2.1.1 States of matter (3)
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1.
The pressure inside a container is directly related to the number of particles and their kinetic energy. Explain how the average kinetic energy of particles in a gas is affected by temperature. Also, explain how this relationship relates to the concept of diffusion.
Relationship between Temperature and Kinetic Energy:
The average kinetic energy of the particles in a gas is directly proportional to the absolute temperature of the gas. This means that as the temperature of the gas increases, the average speed of the gas particles increases, and therefore their average kinetic energy increases. This is because temperature is a measure of the average energy of the particles in a substance.
Relationship to Diffusion:
Diffusion is the movement of particles from a region of high concentration to a region of low concentration. The rate of diffusion is directly related to the average kinetic energy of the particles. Higher kinetic energy means the particles move faster and collide more frequently. These more frequent and faster collisions lead to a quicker spread of particles, resulting in a faster rate of diffusion. Therefore, warmer gases diffuse faster than colder gases. The kinetic energy allows the particles to overcome intermolecular forces and move more readily.
2.
A student is investigating the changes of state of water. They observe ice melting and then the water boiling.
(a) Define the terms melting and boiling in terms of the changes in state of water.
(b) Describe the changes in the arrangement and movement of the water molecules during melting and boiling.
(a) Melting is the change of state from a solid (ice) to a liquid (water). Boiling is the change of state from a liquid (water) to a gas (steam).
(b)
- Melting: In a solid, water molecules are arranged in a fixed, ordered structure with limited movement. During melting, the molecules gain energy, allowing them to overcome the forces holding them in place. They become more disordered and can move more freely, transitioning into a liquid state.
- Boiling: In a liquid, water molecules are still relatively close but can move past each other. During boiling, the molecules gain sufficient energy to completely overcome the intermolecular forces. They escape from the liquid phase and become a gas, moving rapidly and randomly.
3.
A student is asked to describe the differences between solids, liquids and gases. State three distinguishing properties of each state of matter.
Solids:
- Fixed shape and volume.
- High density.
- Particles are closely packed in a regular arrangement.
Liquids:
- Variable volume, but fixed shape (takes the shape of the container).
- High density (generally, but less than solids).
- Particles are close together but can move past each other.
Gases:
- Variable volume and shape (fills the entire container).
- Low density.
- Particles are widely spaced and move randomly.