CN104406891A - Method for measuring surface tension coefficient of liquid through liquid drainage of semi-spherical shell - Google Patents

Abstract

The invention relates to the measurement of physical parameters, in particular to a method for measuring the surface tension coefficient of a liquid through liquid drainage of a semi-spherical shell. The method adopts the technical scheme that the spherical shell outside radius of the semi-spherical shell is R, and the average density of the semi-spherical shell is 0.5 to 0.8 time of the liquid density; the liquid is injected into an overflow trough until the liquid overflows to a cup at the lower end of a guide trench through the guide trench at the upper edge of the overflow trough; when the liquid stops dripping at the tail end of the guide trench, the mass m1 of the cup is measured, and the cup is then placed right below the tail end of the guide trench; the mass m of the semi-spherical shell is measured; the semi-spherical shell is slowly placed into the overflow trough in a manner that the opening of the semi-spherical shell is upward, the liquid flows into the cup at the tail end of the guide trench, the mass m2 of the cup accommodating the liquid is measured when no liquid drips at the tail end of the guide trench, and the liquid surface tension is [m-(m2-m1)] * g; the surface tension coefficient of the liquid sigma=[m-(m2-m1)]*g/(2*pi*R2), and R2 is the radius of the contact circle of the liquid level and the spherical shell. The method has the benefits of being simple in structure, low in cost and easy in operation.

Description

Hemispherical Shell discharging liquid measures the method for liquid surface tension coefficient

Technical field

The present invention relates to the measurement of the measurement of physical parameter, particularly liquid surface tension coefficient.

Background technology

The method measuring liquid surface tension coefficient common are: largest air bubbles platen press, capillary tube technique, Pulling escape etc., measuring method or device more complicated, such as largest air bubbles platen press, Pulling escape; The precision measured is not high, although capillary tube technique is simple, but liquid level bends, the insufficient height measuring fluid column is accurate, because the liquid level outside kapillary also rises along the tube wall outside kapillary, therefore, more difficult at the coordinate figure of the horizontal level determining liquid level, thus cause the difference in height of the fluid column determined inside kapillary more difficult.

Summary of the invention

The present invention proposes a kind of novel method for surface tension measurement.

Technical scheme is: hemispherical Shell discharging liquid measures the method for liquid surface tension coefficient, it is characterized in that: a hemispherical Shell, radius outside its spherical shell is R, the bottom of hemispherical Shell is thick, upper end is thin, bottom centre's thickness is 3-10 times of hemispherical Shell edge of opening thickness, and its center of gravity offsets to the bottom of hemispherical Shell; The quality m that the average density of hemispherical Shell is hemispherical Shell and the hemisphere volume that hemispherical Shell outside surrounds are 2 π R ³/ 3 are divided by, average density=m/ (2 π R ³/ 3), the average density of hemispherical Shell is 0.5-0.8 times of fluid density, and fluid density herein refers to the maximal density of a normal atmosphere pressure maintenance medium state; An overflow groove, liquid is injected to overflow groove, until the curb of overflow groove upper end-face edge has overflow to the water tumbler of curb lower end, the end of curb is bent downwardly, the liquid being conducive to overflow groove spilling flows in water tumbler, when the end of curb stops drop of liquid, the liquid rotating of water tumbler is moved on to fluid reservoir, measure the quality m1 of water tumbler, then water tumbler is placed on immediately below curb end; Measure the quality m of hemispherical Shell, make hemispherical Shell opening up, hemispherical Shell is put in overflow groove lentamente, the object slowly put into will guarantee that liquid level there will not be wave and curb end to there will not be Liquid inject, slowly overflow groove is put into along with hemispherical Shell, the end of curb has liquid to flow into water tumbler, finally decontrol hemispherical Shell, by the time when curb end does not have liquid to drip, measure the quality m2 that accommodate the water tumbler of liquid, then the surface tension of liquid is [m-(m2-m1)] * g, and wherein g is acceleration of gravity; The part of liquid comes into contact hemispherical Shell is a spherical crown, and spherical crown is a face, does not have volume, and the part that spherical crown encloses is called segment, and the volume V computing formula of segment is V=(π/3) * (3R-h) * h ², in formula, R is the radius of ball, and h is the height of segment, according to law of buoyancy, the quality of spherical crown institute discharging liquid should equal the quality of hemispherical Shell, i.e. ρ * V=m, wherein ρ is the density of liquid, thus calculates h, calculates meniscus liquid contact hemispherical Shell place radius of a circle R2=[R by h ²-(R-h) ²] ^ ^0.5, then 2* π * R2* σ=[m-(m2-m1)] * g, wherein σ is the surface tension coefficient of liquid, then σ=[m-(m2-m1)] * g/ (2* π * R2).

