1.1 C Energy and Changes of State

GOALS

• Interpret observable changes in physical properties and temperature during changes of state ✅

• Convert between Celsius and Kelvin scales✅

• The kelvin (K) is the SI unit of temperature and has the same

  incremental value as the Celsius degree (°C) ✅

NOTE

• energy added during a change of state does NOT increase temperature

• goes into breaking inter-particle forces

TEMPERATURE CHANGE VS INPUT WHEN HEATING OBJECT AT CONSTANT PRESSURE

a-b: solid is heated, vibrational energy of particles increases so the temperature increases

b-c: melting point, vibrations are energetic enough for particles to move away from fixed positions and form a liquid. Energy added breaks interparticle forces, but does not raise kinetic energy so temperature remains constant

c-d: liquid is heated, particles gain kinetic energy and temperature increases

d-e: boiling point, sufficient energy to break all interparticle forces and form a gas.

• Requires more energy than melting

• Temperature remains constant

• Bubbles of gas visible throughout volume of liquid

e-f: gas is heated under pressure, kinetic energy of particles continues to rise, temperature also rises

KELVIN

• ^oC to Kelvin

  • Temperature (K) = Temperature (^oC) + 273.15

  • absolute zero (0 K) = -273.15 ^oC

    Q p 14 # 8,9