Pressão de Vapor e Ponto de Ebulição

Medição de como a pressão de vapor muda com a temperatura

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

Objetivo

Medir a pressão de vapor da água em diferentes temperaturas e verificar a equação de Clausius-Clapeyron.

Contexto

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.

Avisos de segurança

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

EPI necessário

goggles lab_coat

Materiais

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

Equipamentos

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

Procedimento

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

Resultados esperados

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.

Limpeza

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

Detalhes

Categoria
Gas Laws
Dificuldade
Advanced (University)
Duração
45 min
Custo estimado
$12,00
Passos
6
Materiais
2

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Frequently Asked Questions

What is the objective of Pressão de Vapor e Ponto de Ebulição?
Medir a pressão de vapor da água em diferentes temperaturas e verificar a equação de Clausius-Clapeyron.
How difficult is Pressão de Vapor e Ponto de Ebulição?
This experiment is rated as Advanced (University). It takes approximately 45 minutes to complete.
What safety precautions are needed for Pressão de Vapor e Ponto de Ebulição?
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 Pressão de Vapor e Ponto de Ebulição?
The main materials required are: Distilled water, Ice.
What results should I expect from Pressão de Vapor e Ponto de Ebulição?
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.