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1、水沸腾前后气泡变化为什么不同呢?DIV.MyFav_1288926874927 P.MsoNormalTEXT-JUSTIFY: inter-ideograph; FONT-SIZE: 10.5pt; MARGIN: 0cm 0cm 0pt; FONT-FAMILY: Times New Roman; TEXT-ALIGN: justifyDIV.MyFav_1288926874927 LI.MsoNormalTEXT-JUSTIFY: inter-ideograph; FONT-SIZE: 10.5pt; MARGIN: 0cm 0cm 0pt; FONT-FAMILY: Times New
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7、-GRID-MODE: char; FONT-FAMILY: Times New RomanDIV.MyFav_1288926874927 DIV.Section1page: Section1在做水的沸腾实验时,我们可以很明显地观察到,水在沸腾前气泡在上升过程中体积变得越来越小(如图1),而在沸腾后气泡在上升过程中体积反而变得越来越大(如图2)。为什么水沸腾前后气泡的变化会相反呢?原来,沸腾前加热过程中,由于水是热的不良导体,致使下部分的水温较高,上部分的水温较低,气体受热胀冷缩影响明显,因此底部气泡在上升过程中逐渐缩小;而沸腾后容器内各部分水的温度都相同,水汽化后的蒸气形成气泡,气泡在上升过程中受压强的影响,越往上水的压强越小,气泡就会逐渐变大。