Key Idea.
Section 1
It’s Still There!
It is easy to think that when sugar dissolves in tea, it is gone forever. But we know it is still there because we can taste it.
Dissolving is a physical change where matter breaks into invisible particles. The mass (weight) of the mixture proves this. If you weigh the water and the sugar separately, and then weigh the sweet water after mixing, the weight is the same. The matter didn't disappear; it just changed form.
Section 2
The Nanoscale View
To understand dissolving, we have to think small—really small. We call this the nanoscale.
At this scale, we can imagine the solid's particles vibrating and breaking loose. They swim away and mix with the liquid's particles. Even though we can't see this happening, understanding the behavior of these tiny particles explains why the macroscopic (visible) mixture looks clear.
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Section 1
It’s Still There!
It is easy to think that when sugar dissolves in tea, it is gone forever. But we know it is still there because we can taste it.
Dissolving is a physical change where matter breaks into invisible particles. The mass (weight) of the mixture proves this. If you weigh the water and the sugar separately, and then weigh the sweet water after mixing, the weight is the same. The matter didn't disappear; it just changed form.
Section 2
The Nanoscale View
To understand dissolving, we have to think small—really small. We call this the nanoscale.
At this scale, we can imagine the solid's particles vibrating and breaking loose. They swim away and mix with the liquid's particles. Even though we can't see this happening, understanding the behavior of these tiny particles explains why the macroscopic (visible) mixture looks clear.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter