Colligative properties

Transcription

1 Coigative properties HYSICL CHEMISRY, nd course Degree in haracy COLLIGIVE ROERIES Definition of Coigative roperty Vapour ressure Lowering Freezing oint Depression (Cryoscopy) oiing oint Eevation (Ebuioscopy) Osotic ressure Coigative roperties of Eectroyte Soutions ppications Suary and Concusions 1

2 COLLIGIVE ROERIES he word coes fro the Latin "coigatus that eans together. hese properties : depend ONLY on the nuber of soute partices. do NO depend on the nature of the soute. 3 COLLIGIVE ROERIES he soutions have certain characteristics: the soute is NO VOLILE. the soid soute does NO dissove into the soid sovent. 4

3 COLLIGIVE ROERIES hese properties are studied in :. NON- ELECROLYE Soutions.. ELECROLYE Soutions. 5 COLLIGIVE ROERIES VOUR RESSURE LOWERING FREEZING OIN DERESSION (CRYOSCOY) OILING OIN ELEVION (EULLIOSCOY) OSMOIC RESSURE 6 3

4 COLLIGIVE ROERIES Definition of Coigative roperty Vapour ressure Lowering Freezing oint Depression (Cryoscopy) oiing oint Eevation (Ebuioscopy) Osotic ressure Coigative roperties of Eectroyte Soutions ppications Suary and Concusions VOUR RESSURE LOWERING he presence of the soute reduce the sovent tendency to go to the vapour phase. 7 4

5 VOUR RESSURE LOWERING ure sovent Soution of a nonvoatie soute 9 VOUR RESSURE LOWERING Idea and idea diute soutions Δ Δ - - Δ Rea soutions (1 - a ) (1 - ) 10 5

6 VOUR RESSURE LOWERING Idea and idea diute soutions Δ re - - Δ re Rea soutions Δ re 1 - a 1-11 COLLIGIVE ROERIES VOUR hase ure sovent () SOLUION Non-Voatie Soute Voatie Sovent () SOLUION Non-Voatie Soute Voatie Sovent () SOLID hase ure sovent () Non-voatie soute he soute does not dissove in the soid sovent he vapour curve does not change he soid curve does not change 1 6

7 COLLIGIVE ROERIES Soid Liquid Soution R og Vapour f f b b Depression Eevation 17 COLLIGIVE ROERIES he change in affects the freezing point and the boiing point G S S vapour S iquid S soid 18 7

8 Sovent vapour pressure (orr) COLLIGIVE ROERIES 760 Soid Liquid Vapour soution * pure sovent * b pure sovent eperature ( C) b b soution 19 COLLIGIVE ROERIES Definition of Coigative roperty Vapour ressure Lowering Freezing oint Depression (Cryoscopy) oiing oint Eevation (Ebuioscopy) Osotic ressure Coigative roperties of Eectroyte Soutions ppications Suary and Concusions 8

9 FREEZING OIN DERESSION his property appears when there is phase equiibriu SOLUION Non-Voatie Soute Voatie Sovent () SOLID has ure sovent () between soution and the pure sovent in soid state pure soidifies fro the soution when it is cooed 1 FREEZING OIN DERESSION IDEL SOLUION (s) so (s) o() og og o() (s) og *() (s) 9

10 FREEZING OIN DERESSION IDEL SOLUION og *() (s) R og ΔG, og ΔG, 3 FREEZING OIN DERESSION IDEL SOLUION og ΔG, og ΔG, ΔG, 4 10

11 FREEZING OIN DERESSION IDEL SOLUION og ΔG, ΔG, og ΔS, ΔG, og, 5 FREEZING OIN DERESSION IDEL SOLUION og og 1 dog,, d og R, 1 1, og R,,, 6 11

12 FREEZING OIN DERESSION IDEL SOLUION og R Δ,,,, og og R, R Δ, Δ fus, fus, fus 7 FREEZING OIN DERESSION IDEL DILUE SOLUIONS og (1 ) 1! og (1 3! 3 ) 6 4! 4... Δ,, R 3 M

