Name: ____________________________________________Per: ____ Date: ____
Measuring Pressure
Barometers and open- and closed-end manometers are devices used to measure pressure. The closedend manometer (Figure B) is used to measure the actual pressure of a confined gas. There is a
vacuum above the column of mercury in the closed end of the manometer tube. The pressure, in torr,
of the confined gas equals the difference, in millimeters, between the heights of the mercury in the
two vertical arms of the tube.
The tube of the open-end manometer (Figure C) is open, at one end, to the atmosphere.
Therefore, atmospheric pressure is being exerted on the column of mercury in that arm of the tube. If
the height of the mercury in the open arm is greater than that in the other arm, the difference between
the two heights must be added to the atmospheric pressure to find the pressure of the confined gas. If
the height in the open arm is less than that in the other arm, the difference in height must be
subtracted from the atmospheric pressure.
Refer to the figures below in answering the following questions.
1. What is the atmospheric pressure, in torr, indicated
by the barometer in Figure A?
2. What is the pressure, in torr, of the confined gas as
Indicated by the closed-end manometer in Figure B?
3. What is the pressure, in torr, of the confined gas
Indicated by the open-end manometer in Figure C?
4. What is the pressure, in torr, of the confined gas
Indicated by the open-end manometer in Figure D?
Gas Vocab
1. _______________
2. _______________
3. _______________
4. _______________
Word List
Atmosphere
Barometer
Manometer
Pascal
Pressure
State
Torr
Volume
Gases represent one of three phases of matter. Another word for “phase”
is ___ (1) ___. Gases have no definite shape, nor do they have a definite
___ (2) ___. The force exerted by a gas on a unit area is called __ (3) __. One Newton per square meter is a unit of
pressure called the __ (4) __. The pressure of a column of mercury one millimeter high is another unit of pressure, called
the __ (5) __.
Atmospheric pressure is most often measured by use of a (n) __ (6) __. A U-shaped tube called a (n) __ (7) __ can also be
used. Standard atmospheric pressure is 760 torr; this quantity is another unit of pressure, called one __ (8)__.
1. ________________ 3. _____________ 5. ____________ 7. ______________
2. ________________ 4. _____________ 6. ____________ 8. ______________