Introduction. Strong Electrolyte Weak Electrolyte Dissociation depends on concentration, model as reaction

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1 Introduction Strong Electrolyte Weak Electrolyte Dissociation depends on concentration, model as reaction 1

2 18.2 Colligative properties Electrolyte dissociation changes concentration more than non-electrolyte (large dilution effect). Freezing pt. 5 g each NaCl 58.44g/mol, EG g/mol, glucose 180 g/mol. Tf K K 272.7K 0.1 mole of each Tf K K K smotic pressure, 0.1 mole of each Π 4.89 MPa 2.5 MPa 2.5 MPa Boiling pt elevation, 0.1 mole each Tb 101 C C 100.5C 2

3 18.3 Speciation H 2 l + () H + ( aq) H ( aq) 18.4 K a, 298 H + [ ][ H ] K a, 298 ΔG o 298 exp( RT) a H + a H a H2 3

4 18.4 Concentration Scales and Standard States entity, superficial, apparent, nominal -- true -- molal - m i mol/(kg solvent) molarity - M i mol/l Standard States for electrolytes Standard State for water. K a 298, ( m H +γ H + m H γ H ) ( m o H + m o H a H2 ) m H +m H [ H + ][ H ] 4

5 18.5 Definition of ph ph log 10 ( a H + ) ph log 10 [ H + ] Solvent is important Thermodynamic Network C 2 A ( v) K VLE K SLE C 2 A ( aq) C + aq C 2 A ( s) K a1 + ( ) CA ( aq) K sp K a2 2C + ( aq) + A 2 ( aq) 5

6 18.7 Perspectives on Speciation 2H 2 () l H 3 + aq Charge Balance + ( ) H ( aq) AcH ( aq) + H 2 () l H 3 + aq + ( ) Ac ( aq) 6

7 18.8 Acids and Bases Strong/Weak - Leveling effect - NH 3 + H 2 NH+ 4 + H Strong Acids - completely dissociate, superficial C A [Cl ] C A material balance for complete dissociation K a,w [H + ][H ] equilibrium [H + ] [Cl ] + [H ] charge balance 7

8 Proton Condition - [H + ] C A + [H ] proton condition Condition becomes [H + ] C A + K a,w /[H + ] Strong Bases - e.g. NaH [Na + ] C B material balance for dissociation K a,w [H + ][H ] equilibrium [H + ] + [Na + ] [H ] charge balance Proton Condition [H + ] + C B [H ] proton condition Condition becomes [H + ] + C B K a,w /[H + ] 8

9 Flood diagram log [C(mol/L)] Strong acid Strong Base

10 Weak monoprotic acid - [A ] + [HA] C A material balance K a,a [H + ][A ]/[HA] equilibrium K a,w [H + ][H ] equilibrium [H + ] [A ] + [H ] charge balance [HA] C A [ H + ] ([ H + ] + K aa, ) [ A ] K a, A C A ([ H + ] + K aa, ) undissociated acid (18.30) conjugate base (18.31) 10

11 Weak monoprotic base - [Na + ] [HA] + [A ] C B material balance K a,b [HA][H ]/[A ] equilibrium K a,w [H + ][H ] equilibrium [H + ] + [Na + ] [A ] + [H ] charge balance pk aa, pk ab, + pk aw, or K aa, K ab Use pk a,a to plot, K a, w 11

12 Fluconazole N N N N N N + H 2 Fluconazole + + H H F ln(k a ) /T F 18.9 Sillen Diagrams - seven steps 1. coordinates, strong acid/base lines. 2. material balance. 3. equil in acid form. 5. sketch acid and base equations. 6. proton condition to find intersection. 7. Check 12

13 Example 18.5 C B 1E-2 mol/l NaAc Step 1: The lines for [H + ] and [H ] have been drawn and labeled in the figure. Step 2: [Na + ] [HAc] + [Ac ] C B material balance Step 3: K a [Ac ][H + ]/[HAc] equilibrium K w [H + ][H ] equilibrium Step 4: [H + ] + [Na + ] [Ac ] + [H ] charge balance Proton Condition - eliminate large terms from charge balance 13

14 Polyprotic Acids (H 3 P 4, H 2 P 4, HP 4 2, P 4 3 ) [H 2 P 4 ] [ H 3 P 4 ] [HP 2 4 ] [H 2 P 4 ] [P3 4 ] [HP 2 4 ] K a [ H + ] K a [ H + ] K a [ H + ] or or [HP 2 4 ] [ H 3 P 4 ] [P3 4 ] [ H 3 P 4 ] K a1 K a2 [ H + ] 2 The material balance on phosphorous is K a1 K a2 K a3 [ H + ] 3 C [ H 3 P 4 ] + [ H 2 P 4 ] + [ HP2 4 ] + [P3 4 ] 14

