Chapter 19 Chemical Thermodynamics .Spontaneous Processes ·Entropy 2nd Law of Thermodynamics ·Calculation of△S ·Gibbs Free Energy△G Free Energy and Temperature 。△G&the Equilibrium Constant K
Chapter 19 Chemical Thermodynamics • Spontaneous Processes • Entropy • 2nd Law of Thermodynamics • Calculation of ∆S • Gibbs Free Energy ∆G • Free Energy and Temperature • ∆G & the Equilibrium Constant K
Spontaneous vs.Non-spontaneous Spontaneous process A process,once started,proceeds on its own without outside influence. .Non-spontaneous process: A process requires external help for it to proceed. Spontaneous Nonspontaneous
Spontaneous vs. Non-spontaneous • Spontaneous process : A process, once started, proceeds on its own without outside influence. • Non-spontaneous process spontaneous process : A process requires external help for it to proceed
Is this a spontaneous process? Other Factor Transferring heat from a hot object to a cold object. Yes,always. Spontaneous for T>0C Spontaneous for T<0C H>0? H<0? 。Ice melting. Water freezing. Yes,ifT>OC Yes,ifT<0C No,ifT<OC ifT=0C No,ifT>OC
Is this a spontaneous process? • Transferring heat from a hot object to a cold object. Yes, always. Other Factor ? • Ice melting. Water freezing. Yes, if T > 0oC No, if T < 0oC Yes, if T < 0oC No, if T > 0oC if T = 0 oC ? ∆H > 0 ? H > 0 ? ∆H < 0 ? H < 0 ?
Thermodynamics Laws of Thermodynamics show that spontaneity is predictable by considering two factors: ENTHALPY&ENTROPY S Enthalpy Change (AH)total Entropy (S)randomness energy difference between factor accounts for energy reactants products lost in the process Gibbs Free Energy (G):net amount available Energy for useful work after considering the two factors Thermodynamics:a study of energy flow as well as how much energy can be converted to useful work
Thermodynamics Laws of Thermodynamics Laws of Thermodynamics show that show that spontaneity is predictable by considering two factors: ENTHALPY& ENTROPY H S Enthalpy Change (∆H) : total Entropy (S) : randomness factor accounts for energy Thermodynamics: a study of energy flow as well as how much energy can be converted to useful work Enthalpy Change (∆H) : total energy difference between reactants & products factor accounts for energy lost in the process Gibbs Free Energy (G) : net amount available Energy for useful work after considering the two factors
Why consider spontaneity of reactions? Spontaneity:the tendency in nature for certain things to take place >Can make use of this tendency to work for us. To know the amount of useful work to expect from a reaction. What is the maximum amount of Energy I can get out ofone tank of gasoline? Useful work obtained through a spontaneous combustion reaction of Thermodynamics one tank of gasoline
Why consider spontaneity of reactions? • Spontaneity: the tendency in nature for certain things to take place Can make use of this tendency to work for us. To know the amount of useful work to expect from a reaction. What is the maximum amount of Useful work obtained through a spontaneous combustion reaction of one tank of gasoline. What is the maximum amount of Energy I can get out of one tank of gasoline ? Thermodynamics