experimental report

Experimenter: Han Fei Chen Haixing He Yuehui Qiu Xuehui

Experiment 3: Determination of saturated vapor pressure of liquid

Experimenter: Chen Haixing. Han Fei Experimental Time: 2000/5/29

Temperature: 22.4 °C Atmospheric pressure: 100.923 kPa

First, the purpose and requirements of the experiment:

1. Defining the definition of pure liquid saturated vapor pressure and the concept of gas-liquid two-phase equilibrium, and understanding the relationship between pure liquid saturated vapor pressure and temperature? Clausius-Clapeyron equation.

2. Determine the saturated vapor pressure of benzene at different temperatures with an isobaric meter. Initially master the vacuum test technology.

3. Learn to use the graphic method to find the average molar heat of vaporization and normal boiling point of the liquid to be tested in the experimental temperature range.

Second, instruments and reagents:

Third, data records and processing:

Fourth, the experimental discussion

First, the pressure and temperature measurements have random errors, try to derive the error transfer expression of H.

A: Available from H=U+PV,

→ dH=dU+PdV+VdP

→ dH=v dT+TdV+pdV+Vdp

→ ΔVHm=VΔT+VΔp

Second, with this device, it is convenient to study various liquids, such as benzene, dichloroethylene, carbon tetrachloride, water, n-propanol, isopropanol, acetone, ethanol, etc. Many of these liquids are flammable. What should I pay attention to when heating?

Answer: When heating, the flammable objects should not be too close to the heater. The heater should be heated evenly. When taking the medicine, avoid spreading it on the heater. When using these medicines, cover it.

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Experiment 3: Determination of saturated vapor pressure of liquid

Experimenter: Chen Haixing. Han Fei Experimental Time: 2000/5/29

Temperature: 22.4 °C Atmospheric pressure: 100.923 kPa

First, the purpose and requirements of the experiment:

1. Defining the definition of pure liquid saturated vapor pressure and the concept of gas-liquid two-phase equilibrium, and understanding the relationship between pure liquid saturated vapor pressure and temperature? Clausius-Clapeyron equation.

2. Determine the saturated vapor pressure of benzene at different temperatures with an isobaric meter. Initially master the vacuum test technology.

3. Learn to use the graphic method to find the average molar heat of vaporization and normal boiling point of the liquid to be tested in the experimental temperature range.

Second, instruments and reagents:

Third, data records and processing:

Fourth, the experimental discussion

First, the pressure and temperature measurements have random errors, try to derive the error transfer expression of H.

A: Available from H=U+PV,

→ dH=dU+PdV+VdP

→ dH=v dT+TdV+pdV+Vdp

→ ΔVHm=VΔT+VΔp

Second, with this device, it is convenient to study various liquids, such as benzene, dichloroethylene, carbon tetrachloride, water, n-propanol, isopropanol, acetone, and ethanol. Many of these liquids are flammable. What should I pay attention to when heating?

Answer: When heating, the flammable objects should not be too close to the heater. When taking the medicine, avoid sprinkling it on the heater. When using these medicines, cover it.

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Experiment 1, Determination of saturated vapor pressure of liquid

Experimenter: He Yuehui Experimental time: 2000/5/17

Temperature: 22.5 °C Atmospheric pressure: 100.85kPa

First, the purpose and requirements of the experiment:

1. Defining the definition of pure liquid saturated vapor pressure and the concept of gas-liquid two-phase equilibrium, and understanding the relationship between pure liquid saturated vapor pressure and temperature - Clausius-Clapeyron equation.

2. Determine the saturated vapor pressure of benzene at different temperatures with an isobaric meter. Initially master the vacuum test technology.

3. Learn to use the graphic method to find the average molar heat of vaporization and normal boiling point of the liquid to be tested in the experimental temperature range.

Second, instruments and reagents:

Third, data records and processing:

Room temperature: 22.5 °C

Atmospheric pressure p0: 100.85, 100.88, 100.83, 100.87 kPa

Average atmospheric pressure: 100.86 kpa

The boiling point of benzene measured at atmospheric pressure: 76.18 degrees Celsius.

Fourth, thinking questions:

First, the pressure and temperature measurements have random errors, try to derive the error transfer expression of H.

A: Available from H=U+PV,

→ dH=dU+PdV+VdP

→ dH=v dT+TdV+pdV+Vdp

→ ΔVHm=VΔT+VΔp

Second, with this device, it is convenient to study various liquids, such as benzene, dichloroethylene, carbon tetrachloride, water, n-propanol, isopropanol, acetone, and ethanol. Many of these liquids are flammable. What should I pay attention to when heating?

Answer: When heating, it should be heated slowly, and the temperature should be carefully controlled so that the temperature of the solution should not exceed the ignition point of the liquid to be tested. At the same time, there should be no air above the liquid level of the a and c tubes, and the temperature change should be gradually reduced.

Fifth, the experimental discussion:

The air in the balance tubes a and b must be driven away before the measurement. The cooling rate should not be too fast, otherwise the measured temperature will deviate from the equilibrium temperature. If the air is poured during the experiment, the experiment must be redone. When stopping the experiment, the three-way piston should be slowly opened first, the system is opened to the atmosphere, and then the pump is taken to the atmosphere, then the power is turned off, and finally the cooling water is turned off to restore the device.

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Determination of saturated vapor pressure of liquids

The purpose of the experiment is to define the definition of pure liquid saturated vapor pressure and the concept of gas-liquid two-phase equilibrium. To understand the relationship between saturated vapor pressure and temperature of pure liquid. The relationship between the saturated vapor pressure and the temperature of the liquid is determined. The Crablon equation is used to determine the cyclohexane at different temperatures. Saturated vapor pressure. Initially grasp the vacuum test technology society to use the graphic method to find the average molar heat of vaporization and normal boiling point of the measured liquid in the experimental temperature range.

Instruments and reagents

Experimental procedure

1. Prepare for work. Turn on the cooling water. Recognize the role of each cock in the system. Turn on the air intake cock to open the system to the atmosphere. Read the atmospheric pressure p0. Read every half hour later.
2. System leak detection. Turn on the vacuum pump, turn on the suction cock after 2 minutes, close the air intake cock, depressurize the system to a mercury column difference of about 500 mm, and close the suction cock. If the system does not change the mercury column within 5 minutes, the system will not leak.
3. Plug in the power supply of the heater, controller and agitator, start the agitator, turn on the controller power switch, and adjust the temperature control knob to 52 °C to warm the water bath.
4. After the temperature of the water bath rises to 52 ° C, the temperature of the water bath is accurately read. Slowly rotate the intake cock so that the bc two liquid level in the balance tube is equal, and read the height of the two mercury columns on the left and right of the U-shaped differential pressure gauge.
5. Determine the saturated vapor pressure of the liquid at 52, 56, 60, 65, 70, 73, and 76 ° C, respectively.
6. The system passes through the atmosphere and measures the boiling point of the liquid at local atmospheric pressure.
7. After the experiment is completed, disconnect the power supply and water source.

data record

Room temperature: 22.5 ° C

Atmospheric pressure p0: 100.85, 100.88, 100.83, 101.1 kPa

Serial number

1

2

3

4

5

6

7

h left mmHg

633.5

604.5

581.1

541.8

515.2

507.1

486.5