specific heat

(noun)

The ratio of the amount of heat needed to raise the temperature of a unit mass of substance by a unit degree to the amount of heat needed to raise that of the same mass of water by the same amount.

Related Terms

Examples of specific heat in the following topics:

  • Specific Heat

    • This quantity is known as the specific heat capacity (or simply, the specific heat), which is the heat capacity per unit mass of a material .
    • The last two factors are encapsulated in the value of the specific heat.
    • The specific heat is the amount of heat necessary to change the temperature of 1.00 kg of mass by 1.00ºC.
    • In general, the specific heat also depends on the temperature.
    • Listed are the specific heats of various substances.

  • Specific Heat for an Ideal Gas at Constant Pressure and Volume

    • An ideal gas has different specific heat capacities under constant volume or constant pressure conditions.
    • Specific Heat for an Ideal Gas at Constant Pressure and Volume
    • The heat capacity at constant pressure of 1 J·K−1 ideal gas is:
    • The heat capacity ratio or adiabatic index is the ratio of the heat capacity at constant pressure to heat capacity at constant volume.
    • Potential energy stored in these internal degrees of freedom contributes to specific heat of the gas.

  • Solving Problems with Calorimetry

    • To do so, the heat is exchanged with a calibrated object (calorimeter).
    • The temperature change, along with the specific heat and mass of the solution, can then be used to calculate the amount of heat involved in either case.
    • Use these data to determine the specific heat of the metal.
    • Assuming perfect heat transfer, the heat given off by metal is the negative of the heat taken in by water, or:
    • Our experimental specific heat is closest to the value for copper (0.39 J/g °C), so we identify the metal as copper.

  • Calorimetry

    • Calorimetry requires that the material being heated have known thermal properties, i.e. specific heat capacities .
    • where δQ is the increment of heat gained by the sample, CV is the heat capacity at constant volume, cv is the specific heat at constant volume, and ΔT is the change in temperature.
    • Multiplying the temperature change by the mass and specific heat capacities of the substances gives a value for the energy given off or absorbed during the reaction:
    • It does not account for the heat loss through the container or the heat capacity of the thermometer and container itself.
    • where Cp is the specific heat at constant pressure, ΔH is the enthalpy of the solution, ΔT is the change in temperature, W is the mass of the solute, and M is the molecular mass of the solute.

  • Convection

    • We are given that ΔT is 10.0ºC, but we must still find values for the mass of air and its specific heat before we can calculate Q.
    • The specific heat of air is a weighted average of the specific heats of nitrogen and oxygen, which is c=cp≅1000 J/kg⋅C (note that the specific heat at constant pressure must be used for this process).
    • Instead heat diffusion in solids is called heat conduction, which we've just reviewed.
    • Heat is removed from the ocean when water evaporates.
    • If the water vapor condenses in liquid droplets as clouds form, heat is released in the atmosphere (this heat release is latent heat)  .

  • Constant Pressure

    • (Eq. 2), where W is work done by the system, U is internal energy, and Q is heat.
    • The law says that the heat transferred to the system does work but also changes the internal energy of the system.
    • Specific heat at constant pressure is defined by the following equation:

  • Latent Heat

    • Previously, we have discussed temperature change due to heat transfer.
    • where the latent heat of fusion, Lf, and latent heat of vaporization, Lv, are material constants that are determined experimentally.
    • Lf and Lv are collectively called latent heat coefficients.
    • Once all the ice has melted, the temperature of the liquid water rises, absorbing heat at a new constant rate of 1.00 cal/g⋅C (remember that specific heats are dependent on phase).
    • Heat from the air transfers to the ice causing it to melt.

  • Heat as Energy Transfer

    • Heat is the spontaneous transfer of energy due to a temperature difference.
    • This observation leads to the following definition of heat: Heat is the spontaneous transfer of energy due to a temperature difference .
    • Heat is often confused with temperature.
    • Heat is a form of energy, whereas temperature is not.
    • The calorie (cal) is a common unit of energy, defined as the energy needed to change the temperature of 1.00 g of water by 1.00ºC —specifically, between 14.5ºC and 15.5ºC, since there is a slight temperature dependence.

  • Heat Pumps and Refrigerators

    • A heat pump is a device that transfers heat energy from a heat source to a heat sink against a temperature gradient.
    • Heat pumps, air conditioners, and refrigerators utilize heat transfer from cold to hot.
    • Actually, a heat pump can be used both to heat and cool a space.
    • As with heat pumps, work input is required for heat transfer from cold to hot.
    • What is considered the benefit in a heat pump is considered waste heat in a refrigerator.

  • Infrared Waves

    • This range is sometimes called the fingerprint region, since the mid-infrared absorption spectrum of a compound is very specific for that compound.
    • Infrared radiation is popularly known as "heat radiation," but light and electromagnetic waves of any frequency will heat surfaces that absorb them.
    • Heat is energy in transient form that flows due to temperature difference.
    • Unlike heat transmitted by thermal conduction or thermal convection, radiation can propagate through a vacuum.
    • Applications of IR waves extend to heating, communication, meteorology, spectroscopy, astronomy, biological and medical science, and even the analysis of works of art.