It can be seen as a spreading-out of particles resulting in their even distribution. Placing a drop of food coloring in water provides a visual representation of this process — the color slowly spreads out through the water.
If matter were not made of particles, then we would simply see a clump of color, since there would be no smaller units that could move about and mix in with the water. Interactive: Diffusion of a Drop : Click in the model to add a drop of dye. Watch how the molecules move through the water. Trace an individual molecule to see how it moves through the liquid. Privacy Policy.
Skip to main content. Liquids and Solids. Search for:. Kinetic Molecular Theory of Matter The Kinetic Molecular Theory of Matter The kinetic molecular theory of matter explains how matter can change among the phases of solid, liquid, and gas. Learning Objectives Describe the kinetic molecular theory of matter. The kinetic theory of matter is also illustrated by the process of diffusion. Diffusion is the movement of particles from a high concentration to a low concentration. It can be seen as a spreading-out of particles resulting in their even distribution.
Placing a drop of food coloring in water provides a visual representation of this process — the color slowly spreads out through the water. If matter were not made of particles, then we would simply see a clump of color, since there would be no smaller units that could move about and mix in with the water.
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:.
Skip to main content. Liquids and Solids. Search for:. Encourage students to identify these and talk through possible explanations. Some prompts:. If needed, raise issues such as these, which will open up discussion, but it is better if the students themselves come up with some.
Note that many of the issues are to do with gases — it is their properties that we most need a particulate model to explain. To reinforce the notion of elastic collisions, ask what would happen if collisions between gas particles were not elastic. What practical consequences would there be for people? This can be introduced by dropping different types of balls such as a soccer ball, a table tennis ball and a bouncy ball from toy shops and explaining that a bouncy ball behaves more like gas particles.
Using activities like POE Predict-Observe-Explain can help students think about and then question their existing ideas. The following activity will help students consider their ideas about the movement of particles. Set up two pairs of flasks each connected by a valve see diagrams below. Both pairs have brown nitrogen dioxide in the left hand side flask. The first pair also has air in the right hand side flask. Students are asked to predict what will happen when the valve between the two flasks is opened.
The brown colour will spread very slowly from one flask to the other because the particles have frequent collisions with the air particles. The second pair of flasks has brown gas in the left hand side flask but the right hand side flask is completely evacuated. Students are asked again to predict what happens when the valve is opened.
The very fast speed of the molecules means that they fill the evacuated flask very quickly. Diffusion experiments can reinforce the idea of movement of particles. These can also be used as POEs.
Brownian motion can also be observed using stereo microscopes when sulphur powder or camphor is sprinkled on the surface of water or ethanol. A cotton wool piece soaked in ammonia is placed at one end of a long glass tube with another soaked in hydrochloric acid HCl placed at the other end. Eventually a white ring will form where the two gases meet. The two gases are at the same temperature and thus the particles have the same kinetic energy; the ring forms closer to the source of heavier and thus slower moving HCl.
This is predicted by a comparison of the relative molecular masses. Including a strip of universal indicator paper in the tube allows the gas diffusion to be tracked.
Students need to be given the opportunity to use the scientific conceptions about particle theory in other settings. Our website uses a free tool to translate into other languages.
0コメント