14 Temperature (A2)

14.1 Thermal Equilibrium

  • Thermal energy is transferred from a region of higher temperature to a region of lower temperature until both regions reach thermal equilibrium.

  • Regions of equal temperature are in thermal equilibrium, meaning that there is no net heat transfer between them.

14.2 Temperature Scales

  • A physical property that varies with temperature can be used for the measurement of temperature. Examples of such properties include the density of a liquid, volume of a gas at constant pressure, resistance of a metal, and e.m.f. of a thermocouple.

  • The scale of thermodynamic temperature (kelvin) does not depend on the property of any particular substance and is based on the behavior of ideal gases.

  • Temperatures can be converted between kelvin and degrees Celsius using the formula T/K = θ/°C + 273.15.

  • The lowest possible temperature is zero kelvin on the thermodynamic temperature scale, also known as absolute zero. At this temperature, the particles of matter have zero kinetic energy and cannot transfer any heat.

14.3 Specific Heat Capacity and Specific Latent Heat

Specific Heat Capacity :

amount of heat energy required to raise the temperature of 1 kilogram of a substance by 1 Kelvin

  • The formula for specific heat capacity is Q = mc∆T, where Q is the heat energy transferred, m is the mass of the substance, c is its specific heat capacity, and ∆T is the change in temperature.

Specific Latent Heat:

amount of heat energy required to change the state of 1 kilogram of a substance without changing its temperature

  • Specific latent heat of fusion is the amount of heat energy required to change 1 kilogram of a solid into a liquid at its melting point, and specific latent heat of vaporization is the amount of heat energy required to change 1 kilogram of a liquid into a gas at its boiling point.