In the lab, we put a small amount of potassium permanganate into a beaker of water. Look at the photos to see what happens. In the top row, the water in the beaker is cold and in the bottom row, the water is hot.
If we look very closely, we can see that the particles behave in very different ways depending on the temperature of the water. It looks like the water molecules in the beaker with hot water are moving, which makes the potassium permanganate dissolve faster.
This phenomenon is the basis for the Kinetic Particle Theory (also called the Kinetic Theory of Matter) which states:
Matter is composed of particles, invisible to the naked eye, that are in some way attracted to each other (have cohesive force).
These particles are in constant motion. As the temperature rises, the speed of the particles increases.
The state of matter depends on how close together (or aggregated) the particles are. So we talk about the state of aggregation of matter.
Activity 3
Fill in the blanks to explain why solids have a fixed shape and a constant volume.
Activity 4
Why can we compress gas contained in a syringe but we can’t do the same with a syringe filled with water? Complete the explanation applying the Kinetic Particle Theory.
Activity 5
At a microscopic level, why is the density of solids only slightly greater than the density of liquids but the density of liquids is considerably greater than the density of gases? Complete the explanation.
