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1．简答题例1 如图1所示,在室温下的饱和食盐溶液中放入了一个塑料小球．请根据学过的理化知识,回答下列问题: (1)现加入少量食盐晶体,充分搅拌和静置后(在温度不变的情况下进行), 小球在液面沉浮情况有何变化,并简述原因; (2)若要在不用外力的情况下,使小球略上浮,你准备采取的具体方法是什么? 解析:(1)因为将食盐放入它的饱和溶液中,在温度不变的情况下食盐不会再溶解,溶液的密度不会改变,小球排开水的体积不变．所以小球在液面沉浮情况不变． (2)在不用外力的情况下要使小球略上浮,必须使溶液的密度增大,才能使小球浸入水
1. Short answer example 1 As shown in Figure 1, a plastic pellet was placed in a room temperature saturated salt solution. Please answer the following questions according to the physics and chemistry knowledge you have learned: (1) Now add a small amount of salt crystals, fully stir and rest (after the temperature is kept constant), and what happens to the ball’s ups and downs in the liquid surface, and Briefly describe the reasons; (2) If you want to make the ball slightly floating without external force, what is the specific method you are going to take? Resolution: (1) Because salt is put into its saturated solution, the temperature is not In case of change, the salt will not dissolve again, the density of the solution will not change, and the volume of water in the ball will not change. Therefore, the ball does not change in the liquid surface. (2) To make the ball slightly floating without external force, it is necessary to increase the density of the solution so that the ball can be immersed in water.