The molecular interpretation of Entropy S=k.InW Statistical thermodynamics possible positions of molecules S→ Energies of molecules volume (pressure) In general,the number of microstates lS←-temperature available to a system will increase with number 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 ofpositions and energies of molecules in the system
The molecular interpretation of Entropy S k = ⋅ln W In general, the number of microstates Statistical thermodynamics possible positions of molecules S Energies of molecules → volume pressure ( ) S temperature ← 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. S temperature number ←
Entropy s← possible positions of molecules Energies of molecules 1.For any substance: gas Solid Liquid H,0(S)→H,0① △S>0 Solid Liquid Gas Liquid Vapor Standard Entropy Values (S)for Some Substances at25°C Substance S(J/K·mol) _Boiling H2O() 69.9 H2O(g) 188.7 Br2(l) 152.3 Br2(g) 245.3 I2(S) 116.7 Melting I2(8) 260.6 Temperature(K)
Entropy 1. For any substance: solid liquid gas S < S S << 2 2 H O ( ) H O ( ) s l S>0 → ∆ possible positions of molecules S Energies of molecules ←
Entropy possible positions of molecules S→ Energies of molecules 2.For a substance in the same state: Solid Liquid Gas For liquid H2O(D) _Bolling Sgoc >Ssoc 3.In dissolving process: Solute:in much more random Melting Temperature (K) and disordered state. Solvent o o00000809o Water:hydration process, in more ordered state. Solute Solution Net result:depends!In generally: △S(dissolving)>0
Entropy 2. For a substance in the same state: high Temperature low Temperature S > S 80 C 50 C For liquid H O(l): 2 S >S ° ° 3. In dissolving process: possible positions of molecules S Energies of molecules → 3. In dissolving process: Solute: in much more random and disordered state. Water: hydration process, in more ordered state. Net result: depends！ In generally: ∆S (dissolving) > 0
Entropy Entropy (S):a measure of the randomness or disorder of a system 4.Gases are formed from solid or liquid: CaCO;(s)->CaO(s)+CO(g) 5.Mole number of gaseous substances increases in a chemical reaction 2C(s)+02(g)→2CO(g) C,H,④+15/0，(8)→6C0,(g)+3H,0☑ AgCl(s)Ag"(aq)+Cl(aq) Ca (PO)(s)3Ca2(aq)+2PO (aq) N2(g)+O2(g)→2NO(g)
Entropy (S) : a measure of the randomness or disorder of a system 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 ( ) 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 →