Answers – States of matter

Answer: The three main states of matter are:

• Solid: Examples include ice, iron, diamond, wood
• Liquid: Examples include water, oil, mercury, blood
• Gas: Examples include oxygen, carbon dioxide, steam, nitrogen

Answer:

• Solids: Particles are packed closely together in a regular pattern. They can only vibrate about fixed positions and cannot move from place to place.
• Liquids: Particles are close together but arranged randomly. They can move past each other and throughout the liquid.
• Gases: Particles are very far apart and arranged randomly. They move quickly in all directions with no restrictions except the walls of the container.

Answer: Gases can be easily compressed while solids cannot because of the different particle arrangements. In gases, the particles are very far apart with mostly empty space between them. When pressure is applied, these particles can be pushed closer together, reducing the volume. In solids, the particles are already tightly packed with minimal space between them. Since particles cannot occupy the same space, there is almost no room for further compression.

Answer:

• Melting: The change of state from solid to liquid when heat energy is added (e.g., ice to water)
• Freezing: The change of state from liquid to solid when heat energy is removed (e.g., water to ice)
• Evaporation: The change of state from liquid to gas when heat energy is added (e.g., water to steam)
• Condensation: The change of state from gas to liquid when heat energy is removed (e.g., steam to water)

Answer: During a change of state, the temperature of a substance remains constant even though energy is being added or removed. This is because the energy is used to change the arrangement of the particles rather than increase their kinetic energy. For example, when ice is melting at 0°C, any added energy is used to break the bonds between particles in the solid, allowing them to move more freely as a liquid, rather than making the particles move faster (which would increase the temperature).

Answer: When ice at -10°C is heated:

1. From -10°C to 0°C: The particles of ice vibrate more vigorously as they gain energy, but remain in fixed positions. The temperature increases.
2. At 0°C (melting point): The particles gain enough energy to partially overcome the strong forces holding them in place. The structure begins to break down as ice melts to water. Temperature remains constant at 0°C during melting.
3. From 0°C to 100°C: The particles in liquid water move more freely and faster as temperature increases. They are still close together but can slide past each other.
4. At 100°C (boiling point): The particles gain enough energy to completely overcome the forces between them and become free-moving gas particles. Temperature remains constant at 100°C during boiling.
5. Above 100°C: The steam (water vapor) particles move even faster as temperature continues to increase to 110°C.

Answer:

Answer: Diffusion occurs more quickly in gases than in liquids because:

• Gas particles are much further apart, allowing easier movement through the spaces
• Gas particles move much faster than liquid particles at the same temperature
• There are weaker forces of attraction between gas particles, so they can move more freely
• Liquid particles are held closer together by stronger intermolecular forces, restricting their movement

Answer: When the temperature of a substance increases, the average kinetic energy of its particles increases. This affects particle movement in different ways depending on the state:

• In solids: Particles vibrate more vigorously about their fixed positions
• In liquids: Particles move more quickly and have more energy to overcome the forces between them, allowing them to move more freely
• In gases: Particles move even faster in all directions, colliding more energetically with each other and the container walls

Answer: When the perfume bottle is opened at the front of the classroom, the liquid perfume begins to evaporate. The perfume particles enter the gaseous state and mix with the air particles. Due to their kinetic energy, these gas particles move randomly in all directions at high speeds. They collide with air particles and gradually spread throughout the room through diffusion, moving from areas of higher concentration (near the bottle) to areas of lower concentration (the back of the room). Once the perfume particles reach the student at the back, they interact with the olfactory receptors in the student’s nose, allowing them to smell the perfume. This process demonstrates diffusion in gases, which occurs because gas particles move freely and have large spaces between them.

Answer: Diagrams showing particle arrangements:

1. Solid: Particles are arranged in a regular pattern (often shown as a lattice), very close together. Each particle vibrates in a fixed position but does not move from place to place.
2. Liquid: Particles are close together but arranged randomly. They can move past each other and throughout the liquid, but are still close enough to maintain contact.
3. Gas: Particles are very far apart and arranged randomly. They move freely in all directions at high speeds with large spaces between them.

Note: In proper diagrams, solid particles would be shown in ordered rows, liquid particles would be clustered together but in random positions, and gas particles would be scattered widely with lots of empty space.

Answer: Water has a fixed volume but takes the shape of its container because of the arrangement and behavior of its particles. In liquid water, the particles:

• Are close together but not in fixed positions (unlike in solids)
• Have moderate forces of attraction between them, keeping them at a fairly constant distance from each other (maintaining the fixed volume)
• Can move past one another and flow (allowing the liquid to change shape)
• Are not fixed in place, so they can rearrange themselves to fill the bottom of any container they are placed in
• Have enough energy to overcome some of the forces between them, but not enough to separate completely as in a gas

Answer: Ice floating on water tells us that solid water (ice) is less dense than liquid water. This is unusual because for most substances, the solid state is denser than the liquid state. This unusual property occurs because water molecules in ice form a crystalline structure with hydrogen bonds that hold the molecules further apart than in liquid water. The hydrogen bonds create a hexagonal lattice with open spaces, making ice less dense. When ice melts, some of these hydrogen bonds break, allowing the molecules to pack closer together, increasing the density. This unusual property is important for life on Earth, as it allows ice to float on lakes and oceans, insulating the water below and allowing aquatic life to survive during freezing conditions.

Answer:

1. Freezing (liquid to solid): Energy is released (exothermic process)
2. Evaporation (liquid to gas): Energy is absorbed (endothermic process)
3. Condensation (gas to liquid): Energy is released (exothermic process)
4. Melting (solid to liquid): Energy is absorbed (endothermic process)

In general, processes that involve increasing disorder (melting, evaporation) require energy to be added, while processes that involve increasing order (freezing, condensation) release energy.