work function

t has been demonstrated that the condition of chemical equilibrium can often be perdicated by thermodynamic considerations and therfore thetendency of areaction to proceed can be measured.The thermodynamic approach dose not however, give any indication of the rate at which a reaction will proceed,and two examples of methallurigically phenomena show the importance of the study of the mechanism and rate of reaction.If aplain carbon steel in the austenitic stracture say at 850c is quenched in watera metastable martensitic structure is produced.this structure will tend to transform to a mixture of ferrite and cementite of lower free energy but the rate of transformation at room tempreature is so slow that the martensite remains apparently unchanged .Tempering at 650 allows the transformation to be completed within an hour.The reaction between carbon and oxygen in liguid steel to form carbon monoxide is accompanid by a substantial negative free energy change but the the carbon and oxygen contents can be raised well above the equilibrium values without any apperciable reaction. If an inrt gas such as argon is bubbled through the liguid steel ,introdusing suitable nuclei for reaction avigorous boil caused by carbon monoxide gas evaluation can be produced , expenditure of an equivalent amount of energy.In order to metal a given mass of ametal,acertain ammount of energy must be supplied-whether by combustion of afuel or the expenditure of electrical energy.
Thermodynamics specifies a "system"as any matter which is being considered which consists of a definite amount of a given substance or substance.The system will have its "surroundings"with which it can exchange energy ,and the system and its surroundings are considered to be isolated they cannot exchange energy with any other system.An example of such asystem would be a steel billet in a reheating furnace-the surroundings of the billet would include not only the structure of the furnace itself,but also the atmosphere inside and outside the furnace,theground on which the furnace stood ,and any other objects which could exchange a measurable amount of energy with the billet , either directly or indirectly.Thus,the First law of thermodynamics states that the total energy of asystem and its surroundings remains constant,evenif it may be changed from one form of energy to another.We can now introduce a quantity U ,which represents the total energy of asystem-whether it be kinetic,electrical,rotational,vibrational,or any other form of energy except the energy due to its position in space,which is assumed to be consta.U is called the internal or intrrinsic energy of the system and is not usually known quantitatively because of the difficulty of measuring all the different forms of energy possesed by actual systems.This is not important because we are concerned with changes in energy ,which can be measured.If the state of a system changes from A to B,for instance as aresult of achange in tempreature,then we say that the change in intrrnal energy is the internal energy in the final state,UB minus internal energy in the initial state UA.measurements if they could be made would apparently give us some information about the structure of molecules of solid and liquids but how can this be done what are the entropy unit s mentioned in the , calssical thermodynamics provides the answer in fact historically this approach came before that of statistical thermodynamics the existence of an entropy function was postulated by the thermodynamicists before its behaviour and singnificance were expanded by this statistical mathematicians,in which the system is changed from a to b and back again even though by two different routes we know from the first law of thermodynamic and the nature of thermodynamic variables that the change in intrernal energy will be zero and that values of preasure and volume will not change as a result of asystem being taken through such a cycle.therfore the work done by the system w must be the same as the heat absorbed by the system in traving such a cycle if we have some sort of machine or heat engine which can convert heat into mechanical work we can define the efficiency of the machine which can be converted into work,This is a law based on experience,and is an extension of the principle of conservation of Energy wich states that energy cannot be created or destroyed,provided that ther is no measurable conversion of mass to energy:it can only be converted from one form to another.The consistency of Joules mechanical equivalent of heat is explained by this principle,and it is clear that if it obeyed,no machine can be devised which will do work without the expenditure of an equivalent amount of energy.In order to metal a given mass of ametal,acertain ammount of energy must be supplied-whether by combustion of afuel or the expenditure of electrical energy.
Thermodynamics specifies a "system"as any matter which is being considered which consists of a definite amount of a given substance or substance.The system will have its "surroundings"with which it can exchange energy ,and the system and its surroundings are considered to be isolated they cannot exchange energy with any other system.An example of such asystem would be a steel billet in a reheating furnace-the surroundings of the billet would include not only the structure of the furnace itself,but also the atmosphere inside and outside the furnace,theground on which the furnace stood ,and any other objects which could exchange a measurable amount of energy with the billet , either directly or indirectly.Thus,the First law of thermodynamics states that the total energy of asystem and its surroundings remains constant,evenif it may be changed from one form of energy to another.We can now introduce a quantity U ,which represents the total energy of asystem-whether it be kinetic,electrical,rotational,vibrational,or any other form of energy except the energy due to its position in space,which is assumed to be consta.U is called the internal or intrrinsic energy of the system and is not usually known quantitatively because of the difficulty of measuring all the different forms of energy possesed by actual systems.This is not important because we are concerned with changes in energy ,which can be measured.If the state of a system changes from A to B,for instance as aresult of achange in tempreature,then we say that the change in intrrnal