什么是表面張力?
來(lai)源:本(ben)站原創 瀏覽(lan) 1768 次 發布時間(jian):2018-03-27
Q: 什么是表面張力?
A:液體(ti),原來液體(ti)與(yu)氣(qi)體(ti)相接(jie)觸(chu)時(shi),會(hui)形(xing)(xing)成一(yi)個表(biao)(biao)面(mian)(mian)(mian)(mian)層(ceng),在這個表(biao)(biao)面(mian)(mian)(mian)(mian)層(ceng)內(nei)存在著(zhu)的(de)(de)相互(hu)吸引力(li)就是表(biao)(biao)面(mian)(mian)(mian)(mian)張(zhang)力(li),它能(neng)使液面(mian)(mian)(mian)(mian)自動收(shou)縮。表(biao)(biao)面(mian)(mian)(mian)(mian)張(zhang)力(li)是由液體(ti)分子間很大的(de)(de)內(nei)聚力(li)引起的(de)(de).不(bu)(bu)(bu)光(guang)液體(ti)與(yu)氣(qi)體(ti)之(zhi)間的(de)(de)表(biao)(biao)面(mian)(mian)(mian)(mian)層(ceng),液體(ti)與(yu)固(gu)體(ti)器(qi)壁(bi)之(zhi)間也(ye)存在著(zhu)“表(biao)(biao)面(mian)(mian)(mian)(mian)層(ceng)”,這一(yi)液體(ti)薄層(ceng)通常叫做(zuo)附著(zhu)層(ceng),它也(ye)一(yi)樣存在著(zhu)表(biao)(biao)面(mian)(mian)(mian)(mian)張(zhang)力(li)。這一(yi)表(biao)(biao)面(mian)(mian)(mian)(mian)張(zhang)力(li)決定了液體(ti)和(he)固(gu)體(ti)接(jie)觸(chu)時(shi),會(hui)出現(xian)(xian)兩種現(xian)(xian)象(xiang):不(bu)(bu)(bu)浸潤(run)(run)(run)(run)和(he)浸潤(run)(run)(run)(run)現(xian)(xian)象(xiang)。水(shui)銀(yin)(yin)(yin)掉到玻(bo)(bo)(bo)璃(li)上(shang)(shang),是呈現(xian)(xian)出球形(xing)(xing),也(ye)就是說,水(shui)銀(yin)(yin)(yin)與(yu)玻(bo)(bo)(bo)璃(li)的(de)(de)接(jie)觸(chu)面(mian)(mian)(mian)(mian)具有收(shou)縮趨勢,這種現(xian)(xian)象(xiang)為不(bu)(bu)(bu)浸潤(run)(run)(run)(run)。而(er)水(shui)滴(di)(di)掉到玻(bo)(bo)(bo)璃(li)上(shang)(shang),是慢慢地(di)沿(yan)玻(bo)(bo)(bo)璃(li)散(san)(san)開,接(jie)觸(chu)面(mian)(mian)(mian)(mian)有擴大趨勢,這種現(xian)(xian)象(xiang)為浸潤(run)(run)(run)(run)。水(shui)銀(yin)(yin)(yin)雖然不(bu)(bu)(bu)能(neng)浸潤(run)(run)(run)(run)玻(bo)(bo)(bo)璃(li),但是用稀(xi)硫酸把鋅板(ban)擦干凈后,再(zai)在板(ban)上(shang)(shang)滴(di)(di)上(shang)(shang)水(shui)銀(yin)(yin)(yin),我們將會(hui)看到,水(shui)銀(yin)(yin)(yin)慢慢地(di)沿(yan)鋅板(ban)散(san)(san)開,而(er)不(bu)(bu)(bu)再(zai)呈球形(xing)(xing)。所以說,同一(yi)種液體(ti)能(neng)夠浸潤(run)(run)(run)(run)某(mou)些固(gu)體(ti),而(er)不(bu)(bu)(bu)能(neng)浸潤(run)(run)(run)(run)另一(yi)些固(gu)體(ti)。水(shui)銀(yin)(yin)(yin)能(neng)浸潤(run)(run)(run)(run)鋅,而(er)不(bu)(bu)(bu)能(neng)浸潤(run)(run)(run)(run)玻(bo)(bo)(bo)璃(li);水(shui)能(neng)浸潤(run)(run)(run)(run)玻(bo)(bo)(bo)璃(li),而(er)不(bu)(bu)(bu)能(neng)浸潤(run)(run)(run)(run)石(shi)蠟。