13 FREEZING OIN DERESSION IDEL DILUE SOLUION Δ M 10 3,, Δ K c K c M 10, 3, 9 FREEZING OIN DERESSION REL SOLUION (s) so (s) o() og a og a o() (s) og a *() (s) 30 13

14 FREEZING OIN DERESSION REL SOLUION og a *() (s) og a ΔG, og a, 31 FREEZING OIN DERESSION REL SOLUION og a og 1 dog a,, d og a R, Δ, og a R Δ,, og 3 14

15 COLLIGIVE ROERIES Definition of Coigative roperty Vapour ressure Lowering Freezing oint Depression (Cryoscopy) oiing oint Eevation (Ebuioscopy) Osotic ressure Coigative roperties of Eectroyte Soutions ppications Suary and Concusions OILING OIN ELEVION his property appears when there is phase equiibriu VOUR hase ure sovent () SOLUION Non-Voatie Soute Voatie Sovent () between soution and the pure sovent in the vapour state pure vaporizes when the soution is heated 34 15

16 OILING OIN ELEVION IDEL SOLUION (v) so (v) o() og (v) o() og (v) *() og 36 OILING OIN ELEVION IDEL SOLUION (v) *() og ΔGvap, og og vap, 37 16

17 OILING OIN ELEVION IDEL SOLUION og b dog og 1 b, vap, d og R vap, Δb b, b Δ b b - b, og R Δ b, vap, b 38 OILING OIN ELEVION IDEL DILUE SOLUION og (1 ) 1! og (1 3! 3 ) 6 4! 4... R Δ b, vap, b 3 M

18 OILING OIN ELEVION IDEL DILUE SOLUION Δ b M 10 3 vap, b, Δ K b b K b M 10 b, 3 vap, 40 OILING OIN ELEVION REL SOLUION (v) so (v) o() og a (v) o() og a (v) *() og a 41 18

19 OILING OIN ELEVION REL SOLUION (v) *() og a ΔGvap, og a og a vap, 4 OILING OIN ELEVION REL SOLUION og a b dog a og 1 b, vap, d og a R vap, Δb b, b og a R Δ b, vap, b og 43 19

20 COLLIGIVE ROERIES Definition of Coigative roperty Vapour ressure Lowering Freezing oint Depression (Cryoscopy) oiing oint Eevation (Ebuioscopy) Osotic ressure Coigative roperties of Eectroyte Soutions ppications Suary and Concusions OSMOIC RESSURE Sovent () Soution (D) his property appears when theres is phase equiibriu between soution and the pure sovent in iquid phase 45 0

21 OSMOIC RESSURE Sovent () Soution (D) ebrane rigid V = constant diathery = D seipereabe ony aows to pass through 46 OSMOIC RESSURE Sovent Seipereabe ebrane Soution 47 1

22 49 Seipereabe ebrane Soution Sovent Seipereabe ebrane Soution Sovent Osotic ressure OSMOIC RESSURE 51 IDEL SOLUION OSMOIC RESSURE ) (, ) (, β () α () β () α () og ) (, ) (, β () α () og ) (, ) (, * * V

23 OSMOIC RESSURE IDEL SOLUION () (, ) β () (, α ) V π () (, ) α () (, ) og β - og V π 53 OSMOIC RESSURE IDEL DILUE SOLUION og (1 ) V π c V π c Van't Hoff Equation 54 3

24 OSMOIC RESSURE REL SOLUION () () (, α α ) (, ) () () (, β β ) (, ) og a () (, ) β () (, ) V α ( β α ) () (, ) β () (, ) V α π - og a - og V π 55 OSMOIC RESSURE Water oecue Soute oecue Isotonic soution Hypotonic soution Hypertonic soution 56 4

25 OSMOIC RESSURE Water fow direction Drinking sea water causes dehydration. 60 OSMOIC RESSURE in hypotonic soution Isotonic soution in hypertonic soution 61 5

26 OSMOIC RESSURE Isotonic soution Hypotonic soution Hypertonic soution 6 COLLIGIVE ROERIES Definition of Coigative roperty Vapour ressure Lowering Freezing oint Depression (Cryoscopy) oiing oint Eevation (Ebuioscopy) Osotic ressure Coigative roperties of Eectroyte Soutions ppications Suary and Concusions 6

