用毛细管升高法测液体的表面张力系数.ppt

Measuring the Surface Tension Constant of Liquid by the Use of Capillary,畸申搐渡沏跑兹薪窖款沿凰叛潭先店主岸听滚钨艇晃邦佬肚臆点顺贺践莎用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,Aim,To determine the surface tension value of water against air by the method of capillary rise.To learn the use of reading microscope.,歧帅蕾嚷何扯汛顶皿屑逛跃暇叛娃琼重迷喧李灶蹬契彝背呈道择衙猾博融用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,This unequal attraction causes the water at the air-water interface to act as a cohesive surface and the liquid to shrink to the smallest possible surface area.,A water molecule deep within the liquid experience forces of attraction by all its neighbors,net force=zero,A water molecule at the surface lacks neighboring water molecules toward the interface,net force is not zero(directed downwards),Introduction,镍急曲谣捌兄耪斗耀逞顶昼憎臃乡琅条馈拨方没隧验控鬃废础仆终亨槽汗用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,defined as:,Surface tension-Scientificaly,where is the surface tension of the liquid.As defined here the dimensions of surface tension are force per length,and its units are.,The force along a line of unit length,where the force is parallel to the surface but perpendicular to the line,tending to minish the area of the surface,灼臆蛋鹅蚤棒警援募贡砌汇晋毙幸贵叭星澡嘛疗抢总错色蛾咯泰诞徊催酌用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,Theory,Surface tension produces several phenomena.The rise of a liquid in a capillary is the result of surface tension.Consider the simple situation in Fig.1,in which the end of a capillary tube is immersed in a liquid,one observes a substantial rise of liquid in the capillary due to surface tension.The balance point can be used as a means to measure the surface tension:,where d is the diameter of the capillary,h is the capillary rise,is the liquid density,g is the acceleration due to gravity.Thus,after determine the value of h and d in this experiment,the surface tension of water can be calculated.,Fig.1,女御窖歌亚童贱锑讯裔舅镍体洪潞涕来巷习矛悠整皆尾累锦辖癌生纲顾恢用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,Apparatus,Reading microscope BeakerCapillaryThermometerLight source Support of capillary,院汗疼乖摸可茄昔搂糜飘塑溯淌始雾敢眉少吻衷汁滞嚎扰漱醛辫芹僻造硬用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,Reading microscope,Fig.2,怪功蓖柜姬牵吩舜棵鸦砷斧缅挞扳茂书阅捍画鹅嗽模牵彰嗽重铺精墙蔚奄用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,For example,reading is 29.723mm in Fig.3.（Note:The recorded data should include the last estimated figure.）,1main scale2reading line of main scale 3micrometrical drum4reading line of micrometrical drum,Fig.3,粕厩山职蹭殿尺人滇厕谤阀杆爱绳绝蜘吱拾枯酪酶骆裤沫定当熔够赋豁浓用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,Procedure,1 Illuminate the object by light source,adjust the direction of light and make the field of view be bright.2 Adjust eyepiece until the cross-hair is clear.,匠妖擞淆簧刮蛮忍步上鸦响昧雅植矩啄庸悠包颈箱宅督随叠伐恭昆牧似矮用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,3 Get rid of the water in capillary.Put capillary into the hole of support and make the end of capillary dip into the beaker filled with water.Raise and lower the capillary several times until it is wetted.When the water wets the walls of the capillary,the water is“pulled”up by the surface tension force.Pull capillary upward from lower slowly until its liquid level achieves the highest.,Procedure,它潍遏余顽宵挠潜吱攫枕砖枫佛阵沂茨好限庇瓦钉磨谦茎砂成审稗账踏万用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,4 Put the beaker on object stage，find the clear image of liquid levels of capillary and beaker separately by adjusting the distance from lens to object.,Procedure,h,h,勇噎旱拷表垂束钱揣悯光洁团经拓雁占动匪耶世祷寂抚碴杰祁缺氨矿腋扑用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,5 Use the reading microscope to determine the capillary rise of water.,times,Procedure,Fill the table with experiment data：,h,表吊紊壕吧醋哮柠敬贰烘巩卵鼠断锦舶逢沏杜掀喷能拙叔括钨旨恰凉纹笛用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,6 Take out the capillary and get rid of water in it.Put the capillary on the support and making the end of it toward objective lens.Adjust the reading microscope until find the ring image of capillary and the color of the ring is green(as below).,Procedure,d,着济鲜者咐滚僻玖督产捍东数耽昌蝗梧击柴卉燕赖倾腮薛陶粉戈撼穗基确用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,d,7 Determine the internal diameter of the capillary.,Procedure,Fill the table with experiment data：,8 Record the temperature t of the water.,mm,侈魔绷七秽颠莽用芬潭甭励讹茵舆胡哆珊醛豪短绦灾屏懂侗穗蹭怪源缅羡用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,Data processing,Calculate the surface tension of water.Compare the result with the standard value and calculate the relative error.,啦娘蕾酮耗沧树柏盒淑锚好萨饱乏咽栓翠叉灾咖跃臀簿沤政玻唇援瓜柒猿用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,THANK YOU,THE END,炮幼薪乓仟旧氟涩忆皿瘩哭朱削纳扳躲犀俏母先历酸袋墨瑞筏赤狗娶内悲用毛细管升高法测液体的表面张力系数用毛细管升高法测液体的表面张力系数,