CN104458507A - Method for measuring surface tension coefficient of liquid by injecting liquid into round tank - Google Patents

Abstract

The method for measuring the surface tension coefficient of a liquid by injecting liquid into a circular groove involves the measurement of physical parameters. The circular groove is composed of two cylinders with the same central axis and a common sealing bottom plate, and there is a small hole in the sealing bottom plate of the circular groove. Place the circular groove on a table, the small hole of the circular groove is suspended outside the table, place a measuring cup under the small hole, take the liquid with a volume of Q1 and pour it into the circular groove, and let it stand for a while. When there is no liquid dripping below the hole, read the volume Q2 of the liquid from the measuring cup, measure the inner radius r _of the outer cylinder and the outer radius r _of the inner cylinder, and the surface tension coefficient of the liquid is σ=[ρ*(Q1-Q2) *g]/[2π*(r _outside +r _inside )]. The beneficial effect is: if the accuracy of measuring mass or volume is high enough, the maximum error of the device is the gravity generated by the mass of a droplet, so the error is small; the structure is simple and the cost is low.

Description

Method for measuring liquid surface tension coefficient by injecting liquid into circular groove

technical field

The invention relates to the measurement of physical parameters, especially the measurement of the surface tension coefficient of liquids.

Background technique

Common methods for measuring the surface tension coefficient of liquids are: maximum bubble pressure method, capillary method, pull-off method, etc. The measurement method is either complicated, such as the maximum bubble pressure method, pull-off method; or the measurement accuracy is not high, although the capillary method is simple , but the liquid surface is curved, and the height of the liquid column is not accurate enough. Since the liquid surface outside the capillary also rises along the tube wall outside the capillary, it is difficult to determine the coordinate value of the horizontal position of the liquid surface, which leads to the determination of the inside of the capillary. The height difference of the liquid column is more difficult.

Contents of the invention

The invention proposes a novel surface tension measurement method.

Technical scheme of the present invention is:

The structure of the measuring device: the circular groove is composed of two cylinders with the same central axis and a common sealing bottom plate, the outer side of the inner cylinder, the inner side of the outer cylinder and the upper part of the sealing bottom plate constitute the effective function of the circular groove There is a small hole on the sealing bottom plate of the circular groove, and the small hole is a through hole.

Measurement method 1: Place the circular groove on a table with a leveling bubble on the table and a level adjustment device on the base. The small hole of the circular groove is suspended outside the table. Place a measuring cup under the small hole and take a certain amount Pour the liquid into the circular groove, set the volume of the liquid as Q1, the amount of the liquid should ensure that there is liquid dripping under the small hole, wait until there is no liquid dripping under the small hole, read from the measuring cup below the small hole Find the volume Q2 of the liquid dripping from the small hole in the measuring cup, measure the inner radius r _of the outer cylinder and the outer radius r _of the inner cylinder, then the surface tension coefficient of the liquid is σ=[ρ*(Q1- Q2)*g ]/[2π*(r _outside + r _inside )], where σ is the surface tension coefficient of the liquid, ρ is the density of the liquid, g is the acceleration of gravity, and π is the circumference ratio.

Measurement method 2: Measure the inner radius r _of the outer cylinder and the outer radius r _of the inner cylinder, then place the circular groove on the measuring table of an electronic balance, align the center of the circular groove with the center of the measuring table, and adjust The base of the balance makes the level bubble of the balance indicate a horizontal state. The small hole is suspended outside the measuring table, and the mass m1 is recorded when there is no liquid inside the circular groove. A measuring cup is placed under the small hole, and a certain amount of liquid is poured into it. The amount of the liquid should ensure that there is liquid dripping under the small hole, and when there is no liquid dripping under the small hole, record the total amount of the circular groove and the liquid adhered inside the circular groove. Mass m2, then the surface tension coefficient of the liquid is σ=[(m2- m1)*g]/[2π*(r _outside + r _inside )], where σ is the surface tension coefficient of the liquid, g is the acceleration of gravity, and π is the circumference ratio.

The beneficial effects of the present invention are: surface tension absorbs liquid inside the circular groove, and the liquid part exceeding the surface tension adsorption capacity seeps out from the small hole at the bottom to form a droplet below the small hole. As the liquid gradually seeps out, When the weight of the droplet is greater than the surface tension (σ*L) generated by the circle of the droplet in contact with the lower surface (set the circumference as L), the droplet will drop into the measuring cup below the small hole; When the surface tension inside the groove can absorb the weight of all the liquid inside the circular groove, the liquid will stop seeping out, and no liquid will drop into the measuring cup or other containers under the small hole. At this time, the state below the small hole is flat or there is a suspended droplet, therefore, if the accuracy of measuring mass or volume is high enough, the maximum error of this device is the gravity generated by the mass of a droplet, so the error is small; the surface tension absorbs the mass of liquid It can be obtained by multiplying the density of the liquid (check the temperature and density correspondence table) and the volume (obtained from the change in the volume of the graduated cylinder), or by directly measuring the increment of its mass through the balance; the measuring device has a simple structure and low measurement cost .