27 COLLIGIVE ROERIES ELECROLYE SOLUIONS Coigative properties are proportiona to the concentration of LL soute partices (ION + MOLECULES) he dissociation of eectroytes odify the vaue of the coigative properties of a soution. One ust distinguish between: Idea diute soutions of eectroytes Rea soutions of eectroytes 64 COLLIGIVE ROERIES ELECROLYE SOLUIONS. IDEL DILUE SOLUION: he effective concentration is greater than the rea concentration. he Van't Hoff factor, i, needs to be introduced. 65 7

28 COLLIGIVE ROERIES ELECROLYE SOLUIONS M X - M z X z t 0 t t eq (1- α) 0 α 0 α efect (1- α α) (1 α( 1)) i (1- α) α α i 1α( 1) 66 COLLIGIVE ROERIES ELECROLYE SOLUIONS Vapour pressure owering Idea diute soution: Δ i * Freezing oint Depression (Cryoscopy) Idea diute soution: oiing point eevation (ebuioscopy) Idea diute soution: Δ Δ b K K c b i i Osotic ressure Idea diute soution: π c i 67 8

29 COLLIGIVE ROERIES ELECROLYE SOLUIONS For a eectroyte copetey dissociated: i = ν Vapour pressure owering Idea diute soution: Freezing oint Depression (Cryoscopy) Idea diute soution: * Δ Δ K oiing point eevation (ebuioscopy) c Idea diute soution: Osotic ressure Idea diute soution: Δ K b b π c 68 COLLIGIVE ROERIES ELECROLYE SOLUIONS. REL SOLUION: he effective concentration is greater than the rea concentration. he epressions are the sae that the ones for a rea soution, but now the vaues depend on the tota nuber of partices 69 9

30 COLLIGIVE ROERIES ELECROLYE SOLUIONS. REL SOLUIONS: og a og a Δ (1 - a ) Δ, Δb b,, vap, - og a V π 70 COLLIGIVE ROERIES Definition of Coigative roperty Vapour ressure Lowering Freezing oint Depression (Cryoscopy) oiing oint Eevation (Ebuioscopy) Osotic ressure Coigative roperties of Eectroyte Soutions ppications Suary and Concusions 30

31 LICIONS Deterination of soutes oecuar weight. ntifreeze copounds. scent of sap. Mechanica stabiity of the pants. Use of sat and sugar to preserve food. Gherkin in vinegar. Reverse ososis. 71 OSMOIC RESSURE Reverse Ososis: Water urification Seipereabe ebrane Seawater 73 31

32 OSMOIC RESSURE Reverse Ososis: Water urification Seipereabe ebrane ressure greater than 30 at Seawater ure water 74 COLLIGIVE ROERIES Definition of coigative property Vapour ressure Lowering Freezing oint Depression (Cryoscopy) oiing oint Eevation (Ebuioscopy) Osotic ressure Coigative roperties of Eectroyte Soutions ppications Suary and Concusions 3

33 SUMMRY ND CONCLUSIONS VOUR RESSURE LOWERING: Idea and an idea diute soution: Δ * Rea Soution: Δ (1 - a ) Eectroyte soutions: Δ i * SUMMRY ND CONCLUSIONS FREEZING OIN DERESSION ND OILING OIN ELEVION (s) (v) so () b b 33

34 SUMMRY ND CONCLUSIONS FREEZING OIN DERESSION : Idea soution: Idea diute soution: Rea Soution: Eectroyte soution: og og a Δ K Δ Δ c, Δ K c, i,, SUMMRY ND CONCLUSIONS OILING OIN ELEVION (EULLIOSCOY): Idea soution: Idea diute soution: Rea Soution: Eectroyte soution: og og a Δ K Δ Δb b b b, Δb b K b b, i vap, vap, 34

35 SUMMRY ND CONCLUSIONS Osotic RESSURE: Idea soution: - og V π Idea diute soution: π c Rea Soution: - og a V π Eectroyte soution: π c i 35