1.4 The Particle Theory of Matter Homework Answers EXTRA

Particle Theory of Matter Homework Answers

1. Phase Changes

  • Ice to Liquid Transition:

    • Ice becomes a liquid when heat/energy is added.

    • Heating causes particles to gain energy and move faster.

    • Resulting effects include:

      • Weaker attractive forces between particles.

      • Greater space between particles.

2. Compressibility of Gases vs. Liquids

  • Ease of Compression:

    • Gases can be compressed more easily than liquids.

    • Reasons:

      • Gas particles are further apart due to higher energy and faster movement.

      • Weaker attractive forces in gases.

      • Liquids have closer particles, less energy, and stronger attractions.

    • Increased spacing in gases allows easy compression.

3. Density Comparison of Solid and Liquid Iron

  • Density of Solid vs. Liquid Iron:

    • Solid iron is denser than liquid iron due to particle arrangement.

    • Solid Iron:

      • Particles move slowly, are closely packed, and have strong attraction.

      • Higher number of particles per volume = greater density.

    • Liquid Iron:

      • Particles have more energy, are moving faster, and are spaced further apart.

      • Fewer particles in a volume = lesser density.

4. Energy and Phase Changes

  • Role of Heat:

    • Heat is a form of energy.

    • To turn a liquid into a solid:

      • Particles require lower energy to move more slowly and get closer together.

      • Removing energy source (heat) is necessary for solidification.

5. Effects of Heating on Jar Lids

  • Removing Lids:

    • Running a jar under hot water makes lid removal easier.

    • Reason:

      • Heat increases particles' energy, causing them to move faster and further apart.

      • Weaker attractive forces make the material softer and more liquid-like, facilitating easier lid movement.

6. Friction and Ice in Skating

  • Friction on Ice:

    • Skate friction generates heat.

    • Result:

      • Heat energizes water particles, allowing them to move faster and separate.

      • Weakened attractive forces create grooves on the ice surface.

7. Air Pressure in Tires

  • Understanding Air Pressure:

    • Pressure is the force applied to an area, with air pressure resulting from air particles hitting an object.

    • Air pressure increases in tires after a long trip due to:

      • Higher energy in air particles.

      • Weaker attractive forces, faster movement, and increased distance between particles.

      • More frequent collisions with tire particles raise internal pressure.

8. Concrete Expansion Gaps

  • Concrete Slabs:

    • Gaps between concrete slabs accommodate thermal expansion.

    • During temperature increase, concrete particles gain energy, move faster, and expand.

    • These spaces prevent cracking from the expansion of particles.

9. Freezing Point Depression

  • Substances like Salt and Antifreeze:

    • They lower water's freezing point, preventing ice formation at 0°C or lower.

    • Mechanism:

      • Salt/antifreeze particles infiltrate water molecules, disrupting solid formation.

      • Water particles still move slowly and closely together but are prevented from aggregating into ice due to salt interference.