15 α 3 C [ H P 4 ] [ HP ] [P ] [ H 3 P 4 ] [ H 3 P 4 ] [ H 3 P 4 ] [ H 3 P 4 ] K 1 a1 K a1 K a2 K a1 K a2 K a3 [ H + ] [ H + ] 2 [ H + ] 3 [ H α 3 P 4 ] C [ H + ] 3 [ H + ] 3 + K a1 [ H + ] 2 + K a1 K a2 [ H + ] + K a1 K a2 K a3 [ H α 2 P 4 ] [ H P 4 ][ H 2P 4 ] K α a1 C C [ H 3 P 4 ] [ H + ] 15

16 NaH 2 P 4, 1E-2 M, HCl, 5E-3 M E-3 log[c(mol/l)] ph [H + ] [H ] [H 3 P 4 ] [H 2 P 4 ] [HP 4 2 ] 2 1 [P 3 4 ] [H + ]+[H 3 P 4 ]

17 Amino Acids, N H 2 H CH, pk a,a 2.35 NH 2, pk a,a 9.78 glycinium glycine glycinate H 2 Gly + HGly Gly ph < < ph < 9.78 ph > H 3 NCH 2 CH + H 3 NCH 2 C H 2 NCH 2 C pk a 2.35 pk a 9.78 H 2 N pk a,a H 2 N Lysine (Lys, K) H H pk a,a 3.9 H 2 N H NH H 2 N Tryptophan (Trp, W) Aspartic Acid (Asp, D) H 17

18 0.1 M Glycine ph log[c(mol/l)]

19 Buffers Isoelectric point mg N/cm Salting In 0.005N 0.01N 0.02N 0.001N ph Salting ut 19

20 Donnan Equilibria membrane impermeable to DNA α side Na + Cl Cl Na + β side Cl zna + Na + Cl DNA z- Na+ Na + Cl Cl Na + 20

21 Solubility and Ksp Fluconazole, Example 18.8 and ln(k SLE ) /T K SLE a fluc( aq) K a,a [fluc][h + ]/([fluc + ]a H2 ) 21

22 Common Ion Effect KCl s + K sp a K +a Cl ( ) K + ( aq) Cl ( aq) 22

23 Redox reactions - ILRIG Methane combustion - Li-Ion battery - LiC 6 C 6 + Li + + e,, Co 2 + Li + + e LiCo 2 LiC 6 + Co 2 C 6 + LiCo 2 Half-cell rxns, relative to 2H + + 2e - H 2 g ( ) 23

24 E E red E ox Potential per electron! Voltage and Gibbs Energy Faraday constant - 96,485 J/V. ΔG n e FE red + n e FE ox (equilibrium condition - dead when K a is reached. or ΔG Balancing, including non-redox. n e FE RTlnK a v v ΔG ΔG + RTln a i i n e FE n e FE RTln a i i RT v E E a i v n e F ln i E a i n log i e Nernst Eq. 24

25 Alkaline Battery Zn (s) and γ-mn 2(s) Zn (s), α-mnh (s). E E Fuel Cell a Zn a log MnH 2 a Zn a Mn2 a H2 Biological Reactions Degree of reduction C d H a b N c γ red (4d + a 2b)/d Glucose --> Ethanol 25

26 Binding polynomials P 3 4 binding receptor for H + ligands K bind a1 1 K a3 C [ P 3 4 ] 1 i + [ H + ] [ H + ] [ H + ] 3 K a3 K a3 K a2 K a3 K a2 K a1 [ P 3 4 ] 1 K bind a1 H + ( + [ ] + K bind a1 K bind a2 [ H + ] 2 + K bind a1 K bind a2 K bind a3 [ H + ] 3 ) ( 01 ( ) + 1K 1 [ H + ] + 2K 2 [ H + ] 2 + 3K 3 [ H + ] 3 ) t P 1 bind i 0 P bind ik i [ x] i [ x] dp bind dx [ ] P bind dlnp bind dln[ x] 26

27 Energy Carriers catabolic - anabolic exergonic - energonic coupling - ATP NADP P - P - P N NH 2 N N 5' 4' 1' H H H 3' 2' H H H N Adenosine Adenine D-Ribose ATP 4, HATP 3, H 2 ATP 2, H 3 ATP, H 4 ATP, H 5 ATP + Standard State Nicotinamide (oxidized) - P P - H H H 2 N N N H N + H P - - N N NH 2 D-Ribose D-Ribose H N Adenine (reduced) H NH 2 27

