The molar and specific heat capacities are dependent upon the internal degrees of freedom of the system and not on any external properties, such as volume and number of molecules.

The infinitesimal expression for heat, , forms an inexact differential for processes involving work.

The hypothesis that heat is a form of motion was proposed initially in the twelfth century.

State functions return to their initial values upon completion of each cycle in cyclic processes such as that of a heat engine.

Radiation is the only form of heat transfer that can occur in the absence of any form of medium and as such is the only means of heat transfer through a vacuum.

Temperature is used as a measure of the internal energy or enthalpy, that is the level of elementary motion giving rise to heat transfer.

The specific heats of monatomic gases (for example, helium) are nearly constant with temperature.

In 1761, Scottish chemist Joseph Black discovered that ice absorbs heat without changing temperature when melting.

The changes in enthalpy and internal energy can be related to the heat capacity of a gas at constant pressure and volume respectively.

The amount of heat transfer during a phase change is known as latent heat and depends primarily on the substance and its state.

Heat is the transfer of energy caused by temperature difference.

The first recorded to have put forward a theory on heat was the Greek philosopher Heraclitus, who lived around 500 B.C.E.

The term heat is used to describe the flow of energy.

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Heat is transferred between objects by radiation, conduction, or convection.

In 1797, cannon manufacturer Sir Benjamin Thompson, Count Rumford, demonstrated through the use of friction it was possible to convert work to heat.

At temperatures well below the characteristic Debye temperature of a solid lattice, its specific heat will be proportional to the cube of absolute temperature.

Between 1759 and 1763, he developed the theory of "latent heat," on which his scientific fame chiefly rests, and also showed that different substances have different specific heats.

Heat flux is defined as rate of heat transfer per unit cross-sectional area, and is denoted q, resulting in units of watts per meter squared, though slightly different notation conventions can be used.

Radiation is the only form of heat transfer that can occur in the absence of any form of medium and as such is the only means of heat transfer through a vacuum.

Specific heat of a substance is the amount of energy that has to be transferred to or from one unit of mass or mole of a substance to change its temperature by one degree.

Several theories on the nature of heat were developed.

Conduction is the most significant means of heat transfer in a solid.

The temperature and state of a substance subject to heat transfer are determined by latent heat and heat capacity.

The ability to use heat transfer to generate work allowed for the invention and development of the steam engine by such persons as Thomas Newcomen and James Watt.

The transfer of heat from an object, to another object with an equal or higher temperature, however, can happen only with the aid of a heat pump.

Heat spontaneously flows from an object with a high temperature to an object with a lower temperature.

Specific heat is a property, which means that it depends on the substance under consideration and its state as specified by its properties.

Heat capacity is an extensive quantity and as such is dependent on the number of molecules in the system.

On a microscopic scale, conduction occurs as hot, rapidly moving or vibrating atoms and molecules interact with neighboring atoms and molecules, transferring some of their energy (heat) to these neighboring atoms.

The boiling point of water, at sea level and normal atmospheric pressure and temperature, will always be at nearly 100°C, no matter how much heat is added.

The conventional sign is that when a body releases heat into its surroundings, Q < 0 (-); when a body absorbs heat from its surroundings, Q > 0 (+).

According to Carnot, this principle applies to any machine set in motion by heat.

Heat transfer is a path function (process quantity), as opposed to a point function (state quantity).

The extra heat changes the phase of the water from liquid into water vapor.

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The total amount of energy moved through heat transfer is conventionally abbreviated as Q.

which means that the energy of the system can change either via work or via heat.

The work of Joule and Mayer demonstrated that heat and work were interchangeable, and led to the statement of the principle of the conservation of energy by Hermann von Helmholtz in 1847.

Heat and work are the only two mechanisms by which energy can be transferred to or from a control mass.

Around 1600, the English philosopher and scientist Francis Bacon surmised that heat, "itself, its essence and quiddity is motion and nothing else."

The heat added to change the phase of a substance in this way is said to be "hidden," and thus it is called latent heat (from the Latin latere, meaning "to lie hidden").

Convection is usually the dominant form of heat transfer in liquids and gases.

From this he concluded that the heat must have combined with the ice particles and had become latent.

Heat flows between systems that are not in thermal equilibrium with each other; it spontaneously flows from the areas of high temperature to areas of low temperature.