What you need:
·Sugar
·Cold water in a clear glass
·Hot water in a clear glass
·Spoon for stirring (搅拌)
What you do:
·Make sure the glasses have the same amount of water.
·Put an amount of sugar into the cold water and stir it with the spoon until the sugar disappears. Repeat this process ( remembering to count the amount of sugar you put into the water) until the sugar stops dissolving (溶解). At this point, the sugar starts to gather on the bottom of the glass rather than dissolving.
·Write down how much sugar you could dissolve in the cold water.
·Repeat the same process in the hot water, and then compare the number of sugar dissolved in each glass. Which dissolved more? What's happening?
What's happening?
The cold water isn't able to dissolve as much sugar as the hot water. Sugar dissolves in the hot water three times as fast as in the cold water. But why? Another name for the liquids inside the glasses is a "solution". When this solution can no longer dissolve sugar, it becomes a "saturated (饱和的) solution". This means that sugar starts forming on the bottom of the glass.
The reason why the hot water dissolves more is that it has faster moving molecules(分子) which are spread further apart than the molecules in the cold water. With bigger gaps between the molecules in the hot water, more sugar molecules can fit in between them.
