7/27/2019 State the Laws of Thermodynamics

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1.)State the laws of Thermodynamics. Zeroth law of thermodynamics:The zeroth law in its wider sense

establishes a notion of internal thermodynamic equilibrium of a

system.[7]

In a narrow sense, the law states that if two systems are

both in thermal equilibrium with a third system then they are

inthermal equilibriumwith each other. This law helps define the

notion oftemperature.

First law of thermodynamics:The first law establishes a notionofinternal energyfor athermodynamic system.Heat and work

are forms of energy transfer. The internal energy of a

thermodynamic system may change as heat or matter are

transferred into or out of the system or work is done on or by the

system. All the energy transfers must be accounted for to see that

there is strictconservation of the total energyof a thermodynamicsystem and its surroundings. The law implies thatperpetual

motion machinesof thefirst kind,which would do work without

using the energy resources of a system, are impossible.

Second law of thermodynamics:An isolated physical system, if notalready in its own internal state of thermodynamic equilibrium,

spontaneously evolves towards it. In an isolated physical system,

there is a tendency towards spatial homogeneity. In particular,

when an isolated physical system reaches its own internal state of

thermodynamic equilibrium, its temperature is spatially uniform.When work is done on or by a thermodynamic system, a certain

amount of that energy is lost to inefficiency, related to the

difference between the energy level of the input and the output.

This loss is described by the notion of entropy, which is often used

to express the law. Some of the loss is due to friction when work

is done, and some of it may be due to the relaxation of the system

towards spatial homogeneity.

The law says that these two mechanisms occur always andinevitably. The law implies thatperpetual motion machinesof

thesecond kindare impossible.

Third law of thermodynamics:There are various ways ofexpressing the third law.

[8]They derive from the statistical

mechanical explanation of thermodynamics. They refer to

ideally perfect theoretical models of physical systems. A

common expression of the law states that no practicable

means can bring a physical system to an exactly zero

absolute thermodynamic temperature.

2.)Differentiate Exothermic and Endothermicreaction.

An exothermic reaction releases energy; in exothermicreactions, heat is a product while An endothermic

reaction absorbs energy; in endothermic reactions, heat

is a reactant.

3.)Difference between specific heat and heatcapacity.

Heat Capacity: ratio of the amount of energy absorbed to

the associated temperature rise.

Specific Heat: the heat capacity of a substance per unit

mass.

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