Question
Why are some substances found in the solid state, some in the liquid state and others in the gaseous state?
✓
Answer
It all depends upon the amount of kinetic energy available with the constituent particles which determines their speed and the attractive forces existing between them.
1) If the constituent particles have sufficiently more kinetic energy, and they move so fast that they are not able to remain close to each other. Then the substance is in gaseous state.
2) If they are moving slowly enough then the force between the constituent particles have a chance to pull them together and the substance then exists in the form of a liquid.
3) If the constituent particles are moving so slowly that the forces of attraction hold them rigidly together, then substance exist in the form of a solid.
The important fact to keep in mind is that, 'the higher the temperature, the faster the constituent particles move'. Due to this reason, solids melt as the temperature increases and vapourises at yet higher temperatures. The exact temperature at which a change takes place depends on the strength of the force between the molecules.
1) If the constituent particles have sufficiently more kinetic energy, and they move so fast that they are not able to remain close to each other. Then the substance is in gaseous state.
2) If they are moving slowly enough then the force between the constituent particles have a chance to pull them together and the substance then exists in the form of a liquid.
3) If the constituent particles are moving so slowly that the forces of attraction hold them rigidly together, then substance exist in the form of a solid.
The important fact to keep in mind is that, 'the higher the temperature, the faster the constituent particles move'. Due to this reason, solids melt as the temperature increases and vapourises at yet higher temperatures. The exact temperature at which a change takes place depends on the strength of the force between the molecules.
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