TRANSPARENCY MASTER
Text Reference: Section 11-4
U-Tube Manometer, Problem 1
760 mm Hg+ 40mmHg=800mmHg
800X101.3/760= 106 Kpa
air pressure « 101.3 kPa (760 mm Hg)
valve
i
container
of gas
mercury
Assuming that the valve is open, what pressure, in
kilopascals, is the gas exerting?
•
11-4
CHEMISTRY: The Study of Matter
COPYRIGHT by Prentice Hall Inr
TRANSPARENCY MASTER
Text Reference: Section 11-4
U-Tube Manometer, Problem 2
air pressure * 101.3 kPa (760 mm Hg)
i
760mmHg- 40mmHg = 720mm Hg
container
of gas
720 mmHg x 101.3 Kpa/760
mmHg=
95.96 Kpa
mercury
Assuming that the valve is open, what pressure, in
kilopascals, is the gas exerting?
^
COPYRIGHT by Prentice Mill, Inc.
Reproduction of thu matter n reitncted to duplication for claiiroom u»e only
CHEMISTRY: The Study of Matter
11-5
—
TRANSPARENCY MASTER
-
* '\
'
Text Reference: 'Section 11-4
«T*.
, U-Tube Manometer, Problem 3
air pressure
in open end
P atm
1. When the valve is opened, will the mercury in the
UP
right arm of the U-tube move up or down?
2. After the mercury stops moving, what will be the 104.4 Kpa -99.75 Kpa= 4.65 Kpa
difference in height of the mercury levels in the
two arms of the tube?
4.65Kpa x 760 mm Hg/ 101.3Kpa = 34.89 mm Hg
11-6
CHEMISTRY The Study of Mattel
COPYRIGHT by Prennce Hall, Inc
Measuring Pressure
Barometers and open-ended manometers are devices used to measure pressure. In a barometer, the height of a column of mercury (in
millimeters) equals the atmospheric pressure, in millimeters of mercury. (1 mm Hg = 0.133 kPa).
The tube of an open-ended manometer 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, in mm Hg. If the
height in the open arm is Jess than that in the other arm, the difference in height must be subtracted from the atmospheric pressure.
After you have calculated the pressure in millimeters of mercury,
convert the answer to kilopascals by multiplying by the conversion
kPa
factor 0.133
—.
mm Hg
Refer to the figures below in answering the following questions.
equals
atmospheric pressure
= 101.3 kPa 760 mm
atmospheric pressure
= 100.4 kPa
atmospheric pressure
= 101.7kPa
Hg
750 mm
/ confined ^—s
confined
V 600 mm
V
9 S
*
325 mm<
175
mmHg
500 mm
400mmHg
150 mm
(0
1. What is the atmospheric pressure, in kPa, indicated by the barometer in Figure A?
2. What is the pressure, in kPa, of the confined gas as indicated by
the open-ended manometer in Figure B?
750 mm X 101.3 Kpa/760 mm = 99.97Kpa
1.
2.
400mmHg + 760 mmHg= 1160
3. What is the pressure, in kPa, of the confined gas indicated by the
3.
(175mmHg
X 101.3 Kpa/760 mmHg760)
100.4 Kpaopen-ended manometer in Figure C?
= 77.7
+
Kpa
4. What is the pressure, in kPa, of the confined gas indicated by the
4.
open-ended manometer in Figure D?
101.7 Kpa + (400 mmHg x 101.3 Kpa/760 mmHg) = 155 Kpa