heat

Chemistry

(noun)

The energy transferred from one system to another by thermal interaction.

Related Terms

  • work
  • thermochemistry
Physics

(noun)

energy transferred from one body to another by thermal interactions

Related Terms

  • internal energy
  • law of conservation of energy
  • thermodynamics

Examples of heat in the following topics:

  • Specific Heat

    • The specific heat is an intensive property that describes how much heat must be added to a particular substance to raise its temperature.
    • The heat capacity is an extensive property that describes how much heat energy it takes to raise the temperature of a given system.
    • 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 specific heat is the amount of heat necessary to change the temperature of 1.00 kg of mass by 1.00ºC.
    • Note that the total heat capacity C is simply the product of the specific heat capacity c and the mass of the substance m, i.e.,
  • Water’s High Heat Capacity

    • The high heat capacity of water has many uses.
    • The heat is quickly transferred to a pool of water to cool the reactor.
    • The capability for a molecule to absorb heat energy is called heat capacity, which can be calculated by the equation shown in the figure .
    • Water has the highest specific heat capacity of any liquid.
    • Specific heat is defined as the amount of heat one gram of a substance must absorb or lose to change its temperature by one degree Celsius.
  • Specific Heat and Heat Capacity

    • the molar heat capacity, which is the heat capacity per mole of a pure substance.
    • the specific heat capacity, often simply called specific heat, which is the heat capacity per unit mass of a pure substance.
    • Now we can plug our values into the formula that relates heat and heat capacity:
    • Latent heat of melting describes tœhe amount of heat required to melt a solid.
    • The above simulation demonstrates the specific heat and the latent heat.
  • 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.
  • The Heat-Shock Response

    • Heat shock response is a cell's response to intense heat, including up-regulation of heat shock proteins.
    • Heat shock response is the cellular response to heat shock includes the transcriptional up-regulation of genes encoding heat shock proteins (HSPs) as part of the cell's internal repair mechanism .
    • HSPs are also called 'stress-proteins' and respond to heat, cold and oxygen deprivation by activating several cascade pathways.
    • The up-regulation of HSPs during heat shock is generally controlled by a single transcription factor; in eukaryotes this regulation is performed by heat shock factor (HSF), while σ32 is the heat shock sigma factor in Escherichia coli.
    • Heat shock protein come in many sizes.
  • Overview of Heat

    • Energy can exist in many forms and heat is one of the most intriguing.
    • This module defines and explores heat transfer, its effects, and the methods by which heat is transferred.
    • Maxwell outlined four stipulations for the definition of heat:
    • After defining and quantifying heat transfer and its effects on physical systems, we will discuss the methods by which heat is transferred.
    • So many processes involve heat transfer, so that it is hard to imagine a situation where no heat transfer occurs.
  • Heat and Work

    • Heat transfer by convection occurs through a medium.
    • Lastly, heat can also be transferred by radiation; a hot object can convey heat to anything in its surroundings via electromagnetic radiation.
    • Like heat, the unit measurement for work is joules (J).
    • Heat and work are related.
    • Work can be completely converted into heat, but the reverse is not true: heat energy cannot be wholly transformed into work energy.
  • Heat Engines

    • In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work.
    • In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work .
    • We define the efficiency of a heat engine (Eff) to be its net work output W divided by heat transfer to the engine Qh:
    • (b) A heat engine, represented here by a circle, uses part of the heat transfer to do work.
    • Qh is the heat transfer out of the hot reservoir, W is the work output, and Qc is the heat transfer into the cold reservoir.
  • 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.
    • We use the phrase "heat transfer" to emphasize its nature.
  • Heating Curve for Water

    • Water transitions from ice to liquid to water vapor as heat is added to it.
    • A heating curve shows how the temperature changes as a substance is heated up at a constant rate.
    • A constant rate of heating is assumed, so that one can also think of the x-axis as the amount of time that goes by as a substance is heated.
    • Instead, use the heat of fusion ($\Delta H_{fusion}$ ) to calculate how much heat was involved in that process: $q=m\cdot \Delta H_{fusion}$, where m is the mass of the sample of water.
    • Use the heat of vaporization ($\Delta H_{vap}$ ) to calculate how much heat was absorbed in this process: $q=m\cdot C_{H_2O(g)}\cdot \Delta T$, where m is the mass of the sample of water.
Subjects
  • Accounting
  • Algebra
  • Art History
  • Biology
  • Business
  • Calculus
  • Chemistry
  • Communications
  • Economics
  • Finance
  • Management
  • Marketing
  • Microbiology
  • Physics
  • Physiology
  • Political Science
  • Psychology
  • Sociology
  • Statistics
  • U.S. History
  • World History
  • Writing

Except where noted, content and user contributions on this site are licensed under CC BY-SA 4.0 with attribution required.