-TRANSPARENCY MASTER Text Reference: Section 11-4

U-Tube Manometer, Problem 1

air pressure « 101.3 kPa (760 mm Hg)ivalve

containerof gas

mercury

Assuming that the valve is open, what pressure, inkilopascals, is the gas exerting?

•

11-4 CHEMISTRY: The Study of Matter COPYRIGHT by Prentice Hall Inr

760 mm Hg+ 40mmHg=800mmHg800X101.3/760= 106 Kpa

TRANSPARENCY MASTER

U-Tube Manometer, Problem 2

Text Reference: Section 11-4

air pressure * 101.3 kPa (760 mm Hg)icontainer

of gas

mercury

Assuming that the valve is open, what pressure, inkilopascals, 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

760mmHg- 40mmHg = 720mm Hg

720 mmHg x 101.3 Kpa/760 mmHg=95.96 Kpa

TRANSPARENCY MASTER— - * '\ '

Text Reference: 'Section 11-4 «T*.

, U-Tube Manometer, Problem 3

air pressurein open end

1. When the valve is opened, will the mercury in theright arm of the U-tube move up or down?

2. After the mercury stops moving, what will be thedifference in height of the mercury levels in thetwo arms of the tube?

11-6 CHEMISTRY The Study of Mattel COPYRIGHT by Prennce Hall, Inc

P atm

UP

104.4 Kpa -99.75 Kpa= 4.65 Kpa

4.65Kpa x 760 mm Hg/ 101.3Kpa = 34.89 mm Hg

Measuring PressureBarometers and open-ended manometers are devices used to meas-ure pressure. In a barometer, the height of a column of mercury (inmillimeters) equals the atmospheric pressure, in millimeters of mer-cury. (1 mm Hg = 0.133 kPa).

The tube of an open-ended manometer is open, at one end, to theatmosphere. Therefore, atmospheric pressure is being exerted on thecolumn of mercury in that arm of the tube. If the height of the mer-cury in the open arm is greater than that in the other arm, the differ-ence between the two heights must be added to the atmosphericpressure to find the pressure of the confined gas, in mm Hg. If theheight in the open arm is Jess than that in the other arm, the differ-ence 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

kPafactor 0.133 —.mm Hg

Refer to the figures below in answering the following questions.

750 mm

atmospheric pressure= 101.3 kPa

atmospheric pressure= 100.4 kPa

atmospheric pressure= 101.7kPa

/ confined ^—s confinedV 600 mm V 9*S

325 mm<150 mm

(0

500 mm

1. What is the atmospheric pressure, in kPa, indicated by the baro- 1.meter in Figure A?2. What is the pressure, in kPa, of the confined gas as indicated by 2.the open-ended manometer in Figure B?3. What is the pressure, in kPa, of the confined gas indicated by the 3.open-ended manometer in Figure C?4. What is the pressure, in kPa, of the confined gas indicated by the 4.open-ended manometer in Figure D?

750 mm X 101.3 Kpa/760 mm = 99.97Kpa

400mmHg + 760 mmHg= 1160

equals 760 mm Hg

100.4 Kpa-

175 mmHg

(175mmHg X 101.3 Kpa/760 mmHg760)+ = 77.7

Kpa

400mmHg

101.7 Kpa + (400 mmHg x 101.3 Kpa/760 mmHg) = 155 Kpa