vapor pressure evaporation h 2 o(g) molecules (water vapor) h 2 o(l) molecules
TRANSCRIPT
![Page 1: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/1.jpg)
Evaporation
H2O(g)molecules
(water vapor)
H2O(l)molecules
![Page 2: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/2.jpg)
Evaporation
H2O(g)molecules
(water vapor)
H2O(l)molecules
![Page 3: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/3.jpg)
Evaporation
H2O(g)molecules
(water vapor)
H2O(l)molecules
![Page 4: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/4.jpg)
How Vapor Pressure is Measured
1 atm = 760 mm Hg
760 mm + 120 mm = 880 mm Hg
Animation by Raymond ChangAll rights reserved
![Page 5: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/5.jpg)
Manometer Atmospheric Pressure
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 401
![Page 6: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/6.jpg)
Manometer A
BIG = small + height
________ = small + __________
760 mm Hg
h = 120 mm
760 mm 120 mm
Small = 640 mm Hg
?
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 401
![Page 7: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/7.jpg)
Manometer B
BIG = small + height
BIG = ________ + _________ 760 mm 120 mm
BIG = 880 mm Hg
760 mm Hg
h = 120 mm
?
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 401
![Page 8: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/8.jpg)
The Manometer and Vapor Pressure
![Page 9: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/9.jpg)
Barometer & Manometer
atmospheric pressure = 101.3 kPa
atmospheric pressure = 100.4 kPa
atmospheric pressure = 101.7 kPa
confinedgas
confinedgas
confinedgas
600 mm
200 mm325 mm
150 mm 100 mm
500 mm
750 mm
(a) (b) (c) (d)
![Page 10: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/10.jpg)
Pressure and TemperatureSTST
PP (Standard Temperature and Pressure)
standard temperature standard pressure1 atm101.3 kPa760 mm Hg
273 K0oC
Equations / Conversion Factors:
K = oC + 273oC = K – 273
1 atm = 101.3 kPa = 760 mm Hg
![Page 11: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/11.jpg)
Convert 25oC to Kelvin.
K = oC + 273
How many mm Hg is 231.5 kPa?
How many kPa is 1.37 atm?
25oC + 273 298 K=
X kPa = 1.37 atm101.3 kPa
1 atm= 138.8 kPa
X mm Hg = 231.5 kPa760 mm Hg
101.3 kPa= 1737 mm Hg
![Page 12: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/12.jpg)
Pa
CONFINEDGAS
AIRPRESSURE
Hg HEIGHTDIFFERENCE
manometermanometer:: measures the
pressure of a confined gas
higherpressure
![Page 13: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/13.jpg)
101.3 kPa
Atmospheric pressure is 96.5 kPa;mercury height difference is 233 mm.
Find confined gas pressure, in atm.
SMALL + HEIGHT = BIGSMALL + HEIGHT = BIG
0.953 atm + 0.307 atm = X atm
X = 1.26 atm
96.5 kPa1 atm
+ 233 mm Hg760 mm Hg
1 atm= X atm
96.5 kPa + 233 mm Hg = X atm
233 mm Hg
96.5 kPa
X atm
BIG
small
1.26 atm
![Page 14: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/14.jpg)
Vapor Pressure
more“sticky”
less likely tovaporize
In general:LOW v.p.
not very“sticky”
more likely tovaporize
In general:HIGH v.p.
measure of the tendency for liquid particles to enter gas phase at a given temp.
a measure of “stickiness” of liquid particles to each other
NOT all liquids have same v.p. at same temp.
![Page 15: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/15.jpg)
0 20 40 60 80 1000
20
40
60
80
100
TEMPERATURE (oC)
PRESSURE (kPa)
CHLOROFORM
ETHANOL
WATER
Volatile substances evaporate easily (have high v.p.’s).
BOILING when vapor pressure = confining pressure (usually from atmosphere)
b.p. = 78oC
b.p. = 100oC
atmospheric pressure is 101.3 kPa
![Page 16: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/16.jpg)
Vapor Pressure
93.3
80.0
66.6
53.3
40.0
26.7
13.3
0 10 20 30 40 50 60 70 80 90 100
61.3oC 78.4oC 100oC
chlo
rofo
rm
ethy
l alc
ohol
water
Pre
ssur
e (K
Pa)
Temperature (oC)
101.3
![Page 17: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/17.jpg)
ETHANOL
WATER
AIR PRESSURE(~100 kPa)
VAPORPRESSURE
(~5 kPa)
VAPORPRESSURE
(~10 kPa)
BOILING when vapor pressure = confining pressure (usually from atmosphere)
At sea level and 20oC…
![Page 18: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/18.jpg)
ETHANOL
WATER
NETPRESSURE
(~95 kPa)
NETPRESSURE
(~90 kPa)
![Page 19: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/19.jpg)
Water Molecules in Liquid and
Steam
![Page 20: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/20.jpg)
Microscopic view of a liquid near its surface
The high energymolecules escapethe surface.
![Page 21: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/21.jpg)
Behavior of a liquid in a closed container
![Page 22: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/22.jpg)
Water rapidly boiling on a stove
![Page 23: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/23.jpg)
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
Pressure Cooker
![Page 24: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/24.jpg)
120oC
![Page 25: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/25.jpg)
Formation of a bubble is opposed by the pressure of the atmosphere
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 452
![Page 26: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/26.jpg)
Vapor Pressure
93.3
80.0
66.6
53.3
40.0
26.7
13.3
0 10 20 30 40 50 60 70 80 90 100
61.3oC 78.4oC 100oC
chlo
rofo
rm
ethy
l alc
ohol
water
Pre
ssur
e (K
Pa)
Temperature (oC)
101.3
![Page 27: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/27.jpg)
Boiling Point and Pressure
![Page 28: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/28.jpg)
Heating / Cooling Curve of Water
140
120
100
80
60
40
20
0
-20
Tem
pera
ture
(oC
)
Heat added at a constant rate
liquid water
water and steam
steam
ice andwater
ice
Heatin
g
Cooling
![Page 29: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/29.jpg)
Gas Collected Over Water
![Page 30: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/30.jpg)
Measuring the Vapor Pressure of a Liquid
Davis, Metcalfe, Williams, Castka, Modern Chemistry, 1999, page 376
![Page 31: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/31.jpg)
Gas Mixtures and Dalton’s
Law
![Page 32: Vapor Pressure Evaporation H 2 O(g) molecules (water vapor) H 2 O(l) molecules](https://reader035.vdocuments.us/reader035/viewer/2022081515/56649d985503460f94a82845/html5/thumbnails/32.jpg)
Gases Dissolved in Liquids