Understanding Table H and
Vapor Pressure
Take out your reference tables now
In a closed system, at a steady temperature a dynamic equilibrium is
reached. This is when the evaporation rate equals the condensation
rate. This is only possible in a closed system.
Corked
top
Air pressure outside bottle is
about 101.3 Pa, same inside
to start.
Condensation
(down arrows)
WATER
Evaporation (up arrows)
If the system is heated, more evaporation occurs,
until a new dynamic equilibrium is reached.
If it’s cooled, less evaporation will occur, until a new dynamic equilibrium is reached.
Corked
top
Air pressure outside still about 101.3 kPa,
inside the pressure is increasing.
WATER
Condensation
(down arrows)
Evaporation (up arrows)
The extra pressure inside that bottle is called the vapor pressure.
It’s added to the existing air pressure present from the start.
Corked
top
Air pressure outside still about 101.3 kPa,
inside the pressure is increasing.
WATER
Condensation
(down arrows)
Evaporation (up arrows)
The vapor pressure of water (part of table H)
101.3 kPa
Pressure
kPa
0
50
100
temperature, Centigrade degrees
The vapor pressure of water (part of table H)
Big black dot indicates the “normal
boiling point”, the BP at normal
pressure.
101.3 kPa
The curved line
indicates ALL
of the boiling
points of
water, at all
different
pressures.
Pressure
kPa
0
50
100
temperature, Centigrade degrees
The vapor pressure of water (part of table H)
H2O at these
pressures and
temperatures is a
101.3 kPa
LIQUID
H2O at these
pressures and
temperatures is a
Pressure
kPa
GAS
0
50
100
temperature, Centigrade degrees
Table H is the vapor pressure of 4 different compounds, water included. Only look at one
curve, or one liquid, at any time. Behind the curve is liquid. In front is a gas.
Table H is the vapor pressure of 4 different compounds, water included. Only look at one
curve, or one liquid, at any time. Behind the curve is liquid. In front is a gas.
Let’s talk ONLY
about water…
At each point,
what phase is
the water in?
1.
2
1
4
2.
3.
3
4.
Table H is the vapor pressure of 4 different compounds, water included. Only look at one
curve, or one liquid, at any time. Behind the curve is liquid. In front is a gas.
Let’s talk ONLY
about water…
At each point,
what phase is
the water in?
1. liquid
2
1
4
2. liquid
3. liquid
3
4. gas
At each point,
what is the vapor
pressure of water?
101.3 kPa + 40⁰C
75 kPa + 95⁰C
150 kPa + 110⁰C
20 kPa + 65⁰C
At each point,
what is the vapor
pressure of water?
101.3 kPa + 40⁰C
LIQUID
75 kPa + 95⁰C
GAS
150 kPa + 110⁰C
LIQUID
20 kPa + 65⁰C
GAS
13
At points
A, B, and C
What phase is
water?
What phase is
ethanoic acid?
A
C
B
What phase is
ethanol?
What phase is
propanone?
At points
A, B, and C
What phase is
water?
A liquid
B gas
C liquid
A
C
B
At points
A, B, and C
What phase is
ethanoic acid?
A
C
B
A liquid
B liquid
C liquid
At points
A, B, and C
What phase is
ethanol?
A
C
B
A liquid
B gas
C gas
At points
A, B, and C
What phase is
propanone?
A
C
B
A gas
B gas
C gas
How much
extra
pressure is
added to a
sealed flask
containing
water at
50⁰C?
(what’s the
vapor pressure
of water at
50⁰C?)