Pression de Vapeur et Point d'Ébullition

Mesure de la variation de la pression de vapeur avec la température

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

Objectif

Mesurer la pression de vapeur de l'eau à différentes températures et vérifier l'équation de Clausius-Clapeyron.

Contexte

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.

Avertissements de sécurité

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

EPI requis

goggles lab_coat

Matériaux

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

Équipement

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

Procédure

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

Résultats attendus

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.

Nettoyage

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

Détails

Catégorie
Gas Laws
Difficulté
Advanced (University)
Durée
45 min
Coût estimé
$12,00
Étapes
6
Matériaux
2

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Frequently Asked Questions

What is the objective of Pression de Vapeur et Point d'Ébullition?
Mesurer la pression de vapeur de l'eau à différentes températures et vérifier l'équation de Clausius-Clapeyron.
How difficult is Pression de Vapeur et Point d'Ébullition?
This experiment is rated as Advanced (University). It takes approximately 45 minutes to complete.
What safety precautions are needed for Pression de Vapeur et Point d'Ébullition?
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 Pression de Vapeur et Point d'Ébullition?
The main materials required are: Distilled water, Ice.
What results should I expect from Pression de Vapeur et Point d'Ébullition?
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.