中国石油大学：最大压差法测定表面张力 Surface tension determination with the maximum differential pressure method

EXPERIMENT 1 油学 华东 Surface tension determination with the maximum differential pressure method ●●●●● Wang zeng bao 2012.11

Surface tension determination with the maximum differential pressure method Wang Zengbao 2012.11 EXPERIMENT 1

●●● ●●●● ●●●●● 1. Experimental purposes ●●●● ●●●●● ●●●● 1)Master the principles and methods of maximum differential pressure method for the determination of surface tension (2)Measure the surface tension of n-butyl alcohol solution and understand the concept of surface tension and influencing factors (Learn Gibbs equation and its applications

1. Experimental purposes (1)Master the principles and methods of maximum differential pressure method for the determination of surface tension. (2)Measure the surface tension of n-butyl alcohol solution, and understand the concept of surface tension and influencing factors. (3)Learn Gibbs equation and its applications

●●● ●●●● 2. Experimental principles ●●●●● ●●●● ●●●●● ●●●● Polyacrylamide can be synthesized from acrylamide triggered by ammonium persulfate: CONH CON Polyacrylamide can hydrolyze in alkaline solution, which generates partially hydrolyzed polyacrylamide -ICH2-CHfn yH,O+ NAoh- CONH -FCH2-CHixFCH2-CHtv-FCH2-CH1+(+zNH31 CONH 2 COOH COoNa

2. Experimental principles Polyacrylamide can be synthesized from acrylamide triggered by ammonium persulfate: Polyacrylamide can hydrolyze in alkaline solution, which generates partially hydrolyzed polyacrylamide: nCH2 CH CONH2 (NH4 ) 2 S2 O8 [CH2 CH] n CONH2 [CH2 CH] n CONH2 + yH2 O + zNaOH [CH2 CH] x CONH2 [CH2 CH] y COOH [CH2 CH]z COONa + (y + z)NH3

●●● ●●●● 2. Experimental principles ●●●●● ●●●● ●●●●● ●●●● 20 △P R △P— The additional pressure which is formed when the water drops down in the wide mouth bottle R>I R=工 R>I The surface tension 2 (N/m) 20, I(1):R-The curvature radius of the bubble

R P P R P 2 1 2 1        1 1 2 p r   = 2 2 2 p r   = 2 2 1 1 p p    =   （1） R P 2  = P R —The additional pressure which is formed when the water drops down in the wide mouth bottle —The curvature radius of the bubble —The surface tension （N/m） 2. Experimental principles

●●● ●●●● 2. Experimental principles ●●●●● ●●●● ●●●●● ●●●● 20 △P= R 20 20 R>I R=工 R>I Therefore, at the same temperature, once the aPl, AP2 are measured, and the IFT of the liquid(water) whose IfT is known is found out according to the temperature table, then we can calculate the ift of the unknown liquid from the formula

1 1 2 p r   = 2 2 2 p r   = 2 2 1 1 p p    =   Therefore, at the same temperature, once the ΔP1, ΔP2 are measured, and the IFT of the liquid(water) whose IFT is known is found out according to the temperature table,then we can calculate the IFT of the unknown liquid from the formula 。 （1） R P 2  = 2. Experimental principles

●●● ●●●● ●●●●● 3.Apparatus and reagents ●●●● ●●●●● ●●●● Apparatus One set of device to measure the ift with the method of maximum differential pressure Bottle rubber pipette bulb. Reagents N-butyl alcohol (analytically pure), distilled water

3.Apparatus and reagents ⚫ Apparatus ⚫ One set of device to measure the IFT with the method of maximum differential pressure,Bottle, rubber pipette bulb. ⚫ Reagents ⚫ N-butyl alcohol (analytically pure), distilled water

