Dampfdruck und Siedepunkt

Messung der Änderung des Dampfdrucks mit der Temperatur

Gas Laws Advanced (University) 45 Min. ~$12,00

Ziel

Den Dampfdruck von Wasser bei verschiedenen Temperaturen messen und die Clausius-Clapeyron-Gleichung überprüfen.

Hintergrund

The vapor pressure of a liquid increases exponentially with temperature. By measuring the temperature at which water boils under different reduced pressures (or measuring vapor pressure at different temperatures), the enthalpy of vaporization can be determined from the Clausius-Clapeyron equation.

Sicherheitswarnungen

  • Handle vacuum apparatus carefully — implosion risk with glass
  • Hot water can cause burns
  • Use proper vacuum-rated glassware only

Erforderliche PSA

goggles lab_coat

Materialien

  • Distilled water (200 mL)
  • Ice (500 g)
    For cold water bath

Ausrüstung

Round-bottom flask (500 mL) Vacuum pump or syringe Pressure gauge or manometer Thermometer Hot plate Rubber tubing Graph paper

Durchführung

1

Set up the flask with water, thermometer, and pressure gauge. Connect to the vacuum pump.

5 Min. Use vacuum-rated glassware only
2

Heat the water to 80°C. Record the temperature and vapor pressure.

5 Min.
3

Reduce pressure with the vacuum pump. Note the temperature at which boiling begins.

5 Min.
4

Record at least 8 temperature-pressure data points from 40°C to 100°C.

15 Min.
5

Plot ln(P) vs 1/T(K). The slope = -ΔHvap/R.

10 Min.
6

Calculate ΔHvap from the slope. Compare with the literature value of 40.7 kJ/mol.

5 Min.

Erwartete Ergebnisse

The ln(P) vs 1/T plot should be linear with a negative slope. The calculated ΔHvap should be approximately 40-44 kJ/mol, close to the accepted value of 40.7 kJ/mol for water.

Aufräumen

Release vacuum slowly. Turn off heater. Drain water and dry apparatus.

Details

Kategorie
Gas Laws
Schwierigkeit
Advanced (University)
Dauer
45 Min.
Geschätzte Kosten
$12,00
Schritte
6
Materialien
2

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Frequently Asked Questions

What is the objective of Dampfdruck und Siedepunkt?
Den Dampfdruck von Wasser bei verschiedenen Temperaturen messen und die Clausius-Clapeyron-Gleichung überprüfen.
How difficult is Dampfdruck und Siedepunkt?
This experiment is rated as Advanced (University). It takes approximately 45 minutes to complete.
What safety precautions are needed for Dampfdruck und Siedepunkt?
Key safety precautions include: Handle vacuum apparatus carefully — implosion risk with glass; Hot water can cause burns; Use proper vacuum-rated glassware only.
What materials are needed for Dampfdruck und Siedepunkt?
The main materials required are: Distilled water, Ice.
What results should I expect from Dampfdruck und Siedepunkt?
The ln(P) vs 1/T plot should be linear with a negative slope. The calculated ΔHvap should be approximately 40-44 kJ/mol, close to the accepted value of 40.7 kJ/mol for water.