Physical Chemistry Chapter 3 Chapter 3 The Second Law of Thermodynamics Reaction The first law The second law N2+3H2→>2NH3Ess+Em (with a catalyst)constant Provide such information 2leq INH ? througl th s ec
1 Chapter 3 The Second Law of Thermodynamics Reaction The first law The second law N2+3H2 2NH3 (with a catalyst) Esys + Esurr =constant [N2]eq =? [H2]eq =? [NH3]eq =? Provide such information through S Physical Chemistry Chapter 3
Physical Chemistry Chapter 3 The Statements of second law a It is impossible for a system to undergo a cyclic process whose sole effects are the flow of heat into the system from a heat reservoir and the performance of an equivalent amount of work by the system on the surroundings Kelvin-Plank statement Heat g Cyclic Heat inmachine b wOrk output =q reservoir (system) Fig3.1
2 The Statements of Second Law § It is impossible for a system to undergo a cyclic process whose sole effects are the flow of heat into the system from a heat reservoir and the performance of an equivalent amount of work by the system on the surroundings. Kelvin-Plank statement Physical Chemistry Chapter 3 Heat reservoir Cyclic machine (system) Work output = q Fig. 3.1 Heat q
Physical Chemistry Chapter 3 The Statements of second law It is impossible for a system to undergo a cyclic process whose sole effects are the flow of heat into the system from a cold (heat) reservoir and the flow(performance )of an equal equivalent amount of heat(work)out of(by the) system into a hot reservoir (on the surroundings. Clausius statement (Kelvin-Plank statement)
3 The Statements of Second Law § It is impossible for a system to undergo a cyclic process whose sole effects are the flow of heat into the system from a cold (heat) reservoir and the flow (performance) of an equal equivalent amount of heat (work) out of (by the) system into a hot reservoir. (on the surroundings.) Clausius statement (Kelvin-Plank statement) Physical Chemistry Chapter 3
Physical Chemistry Converts some of the random Chapter 3 molecular energy of heat flow into HEAT ENGINES macroscopic mechanical energy ( work) a heat engine operating Heat reservoir at T e between two temperatures The heat and work quantities q are for one cycle Engin ●●● (3.1) C Cold reservoir TC gH t qc (32) Fg.32 qH e +gC=l qc <1 (3.3) qH qH
4 HEAT ENGINES H C H H C q q q q q e 1 (3.3) Heat reservoir at TH Cold reservoir at TC qH -qC -w Fig. 3.2 Heat Engine A heat engine operating between two temperatures. The heat and work quantities are for one cycle. H qH w q w e | | (3.1) -w = qH + qC (3.2) < 1 Physical Chemistry C Chapter 3 onverts some of the random molecular energy of heat flow into macroscopic mechanical energy (work)
Physical Chemistry Chapter 3 Carnot's Principle Carnot Principle: No heat engine can be more efficient than a reversible heat engine when both engines work between the same pair of temperatures The maximum amount of work from a given supply of heat is obtained with a reversible engine
5 Carnot’s Principle Carnot Principle: No heat engine can be more efficient than a reversible heat engine when both engine s work be twe en the s ame pa ir of temperatures. The maximum amount of work from a given supply of heat is obtained with a reversible engine. Physical Chemistry Chapter 3