●●● ●●●● ●●●●● 4. Experimental procedures ●●●● ●●●●● ●●●● .(1)Wash the external case and the capillary tube of the instrument used to measure surface tension with lotion. First add a little lotion into the external case rotation it inclined so that the lotion can contact with the external case( be careful not to let the lotion outflow from the side of the tube).Then insert the capillary tube and maintain the inclined external case still Rotate the capillary tube to make the lotion contact with the capillary tube Adsorb some lotion with the rubber pipette bulb to the capillary tube to wash the inside of the capillary tube. Pull the spent lotion to its original bottle and wash the external case and the capillary tube with running water fully. Finally, wash the external case and the capillary tube with distilled water three times respectively. Then we can go on with the following experiences

4.Experimental procedures ⚫ (1)Wash the external case and the capillary tube of the instrument used to measure surface tension with lotion. First add a little lotion into the external case,rotation it inclined so that the lotion can contact with the external case(be careful not to let the lotion outflow from the side of the tube).Then insert the capillary tube and maintain the inclined external case still.Rotate the capillary tube to make the lotion contact with the capillary tube.Adsorb some lotion with the rubber pipette bulb to the capillary tube to wash the inside of the capillary tube.Pull the spent lotion to its original bottle and wash the external case and the capillary tube with running water fully.Finally,wash the external case and the capillary tube with distilled water three times respectively.Then we can go on with the following experiences

●●● ●●●● ●●●●● 4. Experimental procedures ●●●● ●●●●● ●●●● .(2) Put some distilled water into the external case(regard as liquid of known IFT. See Appendix ll to get its surface tension). Insert the capillary tube into the external case and plug the plug tightly and let the tip of the capillary tube touch the liquid surface exactly. read out the zero level ho of the tube beneath the inclined tube manometer (at this point both ends of the inclined tube manometer connect with the atmosphere). Install the device according to figure2 1, where the separatory funnel is filled with tap water

4.Experimental procedures ⚫ (2)Put some distilled water into the external case(regard as liquid of known IFT. See Appendix II to get its surface tension).Insert the capillary tube into the external case and plug the plug tightly and let the tip of the capillary tube touch the liquid surface exactly.Read out the zero level h0 of the tube beneath the inclined tube manometer(At this point both ends of the inclined tube manometer connect with the atmosphere).Install the device according to figure2- 1,where the separatory funnel is filled with tap water

●●● ●●●● ●●●●● 4. Experimental procedures ●●●● ●●●●● ●●●● (3)Open the piston of the separatory funnel to let the water in it drip slowly into the wild-mouth bottle Then the pressure inside the bottle increase gradually and bubbles will pass through the end of the capillary tube. o Read out the highest level h1 from the inclined tube manometer when the first bubble pass through it. Repeat the same procedures three times and calculate the average value h2

4.Experimental procedures ⚫ (3)Open the piston of the separatory funnel to let the water in it drip slowly into the wild-mouth bottle.Then the pressure inside the bottle increase gradually and bubbles will pass through the end of the capillary tube. ⚫ Read out the highest level h1 from the inclined tube manometer when the first bubble pass through it.Repeat the same procedures three times and calculate the average value h2

●●● ●●●● ●●●●● 4. Experimental procedures ●●●● ●●●●● ●●●● Drain the distilled after the maximum differential pressure has been measured. Wash the external case and the capillary tube once with butanol with the concentration of 0. 002molL Then add the solution and measure its maximum differential pressure just like the distilled water. Measure the maximum differential pressure of the butanol solution with the concentration of 0.05,0.10,0.15,0.20,0.25,0.30,0.35mol/L. .(Note: every time the solution is changed, we should use the Pending liquid to wash the external case and the capillary tube) (5)Record the experimental temperature

4.Experimental procedures ⚫ (4)Drain the distilled after the maximum differential pressure has been measured.Wash the external case and the capillary tube once with butanol with the concentration of 0.002mol/L.Then add the solution and measure its maximum differential pressure just like the distilled water.Measure the maximum differential pressure of the butanol solution with the concentration of 0.05,0.10,0.15,0.20,0.25,0.30,0.35mol/L . ⚫ (Note: every time the solution is changed, we should use the Pending liquid to wash the external case and the capillary tube) (5) Record the experimental temperature