蒸气压与沸点

测量蒸气压随温度的变化

Gas Laws Advanced (University) 45 分钟 ~$12.00

目标

测量不同温度下水的蒸气压，验证克劳修斯-克拉佩龙方程。

背景

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.

安全警告

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

所需PPE

goggles lab_coat

材料

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

设备

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

步骤

1

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

5 分钟 Use vacuum-rated glassware only
2

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

5 分钟
3

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

5 分钟
4

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

15 分钟
5

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

10 分钟
6

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

5 分钟

预期结果

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.

清理

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

详情

类别
Gas Laws
难度
Advanced (University)
时长
45 分钟
预估费用
$12.00
步骤数
6
材料
2

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Frequently Asked Questions

What is the objective of 蒸气压与沸点?
测量不同温度下水的蒸气压，验证克劳修斯-克拉佩龙方程。
How difficult is 蒸气压与沸点?
This experiment is rated as Advanced (University). It takes approximately 45 minutes to complete.
What safety precautions are needed for 蒸气压与沸点?
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 蒸气压与沸点?
The main materials required are: Distilled water, Ice.
What results should I expect from 蒸气压与沸点?
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.