Beneficial effect is: the bottom of hemispherical Shell is thick, upper end is thin, can be designed as bottom centre's thickness be the 3-10 of upper end open edge thickness doubly, its center of gravity offsets to the bottom of hemispherical Shell, is conducive to strengthening its stability, and that reduces that it puts into that liquid produces rocks; Regulate relative to the difficulty of prior art, high cost, structure of the present invention is simple, with low cost, processing ease.

Accompanying drawing explanation

Fig. 1 is hemispherical Shell schematic diagram, Fig. 2 hemispherical Shell elevational schematic, and Fig. 3 is overflow groove and water tumbler schematic diagram, and Fig. 4 is spherical crown schematic diagram.

Wherein, 1, hemispherical Shell, 2, hemispherical Shell opening, 3, overflow groove, 4, curb, 5, water tumbler.

Embodiment

A hemispherical Shell 1, the radius of its outside spherical shell is R, owing to being hemispherical Shell, namely the outer radius of the circle at hemispherical Shell opening 2 place is R, the bottom of hemispherical Shell 1 is thick, upper end is thin, deformation occurs in inside hemispherical Shell, outside is the spherical of standard, and as shown in Figure 2, namely its center of gravity offsets to the bottom of hemispherical Shell 1; The volume (hemisphere volume) of the quality m that the average density of hemispherical Shell 1 is hemispherical Shell 1 and the segment that hemispherical Shell 1 outside surrounds is 2 π R ³/ 3 are divided by, average density=m/ (2 π R ³/ 3), the average density of hemispherical Shell 1 is less than the density of liquid, and best value is 0.5-0.8 times of fluid density, due to fluid density larger change along with temperature variation has, along with pressure change is relatively little, fluid density herein refers to the maximal density of a normal atmosphere pressure maintenance medium state.

An overflow groove 3, radius inside overflow groove 3 is that the 1.5-2 of hemispherical Shell 1 outer radius is doubly for best, liquid is injected to overflow groove 3, until the curb 4 of overflow groove 3 upper end-face edge has overflow to the water tumbler 5 of curb lower end, the end of curb 4 is bent downwardly, and the liquid being conducive to overflow groove 3 spilling flows in water tumbler 5.When the end stopping drop of liquid of curb 4, the liquid rotating of water tumbler is moved on to fluid reservoir (relative to the measurement range of balance, when the amount of liquid is less, also can not transfer liquid), measure the quality m1 of water tumbler 5, immediately below the end then water tumbler 5 being placed on curb 4; Measure the quality m of hemispherical Shell, hemispherical Shell opening 2 is made to put in overflow groove 3 lentamente upward, by hemispherical Shell 1, the object slowly put into there will not be wave and curb 4 end to there will not be Liquid inject in order to ensure liquid level, overflow groove 3 is slowly put into along with hemispherical Shell 1, the end of curb 4 has liquid to flow into water tumbler, finally decontrol hemispherical Shell 1, by the time when curb 4 end does not have liquid to drip, measure the quality m2 that accommodate the water tumbler 5 of liquid, then the surface tension of liquid is [m-(m2-m1)] * g, and wherein g is acceleration of gravity.

For capillary understanding, an object swims on liquid level, its buoyancy equals the weight of object, due to capillary effect, for can by the object of liquid-soaked, liquid be understood some and is adhered to body surface, and the liquid volume of the inflow water tumbler arranged by floating body should be the part of below liquid level, the liquid level at this place does not refer to the liquid level with object contact place, but away from the liquid level of contact position.According to law of buoyancy, the volume V arranged and the fluid density ρ ρ * V that is multiplied is equal with the quality m of object, but due to capillary effect, a part liquid higher than liquid level height and stick on object, in the present invention, this part liquid does not flow out by curb 4, and the quality of this part is m-(m2-m1).

