6.152J3.155J Thermodynamics and phase diagrams 6.12J/3.155JMi Hn -h.=AH= heat of formation wAH of b from a Do all reactions that give off heat proceed? SB-SA=AS=Entropy(disorder)change s[/B from a to b Do all reactions that increase disorder proceed? Answer in Gibbs free energy = Gn -G=4G=AH. TAS G must decrease if reaction is to proceed (From equilibrium, all changes increase G N。v.26,2003 Thermodynamics and phase diagrams 6.12J/3. 155J Microelectronic processing AH= of b from a h Do all Exothermic exothermal reactions Configuration AS=from a to b B△S>0 △S<0 → ordered Does disorder al ways increase AG=AH-T4 Will not go Will not go above T=H/AS belOw T=AH/AS Examples: freezing of water melting of copper Nov.26,20036.152J/3.155J 2 3 Nov.26 , 2003 6.12J / 3.155J Microelectronic processing Thermodynamics and phase diagrams HB - HA = DH = heat of formation of B from A Do all reactions that give off heat proceed? SB - SA = DS = Entropy (disorder) change from A to B Do all reactions that increase disorder proceed? ¨S A B S Configurations H A B ¨H G = H - TS GB - GA = DG = DH - TDS G must decrease if reaction is to proceed. (From equilibrium, all changes increase G). A B G Answer in Gibbs free energy: 4 Nov.26 , 2003 6.12J / 3.155J Microelectronic processing DH = of B from A DS =from A to B ¨S < 0 B more ordered A B S Configurations H A B ¨H DG = DH - TDS Will not go above T = DH /DS A B G Exothermic Do all exothermal reactions proceed? ¨S > 0 B more disordered A B S Configurations H A B ¨H Will not go below T = DH /DS A B G Endothermic Does disorder always increase in reactions? Examples: freezing of water melting of copper Thermodynamics and phase diagrams