Thermal Expansion and Specific Heat Capacity

Thermal Expansion

• Solids, liquids, and gases expand when heated at constant pressure.
• Gases expand more than liquids, which expand more than solids.
• This is due to the greater separation of particles in gases compared to liquids and solids.
• Expansion applies to real-world situations, like expansion joints in bridges and gaps in railway tracks.
• It's also a principle used in bimetallic strips of thermostats.
• Particles move faster and spread further apart when heated.

Specific Heat Capacity

• A temperature rise in an object increases its internal energy.
• Higher temperatures correlate with increased average kinetic energy of particles.
• Specific heat capacity (c) is the energy needed to raise the temperature of 1 kg of a substance by 1°C.
• The formula for specific heat capacity is: c = ΔE / (m * Δθ), where:
  • ΔE = change in energy
  • m = mass
  • Δθ = change in temperature.
• Measuring specific heat capacity involves using a known heat source and measuring the temperature change in a solid or liquid.

Melting, Boiling, and Evaporation

• During melting and boiling, energy input causes a state change (solid to liquid or liquid to gas) without a change in temperature. Latent heat is involved.
• Water melts at 0°C and boils at 100°C (standard pressure).
• Condensation and solidification involve energy removal; particles slow down and form bonds (liquid to solid or gas to liquid).
• Evaporation is the escape of high-energy particles from a liquid's surface. This doesn't require the liquid to reach its boiling point
• Evaporation cools the remaining liquid, because the fast-moving particles leave, reducing the average energy of the remaining particles.
• Boiling occurs throughout the liquid at a fixed temperature, whereas evaporation occurs only at the surface at any temperature.
• Evaporation is affected by temperature, surface area, and air movement (higher temperature, more surface area, and air movement lead to faster evaporation).
• Evaporation absorbs heat from the surrounding environment. (e.g., sweating).

This quiz covers the fundamental concepts of thermal expansion and specific heat capacity. Explore how different states of matter respond to temperature changes and the principles governing energy transfer. Gain insights into real-world applications such as bridges and thermostats.