b) unit of pressure; 1 bar = 100,000 Pa
barometer: device used to measure atmospheric pressure
hydrostatic pressure: pressure exerted by a fluid due to gravity
manometer: device used to measure the pressure of a gas trapped in a container
pascal (Pa): SI unit of pressure; 1 Pa = 1 N/m^2
pounds per square inch (psi): unit of pressure common in the US
pressure: force exerted per unit area
torr: unit of pressure; $\text{1 torr} = \ \frac{1}{760} \ \text{atm}$

Learn 9.1 on the whiteboard

The tutor teaches the whole section, drawing it out step by step and answering your questions as you go.

Read 9.1 in the textbook · This section on openstax.org