Thermodynamics 热力学 Laws of Thermodynamics show that spontaneity is predictable by considering two factors: Enthalpy Entropy 焙H S熵 Enthalpy Change (AH): Entropy(⑨： the total energy difference the randomness factor accounts between reactants and products for energy lost in the process Gibbs Free Energy (G):net amount available Energy for useful work after considering the two factors
Thermodynamics Laws of Thermodynamics show that spontaneity is predictable by considering two factors: Enthalpy & Entropy H S Enthalpy Change (∆H) : Entropy (S) : 热力学 焓 熵 Enthalpy Change (∆H) : the total energy difference between reactants and products Entropy (S) : the randomness factor accounts for energy lost in the process Gibbs Free Energy (G) : net amount available Energy for useful work after considering the two factors
The molecular interpretation of Entropy S=k.InW Statistical thermodynamics volume (pressure) S←-temperature the number of molecules In general,the number of microstates available to a system will increase with an increase in volume,an increase in temperature,or an increase in number of molecules;because any of these changes will increase the possible arrangements of positions and energies of molecules in the system
The molecular interpretation of Entropy S k = ⋅ln W Statistical thermodynamics volume pressure ( ) S temperature the number of molecules ← In general, the number of microstates available to a system will increase with an increase in volume, an increase in temperature, or an increase in number of molecules; because any of these changes will increase the possible arrangements of positions and energies of molecules in the system
Entropy s← possible positions of molecules Energies of molecules 1.For any substance: 88 Liquid Solid Liquid Vapor Ssolid STigeid gas Solid Liquid Gas Standard Entropy Values (S)for Some Substances at25°C Substance S(J/K·mol) H20I) 69.9 H20(8) 188.7 Boiling Br2(l) 152.3 Br2(8) 245.3 I2(S) 116.7 2(g) 260.6 Melting Temperature(K)
Entropy 1. For any substance: solid liquid S S possible positions of molecules S Energies of molecules ← liquid gas < S S <
Entropy S→ possible positions of molecules Energies of molecules 2.For a substance in the same state: Solid Liquid Gas For liquid water: S.oox>SH.o0x5o _Boiling 3.In dissolving process: Solvent 0000889o .Melting Qoooooooo 0o099990 Temperature(K) Solute Solution Solute:in much more random Water:hydration process is in and disordered state. more ordered state. Net result:depends In general☑y:△S(dissolving)>0
Entropy 2. For a substance in the same state: 2 2 S >S (H O(l))( ) (H 80 C 50 ° ° O(l ( )) ) C 3. In dissolving process: possible positions of molecules S Energies of molecules → For liquid water: Solute: in much more random and disordered state. Net result: depends！ In generally: ∆S (dissolving) > 0 Water: hydration process is in more ordered state
Entropy 4.Gases are formed from solid or liquid: CacO(s)->Cao(s)+CO2(g) 5.Mole number of gaseous substances increases in a chemical reaction 2C(s+0,(g)→2CO(8g) C。H,①+1530，(g)→6C0,(g)+3H,00 AgCl(s)Ag"(aq)+Cl(aq) Ca,(P04)2(s)=3Ca2+(aq)+2P0(aq) N2(g)+O2(g)→2NO(g)
Entropy 4. Gases are formed from solid or liquid: 3 2 ( ) ( ) ( ) CaCO s CaO s CO g → + ∆ 5. Mole number of gaseous substances increases in a chemical reaction 2C(s)+O ( ) 2 ( ) 2 g CO g → 6 6 2 2 2 15 C H (l)+ O ( ) 6 ( ) 3 ( ) 2 g CO g H O l → + + - AgCl(s) (aq) + Ag Cl (aq) 2+ 3 4 2 3- Ca (PO ) (s) ( Ca P 4 3 aq) + (aq) 2 O N (g)+O (g) 2NO(g) 2 2 →