SU1401301A2 - Device for measuring pressure of saturated vapours of liquids - Google Patents

Abstract

The invention relates to a measuring technique and allows to expand the range of measured pressures by providing the ability to measure the pressure increase of the saturated vapor over the liquid when the liquid components dissolve in it. In the device the thermostatic jacket 3 covers the upper parts of the vertical gauge tubes 1a, 16 s closed upper ends in the shape of capillaries 2a, 26. The open ends of the tubes are pubescent in removable tanks 5a, 56 with liquid 6a, 66. The upper non-removable parts of the tanks are connected by a nozzle 7, through which The pressure is regulated above the fluid levels. Manometric tubes 1a, 16 have a common measuring scale 9 of the difference in solution and liquid levels. 1 il. (Oh (L

Description

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The invention relates to the field of pressure measurement, in particular, to devices for measuring the pressure of saturated vapor | of liquidities and for measuring the increase (decrease) of the pressure of saturated vapor above a liquid when solids and liquids dissolve in it, can be used as an educational tool. in the study of physical chemistry in universities, in research practice in the study of the thermodynamics of solutions, in particular 5 biological studies, as well as 3 factory laboratories for the analysis of plants and is a mustache rshenstvovaniem due zestnogo device of the authors. St. 1026024.

The purpose of the invention is to expand the range of measured pressures by providing the ability to measure the increase (decrease) in the pressure of saturated steam with liquid when the liquid or solid components dissolve in it.

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I This makes it possible to determine the concentration of the dissolved substance and other thermodynamic properties of the solution.

I The drawing shows a diagram of the proposed device.

The device can be designed similarly for several solutions by introducing an appropriate number of additional tanks with additional vertical tubes. Two vertical gauge tubes 1a and 16 with closed upper ends in the form of capillaries 2a and 26 in the upper part are covered by a common thermostating sheath 3, the lower open end of tube 1a is hermetically (using thin section 4a) immersed in a removable container 5a with solvent 6a, and the lower end of the tube 16 is hermetically (using a thin section 46) lowered into a removable tank 56 with a solution 66. A nozzle 7 connects both tanks in their upper non-removable part and is connected to the evacuating and measuring : Noah system. Manometric tubes 1a and 16 are equipped with a common measuring scale 9 of the difference in the levels of solution and liquid.

The total pressure above the liquid and solution levels in tanks 5a and 56 is regulated by a three-way valve 10 by pumping with a fore vacuum pump (not shown) and by starting air from the atmosphere through capillary 11 and is measured with a mercury manometer 12 or another pressure sensor. If there are other additional tanks, their upper fixed parts are connected by pipes between themselves and with the upper parts of tanks 5, and their additional vertical pipes together with tubes 1a and 16 are covered by a thermostating jacket 3.

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The device works as follows.

Preparation for work consists in thermostatting the gauge tubes 1a and 16, filling the lower removable parts of the tanks 5a and 56, connecting them to the device and pumping out (the valve 10 is open for pumping with a pump). The air pumped out of the gauge tubes 1a and 16 together with the vapor blows through the liquids. In parallel with the pumping from the interface, the liquid evaporates in the phase equilibrium volume of the manometric tubes 1a and 16. When pumping out, there is a progressive decrease in the air content in the manometric tubes 1a and 16. Then, check valve 10a is filled, for which to the atmosphere and let in air through capillaries 11. If the air is sufficiently removed from tubes 1a and 16, the compared liquids 6a and 66 must fill practically the entire volume of tubes 1a and 16 and capillaries 2a and 26. The smaller the remaining air bubbles in the capillaries, the better the pumped out. If necessary, pumping is repeated. Then carefully open the valve 10 for pumping out and set the level of liquid 6a and solution 66 by pumping approximately symmetrically with respect to the middle of the measuring scale 9.

The vapor pressure of a liquid is found from

Р Рвн - pgho,

where Rvn is the external pressure measured by a mercury manometer 12;

p is the density of the test liquid;

g is the acceleration of free fall;

ho is the height of the liquid column in the tube above the liquid level in the tank 5a.

The change in pressure of the vapor above the solution is found by the formula

DR pgAh,

where L is the difference between the pillars of the levels of liquid and solution in the manometric tubes 1a and 16, measured on a scale of 9.

Here it is assumed that for dilute solutions, the density of the solution is practically the same as the density of the liquid.

Compared to the determination of AP by independent measurement of vapor pressure above the liquid and solution (LR Rost-R

mercury gauges using two separate known devices, the proposed differential device gives a gain in accuracy and sensitivity by as many times as the density of mercury is greater than the density of a liquid (for water is 13.6 times), and the effect of increasing or decreasing vapor pressure over the solution is visually visible. on the scale of the instrument (high accuracy and demonstrability.).

Claims (1)

Invention Formula A device for measuring the pressure of saturated vapors of liquids according to ed. St. No. 1026024, characterized in that, in order to expand the range of measured pressures by providing an opportunity to measure the increase in the pressure of saturated vapor over a liquid when liquid components dissolve in it, additional tank with removable bottom tira sheath. with a part for the solution and an upper fixed part connected by a channel with the upper non-removable part of the liquid reservoir, an additional vertical tube with a closed upper end in the form of a capillary, the lower part of which is immersed in the solution, and the upper part is placed in a thermostating sheath, and placed between the ends of the vertical tubes located in the thermostat