Shenzhen University Physical Chemistry Experiment Report

Experimenter: Lai Kaitao, Zhang Zhicheng, Shi Wei Tang Feifei

Shenzhen University Physical Chemistry Experiment Report

Experimenter: Lai Kaitao Experimental Time: May 15

Temperature: 23.0 ° C Atmospheric pressure: 100900Pa

Experiment 6: Two-liquid system gas----liquid equilibrium phase diagram

One: purpose requirements

Draw the gas-liquid equilibrium diagram of the pentane-ethanol two-liquid system in p, understand the basic concept of phase diagram and phase rate. Master the method to determine the boiling point of two-component liquid system. Master the determination of binary liquid with refractive index. Method of composition

Two: instrument reagent

Three: data analysis

Four: Experimental discussion.

When the boiling point is measured, the solution is overheated or fractionated, what changes will occur in the drawn phase diagram?

A: When the solution is overheated or fractionated, the boiling point will be high, so the plotted phase diagram will shift upwards.

Both the pressure and temperature measurements have random errors, and the error transfer expression of H is derived.

A: It is available from the definition of H, H=U+PV.

→ dH=dU+PdV+VdP

→ dH=v dT+TdV+pdV+Vdp

→ ΔVHm=VΔT+VΔp

Discuss the main sources of error in this experiment.

Answer: The main source of this experiment: the composition of the liquid phase produced by heating the two-liquid system is not fixed, and the heating time is not very fixed, so the refractive index of the measurement is inaccurate. In addition, the position of the thermometer mercury ball is not fixed, and sometimes it is closer to the heating wire, and the measured temperature is slightly higher.

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Shenzhen University Physical Chemistry Experiment Report

Experimenter: Zhang Zhicheng Experimental time: May 15

Temperature: 23.0 ° C Atmospheric pressure: 100900Pa

Experiment 6: Two-liquid system gas----liquid equilibrium phase diagram

One: purpose requirements

Draw the gas-liquid equilibrium diagram of the pentane-ethanol two-liquid system in p, understand the basic concept of phase diagram and phase rate. Master the method to determine the boiling point of two-component liquid system. Master the determination of binary liquid with refractive index. Method of composition

Two: instrument reagent

Experimental discussion.

When the boiling point is measured, if the solution is overheated or fractionated, will the pattern of the phase diagram be changed?

A: When the solution is overheated or fractionated, the boiling point will be high, so the plotted phase diagram will shift upwards.

Discuss the main sources of error in this experiment.

A: The main source of this experiment is that the composition of the liquid phase produced by heating the two-liquid system is not fixed, but depends on the length of time of heating, thus causing an error in the measured refractive index.

Third, the choice of the system to be tested The system selected for this experiment, the boiling point range is more appropriate. It can be seen from the phase diagram that there is a serious deviation between the system and the Ural law. As a minimum worthy phase diagram, the system has some typical meaning. However, the liquid phase of the phase diagram is relatively flat, and it is impossible to accurately plot the entire phase diagram within a limited number of hours.

Fourth, the design of the boiling point analyzer instrument must be convenient for the determination of the boiling point and gas-liquid two-phase composition. The design of the steam condensing section is one of the keys. If the volume of the concave hemisphere collecting the condensate is too large, the solution will be fractionally distilled in an objective manner; and if it is too small, the amount of the back will be too small to bring certain difficulties to the measurement. If the connection between the line condensation and the round bottom flask is too short or too low, the boiling liquid may splash into the ball; on the contrary, it may cause the higher boiling component to be condensed first. Come, the gas phase sample composition will be biased. In the Chinese labor experiment, the equilibrium, measured temperature and gas-liquid phase composition data measured by Ross equilibrium can be used, and the effect is good.

5. The composition measurement can be determined by relative density or other methods, but the measurement of the refractive index is quick and simple, in particular, the sample is required to be small, but in order to reduce the error, the measurement is usually repeated three times. When the refractive index of the sample changes little with the composition, the measurement error of this method is large.

6. Why do industries often produce 95% alcohol? Is it possible to obtain anhydrous alcohol only by rectifying the aqueous alcohol?

A: For various reasons, under this condition, the product obtained by distillation can only get 95% alcohol. It is impossible to obtain anhydrous alcohol by only rectifying aqueous alcohol. 95% alcohol also contains 5% water, which is an azeotrope with boiling point. The boiling point is still the same proportion of components, so use The fractionation method cannot remove 5% of water. Industrially, anhydrous ethanol is prepared by first adding a certain amount of benzene and then performing distillation.

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Shenzhen University Physical Chemistry Experiment Report

Experimenter: Shi Yan Tang Feifei Experimental time: 2000/5/17

Temperature: 24.2 °C Atmospheric pressure: 100.80 kPa

Drawing of two-component solid-liquid phase diagram

Objective To measure the phase diagram of lead-tin binary metal by thermal analysis, to understand the basic characteristics of solid-liquid phase diagram, to learn the production of thermocouple, to calibrate and measure the temperature to master the use of automatic balance recorder.

Instruments and reagents

Automatic balance recorder, thermocouple, electric furnace, mud triangle, crucible pliers, pure Sn, SnPb alloy with Sn 20%, 40%, 60%, and 80% and pure Pb

Experimental data and its processing

4 Experimental discussion.

When the boiling point is measured, if the solution is overheated or fractionated, will the pattern of the phase diagram be changed?

A: When the solution is overheated or fractionated, the boiling point will be high, so the plotted phase diagram will shift upwards.

Discuss the main sources of error in this experiment.

A: The main source of this experiment is that the composition of the liquid phase produced by heating the two-liquid system is not fixed, but depends on the length of time of heating, thus causing an error in the measured refractive index.