28 Transformed Gibbs Energy (1) Constant ph, pmg (2) Use apparent concentrations [ATP] sum of all ATP species ΔG ATP ΔG + RT [] i ν i ln ΔG RTlnK c i + H 2 ADP+ H 3 P 4 or ATP + H 2 ADP + P i [ ADP] [ P K c i ] [ ATP] ΔG f, ADP + ΔG f, Pi ΔG f, ATP ΔG exp f, H RT 28

29 Biological Fuel Cells Glucose --> Gluconolactone 2 --> H 2 2 Non-ideal Solutions μ i μ i + RTln( m i γ i ) air sat d V e glucose a 1 a 1 or m 1 γ 1 c 1 γ 1 ø Real Solution For biology, usually a ø 1 Ideal Solution m 1 or c 1 standard state concentration m 1 or c a 1 29

30 r r 2 r 2 Φ ρ ± ( r) r ε r is radial position, Φ is electric potential, ρ ± (r) is charge distribution as a function of radial distance, ε ε o D, where ε o is the permittivity of a vacuum and D is the dielectric constant g(r) ~ exp( u Coul /kt) z log 10 γ i2 A γ I i Ba I log 10 γ s Φ up to I 0.1 m 2A γ M w, s Ba I 1000( Ba) lna s M w s, m i electrolytes ln( 1 + Ba I) 1 + Ba I osmotic coefficient 30

31 M w, s m i RT electrolytes Π Φ osmotic pressure V s 1000 Gibbs energies for electrolytes ΔG T RT NC ΔG T ln a RT i ΔG o 298 G f, 298 H + G f, 298 H + i 1 [ ] ν i Δ ( ) + ΔG f, 298 ( H ) ΔG o f, 298 ( H 2 () l ) Δ ( ) + ΔG f, 298 ( H ) kj/mol 31

32 Transformed Gibbs Energies G' U TS + PV N H μ H + N Mg μ Mg 2+ Δ G f, T, j I Δ ΔG f T i,, N H, i G f, T, H + I N Mg, i G f, T, Mg 2+ I G f j,, ( I ph pmg) ΔG f, T, i () I { Δ () RTpH c ln( 10) } { Δ () RTpMgln( 10) } () ΔG f, T, j ( I0) RTln( 10)z j2 A γ ( I ( 1 + Ba I) ) T, ( I0) ΔG f, , j ( I0) T ΔH f, , j ( I0) 32

33 Gibbs Energies of Pseudoisomers ΔG f, T, i ( I, ph c, pmg) G f T i( 1) G f, i( 1) Δ Δ,, ( I, ph c, pmg) RTlnP bind Δ G P bind 1 + exp f, i( 2) RT ΔG f, i( 1) ΔG + exp f, i( 3) + RT P bind K a3 K a3 K a2 K a3 K a2 K a1 ( 1 + K bind a1 + K bind a1 K bind a2 + K bind a1 K bind a2 K bind a3 ) 1 G r j exp Δ f, i( 1) ΔG f, i() j RT ΔG f, T, i ΔG exp f, i() j ( RT) P bind Example, ph c 7, pmg c 3, I 0.25 mol/kg 33

34 [ ATP 4 ] P i P bind [ HATP ] [ MgATP] P i P i [ MgATP 2 ] P i ΔG f, Pi ΔG f, Pi ( 1) RTlnP bind ( ) ln kj/mol 34

35 Coupled Reaction and Phase Equilibria (Ideal Solutions only) Cl 2(aq) + H 2 H + + Cl + HCl (aq) K a1 a H +a Cl a HCl ( aq) a Cl2 a ( aq) H2 1E HCl (aq) H + + Cl a K H + a Cl a a HCl ( aq) 1Ε a H 2 H + + H K H +a H w Write the VLE as reactions H 2 ( v) H 2 l () a H2 1E-14 K w a W /(y w P) 1/ (P w sat ) 35

36 Cl 2( v) Cl 2( aq) K H [Cl 2(aq) ]/(y Cl2 P), Henry s Law ph [HCl] log[c(mol/l)] [Cl ] [H ] -6 [H + ]

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Introduction. Strong Electrolyte Weak Electrolyte Dissociation depends on concentration, model as reaction Speciation

Introduction. Strong Electrolyte Weak Electrolyte Dissociation depends on concentration, model as reaction Speciation Introduction Strong Electrolyte Weak Electrolyte Dissociation depends on concentration, model as reaction 8.2 Colligative properties Electrolyte dissociation changes concentration more than non-electrolyte