Heat

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Thermodynamics

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Means movement of heat. It is the study of the relationship between heat and energy.

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Zeroth Law of Thermodynamics

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Zeroths law of thermodynamics states : If A and B are in thermal equillibrium with a third body then A and B are in thermal equillibrium with each other.

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Thermal Equillibrium

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If a hot body and a cold body are brought in contact with each other, the cold body absorbs heat and the hot body emits heat. This process is continued until both bodies are at the same temperature.

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Heat

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Heat is a form of energy, it produces the sensation of warmth. It is the measure of the total energy content of the molecules in an object and its S.I unit is Joules while its CGS Unit is Ergs. It is the cause.

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Temperature.

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It is the degree of hotness or coldness of a body. It is the measure of average kinetic energy in the molecules of an object and is measured in C or F (S.I unit is Kelvin) It is the effect.

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Conduction

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Conduction is a process of heat transfer from in solids, in which heat is transferred from particle to particle of the solid, without any actual movement of particles.

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Conductor

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Materials that allow heat to passs through them. The best conductors are metals since the electrons which carry electric current can also carry energy from hot parts to cold parts.

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Insulators

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Materials that do not allow heat to pass through them. Gases are a good example of insulators, since the molecules which make them up are relatively far apart and do not collide often.

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Convection

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It is the transfer of heat through a body by the hot particles themselves moving from place to place. Transfer of heat by convection takes place in liquids and gases only. It does not occur in solids since the particles are not free to move about.

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Specific Heat Capacity

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Specific heat capacity is the quantity of heat required to raise the temperature of a unit mass of substance through one degree Celcius or 1 Kelvin.

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Waters Specific Heat Capacity

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4200 J Kg(-1)

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Principle Of Calorimetry

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AKA as the First Law of Thermodynamics. It states that the heat lost by a hot body is equal to the heat gained by a cold body when they are kept in contact together (assuming tere is no heat lost to the surroundings)

m1c1θ1 = m2c2θ2

Where :

m1 = Mass of hot body.

c1 = Specific heat capacity of hot body

θ1 = Change in temperature of mass m1

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Melting

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The transformation of a substance from solid to liquid is called melting

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Melting point

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The te,perature at which a solid melts is called the melting point or melting temperature of the substance. It is the constant temperature at which it changes from solid to liquid.

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Solidification or Freezing

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The change of fluid (liquid state) into solid state.

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Freezing point.

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The temperature at which a liuquid solidifies is called the freezing point or solidification temperature. (most substances solidify at the same temp that they melt.) Water crystallises into ice at 0*C. Pure iron melts at 1539*C.

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Vaporisation

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The change from liquid to vapour.

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Condensation

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The change from vapour to liquid,

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Sublimation

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The change of state of a solid directly into its Gaseous state and Vice-Versa without going through liquid state.

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Latent Heat

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The amount of heat needed to change the state of a given substance without any change in temperature is called the Latent Heat.

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Specific Latent Heat

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The amount of heat needed to change the state of a unit mass of a substance without any change in temperature is called the Specific Latent Heat.

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Specific Latent Heat of Fusion

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The quantity of heat necessary to convert unit mass of a solid(crystalline) substance into a liquid at constant temperature. it is denoted by "L"

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Regelation.

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It is the increase of melting point with Pressure. For example. some ice at 0 degree C is subjected to (external) pressure. It melts to form water which is at a temperature below 0*C , due to the applied pressure. When the pressure is released, the water (below 0*C) refreezes to form ice at 0*celsius. Movement of Glaciers and Ice Skating is possible due to this phenomenon.