Vapour pressure of water below 100°C - molar heat of vaporisation  ![]()
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Principle The vapour pressure of water in the range of 40 °C to 85 °C is
investigated. It is shown that the Clausius-Clapeyron equation
describes the relation between temperature and pressure in an
adequate manner. An average value for the heat of vaporisation of
water is determined. Benefits - Compact, easily transportable setup
- For both demonstration and student experiments
- No gas burner required - Easy to operate and no consumption of consumables
- No open flame in the setup - Reduction of thermal hazard
Tasks - About 250 ml of demineralised water are allowed to boil for
about 10 minutes to eliminate all traces of dissolved gas. The
water is then cooled down to room temperature.
- The 3-neck round flask is filled about three-quarters full with
gas-free water and heated. At 35 °C the space above the water
within the round flask is evacuated. Further heating causes an
increase in pressure p and temperature T of water within the
round flask. p and T are read in steps of 5 °C up to a maximum
of T = 85 °C.
Learning objectives - Pressure
- Temperature
- Volume
- Vaporization
- Vapour pressure
- Clausius-Clapeyron equation
Scope of delivery |
Manometer -1.0...0.6 bar
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03105-00
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1
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Students thermometer,-10...+110°C, l = 180 mm
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38005-02
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2
| |
Three-neck round bottom flasks, various volumes
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MAU-27220501
|
1
| |
Stopcock,1-way,r.-angled, glass
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36705-01
|
1
| |
Rotary valve vacuum pump, two stages, 115 V / 230 V
|
02741-95
|
1
| |
Hotplate magnetic stirrer with connection for electronic contact thermometer, 3 ltr., 230 V
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35760-93
|
1
| |
Magnetic stirring bar 30 mm, cylindrical
|
46299-02
|
2
| |
Gasket for GL25, 8mm hole, 10 pcs
|
41242-03
|
1
| |
Vacuum tube, NBR, 6/14mm, 1 m
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39289-00
|
2
| |
Tripod base, triangular, for 6 rods
|
02007-55
|
1
| |
Stand rods, stainless steel, various sizes
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02033-00
|
1
| |
Stand rods, stainless steel, various sizes
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02059-00
|
1
| |
Universal clamp with joint
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37716-00
|
2
| |
Right angle clamp expert with fulcrum screw
|
02054-00
|
2
| |
Beakers, Boro, low form, various sizes
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46055-00
|
1
| |
Beakers, Boro, low form, various sizes
|
46056-00
|
1
|
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