Description of drawings

Fig. 1 is a schematic diagram of a circular groove, and Fig. 2 is a schematic diagram of a longitudinal section of a circular groove.

Among them, 1. the circular groove, 2. the small hole, r the inner radius of _{the outer} and outer cylinders, r the outer radius of _{the inner} and inner cylinders.

Detailed ways

The circular groove 1 is composed of two cylinders with the same central axis and a common sealing bottom plate. The outer side of the inner cylinder, the inner side of the outer cylinder and the upper part of the sealing bottom plate form the space of the circular groove 1. There is a small hole 2 on the sealing bottom plate of the circular groove 1, and the small hole 2 is a through hole; the circular groove 1 is placed on a table (the table has a horizontal bubble, and the base has a level adjustment device), and the small hole 2 is in the Place a measuring cup under the small hole 2, take a certain amount of liquid and pour it into the circular groove 1. Let the volume of the liquid be Q1. The amount of the liquid should ensure that there is liquid dripping from the bottom of the small hole 2. , stand still until there is no liquid dripping below the small hole 2, read the volume Q2 of the liquid dripping from the small hole 2 in the measuring cup from the measuring cup, measure _the inner radius r of the outer cylinder and the outer radius r _of the inner cylinder, The value of the radius can also be obtained by measuring the diameter, then the liquid surface tension coefficient is σ=[ρ*(Q1-Q2)*g]/[2π*(r _outside + r _inside )], where σ is the liquid surface tension coefficient , ρ is the density of the liquid (it can be obtained by consulting the density table of the liquid according to the ambient temperature), g is the acceleration of gravity, and π is the circumference ratio.

It is also possible to place the circular groove 1 on the measuring table of an electronic balance (the center of the circular groove 1 is aligned with the center of the measuring table), adjust the base of the balance so that the level bubble of the balance indicates a horizontal state, and the balance generally has a level The base has level adjustment feet, the small hole 2 of the circular groove 1 is suspended outside the measuring table (a diameter r _outside is greater than the radius R of the measuring table, for example, r _outside = 2R is possible), record the circular groove 1 mass m1, place a measuring cup or other container under the small hole 2, take a certain amount of liquid and pour it into the circular groove 1, the amount of the liquid should ensure that there is liquid dripping from the bottom of the small hole 2, let stand When there is no liquid dripping under the small hole 2, record the total mass m2 of the circular groove 1 and the liquid adhered inside the circular groove 1, then the surface tension coefficient of the liquid is σ=[(m2- m1)*g] /[2π*(r _outside + r _inside )], where σ is the surface tension coefficient of the liquid, g is the acceleration of gravity, and π is the circumference ratio.

Claims (2)

1. The method for measuring the surface tension coefficient of a liquid by injecting liquid into a circular groove is characterized in that: the circular groove is composed of two cylinders with the same central axis and a common sealing bottom plate, the outer side of the inner cylinder, the outer The inner side of the cylinder and the upper part of the sealing bottom plate constitute the effective space of the circular groove, and there is a small hole on the sealing bottom plate of the circular groove, which is a through hole; the circular groove is placed on a table, and the table There is a horizontal bubble, and the base has a level adjustment device to make the table level. The small hole of the circular groove is suspended outside the table. A measuring cup is placed under the small hole, and a certain amount of liquid is poured into the circular groove. The volume is Q1, the amount of the liquid should ensure that there is liquid dripping from the bottom of the small hole, and when there is no liquid dripping from the bottom of the small hole, read the volume of the liquid dripping from the small hole in the measuring cup from the measuring cup below the small hole Q2, measure the _inner radius r of the outer cylinder and the outer radius r _of the inner cylinder, then the surface tension coefficient of the liquid is σ=[ρ*(Q1- Q2)*g]/[2π*(r _outer + r _inner )] , where σ is the surface tension coefficient of the liquid, ρ is the density of the liquid, g is the acceleration of gravity, and π is the circumference ratio. 2. A method for measuring liquid surface tension coefficient by injecting liquid into a simplified circular groove, characterized in that: the circular groove is made up of two cylinders with the same central axis and a common sealing bottom plate, and the inner cylinder The outer side of the outer cylinder, the inner side of the outer cylinder and the upper part of the sealing bottom plate constitute the effective space of the circular groove, and there is a small hole on the sealing bottom plate of the circular groove, which is a through hole; measure _the inner radius r of the outer cylinder and the outer radius r _of the inner cylinder; place the circular groove on the measuring platform of an electronic balance, align the center of the circular groove with the center of the measuring platform, adjust the base of the electronic balance so that the level bulb of the balance indicates a horizontal state, The small hole is suspended outside the measuring table, and the mass m1 is recorded when there is no liquid inside the circular groove. A measuring cup or other container is placed under the small hole, and a certain amount of liquid is poured into the circular groove. The amount should ensure that there is liquid dripping under the small hole, and when there is no liquid dripping under the small hole, record the total mass m2 of the circular groove and the liquid adhered inside the circular groove, then the surface tension coefficient of the liquid is σ =[(m2- m1)*g]/[2π*(r _outside + r _inside )], where σ is the coefficient of surface tension of the liquid, g is the acceleration of gravity, and π is the circumference ratio.