The part of liquid comes into contact hemispherical Shell 1 is a spherical crown, and spherical crown is a face, does not have volume.The part that spherical crown encloses is called segment (referring to Fig. 4).The volume computing formula of segment is V=(π/3) * (3R-h) * h ²in formula, R is the radius of ball, h is the height of segment, according to law of buoyancy, the quality of spherical crown institute discharging liquid should equal the quality of hemispherical Shell 1, and namely ρ * V=m(should be ρ * V=m2-m1 herein, because surface tension is less, m is approximately m2-m1), thus calculate h, calculate meniscus liquid by h and contact hemispherical Shell 1 place radius of a circle R2=[R ²-(R-h) ²] ^ ^0.5, then 2* π * R2* σ=[m-(m2-m1)] * g, wherein σ is the surface tension coefficient of liquid, and g is acceleration of gravity, then σ=[m-(m2-m1)] * g/ (2* π * R2).

For pure water, the surface tension coefficient of 20 degrees Celsius is 0.073N/m, and wherein N/m is Newton/meter, if R gets 10.00cm, average density gets 0.5g/cm ³then m=1047 gram, h=6.53cm, R2=9.37cm, surface tension is 2* π * R2* σ=0.0429N, when acceleration of gravity removes 10N/Kg, then surface tension is equivalent to the gravity suffered by 4.29 gram masses, i.e. m-(m2-m1)=4.29 gram, electronic balance in current laboratory or other balance can both measure such a difference (4.29 grams), such as, network can inquire precise electronic balance-JH3102, range: 3100g, precision: 10mg(that is 0.01 gram), therefore, the present invention has exploitativeness.

Claims (1)

1. hemispherical Shell discharging liquid measures the method for liquid surface tension coefficient, and it is characterized in that: a hemispherical Shell (1), its spherical shell outer radius is R, and the bottom of hemispherical Shell (1) is thick, upper end is thin, and its center of gravity offsets to the bottom of hemispherical Shell (1), the quality m that the average density of hemispherical Shell (1) is hemispherical Shell (1) and the hemisphere volume that hemispherical Shell (1) outside surrounds are 2 π R ³/ 3 are divided by, average density=m/ (2 π R ³/ 3), the average density of hemispherical Shell (1) is 0.5-0.8 times of fluid density, and fluid density herein refers to the maximal density of a normal atmosphere pressure maintenance medium state, an overflow groove (3), liquid is injected to overflow groove (3), until the curb (4) of overflow groove (3) upper end-face edge has overflow to the water tumbler (5) of curb lower end, the end of curb (4) is bent downwardly, being conducive to the liquid that overflow groove (3) overflows flows in water tumbler (5), when the end of curb (4) stops drop of liquid, the liquid rotating of water tumbler (5) is moved on to fluid reservoir, measure the quality m1 of water tumbler (5), then water tumbler (5) is placed on immediately below curb (4) end, measure the quality m of hemispherical Shell, make hemispherical Shell opening (2) upward, hemispherical Shell (1) is put into lentamente in overflow groove (3), the object slowly put into will guarantee that liquid level there will not be wave and curb (4) end to there will not be Liquid inject, overflow groove (3) is slowly put into along with hemispherical Shell (1), the end of curb (4) has liquid to flow into water tumbler, finally decontrol hemispherical Shell (1), by the time when curb (4) end does not have liquid to drip, measure the quality m2 that accommodate the water tumbler (5) of liquid, then the surface tension of liquid is [m-(m2-m1)] * g, wherein g is acceleration of gravity, the part of liquid comes into contact hemispherical Shell (1) is a spherical crown, and spherical crown is a face, does not have volume, and the part that spherical crown encloses is called segment, and the volume V computing formula of segment is V=(π/3) * (3R-h) * h ², in formula, R is the radius of ball, and h is the height of segment, according to law of buoyancy, the quality of spherical crown institute discharging liquid should equal the quality of hemispherical Shell (1), i.e. ρ * V=m, wherein ρ is the density of liquid, thus calculates h, calculates meniscus liquid contact hemispherical Shell (1) place radius of a circle R2=[R by h ²-(R-h) ²] ^ ^0.5, then 2* π * R2* σ=[m-(m2-m1)] * g, wherein σ is the surface tension coefficient of liquid, then σ=[m-(m2-m1)] * g/ (2* π * R2).