Unit -2 THEORY OF DILUTE SOLUTIONS

Transcription

1 Uit - THEORY OF DILUTE SOLUTIONS 1) hat is sluti? : It is a hmgeus mixture f tw r mre cmpuds. ) hat is dilute sluti? : It is a sluti i which slute ccetrati is very less. 3) Give a example fr slid- slid sluti : Cpper disslved i gld. 4) Give a example fr gas- gas sluti : ixture f xyge ad itrge gases. 5) Give a example fr gas- slid sluti : Sluti f hydrge i palladium. 6) Give a example fr liquid- slid sluti : malgam f mercury with sdium. 7) Give a example fr liquid- liquid sluti : Ethal disslved i water. 8) Give a example fr slid- gas sluti : Camphr i itrge gas. 9) Defie mle fracti ad give the equati t calculate it. [] :le fracti is the rati f umber f mles f e cmpet t the ttal umber f mles f all the cmpets i the sluti. X = + X = + 10) Defie mlarity ad give the equati t calculate it. [] : Number f mles f the slute preset per liter sluti is kw as mlarity. = V 11) Defie mlality ad give the equati t calculate it. [] : Number f mles f the slute preset perkgslvet is kw as mlality. =

2 1) Defie the term slubility f a substace. : Slubility f a substace is its maximum amut that ca be disslved i a specified amut f slvet at a specified temperature 13) State Hery s law. [] : Hery s Law: t cstat temperature slubility f a gas i a liquid is directly prprtial t the partial pressure f gas preset abve the sluti. OR t cstat temperature the partial pressure f the gas i vapr phase (p) is prprtial t the mle fracti f the gas (x) i the sluti. athematically p x ; p = K H x. here K H is Hery s law cstat. K H depeds the ature f the gas. 14) rite the plt which shws relati betwee partial pressure f a gas v/s its mle fracti. [] : artial pressure f a gas le fracti. 15) eti the factrs affectig slubility f a gas i liquid. [] : 1. Temperature. ressure 16) Explai hw temperatures effect the slubility f a gas i liquid. [] : Slubility f gases i liquid decreases with rise i temperature. ccrdig t Le Chatelier s riciple,as dissluti is a exthermic prcess, the slubility shuld decrease with icrease f temperature. 17) Explai hw pressure effects the slubility f a gas i liquid. : The slubility f gases icreases with icreases f pressure. 18) eti the applicatis f Hery s law. [3] : (a) T icrease the slubility f CO isft drik ad sda water, the bttle is sealed uder high pressure.

3 (b) T avid beds, as well, the txic effects f high ccetrati f itrge i the bld, the taks used by scuba divers are filled with air dilute with helium. (c) t high altitudes the partial pressure f xyge is less tha that at the grud level. This leads t lw ccetratis f xyge i the bld ad tissues f peple livig at high altitudes r climbers. 19) State Rault slaw f liquid- liquid dilute slutis. [] : The partial vapur pressure f each cmpet f the sluti is directly prprtial t its mle fracti preset i sluti. Thus, fr cmpet 1 1 x1 d p1 = p1 0 x1 0) hat are ideal slutis? : The sluti which bey Raul s law ver the etire rage f ccetrati are kw as ideal sluti 1) eti the characters f ideal slutis. [3] : Ideal I. It beys Raults law is beyed at all temperature ad ccetrati = + II. V mix = O i.e., there is chage i vlume mixig III. Hmix = O i.e., there is ethalpy chage whe ideal sluti frmed IV. It des t frm azetrpic mixture V. Frce f attracti betwee, is similar as ) hat are - ideal slutis? : he a sluti des t bey Rault s law ver the etire rage f ccetrati, the it is called - ideal sluti. 3) eti the types f - ideal slutis. : There are tw types (a) N- ideal sluti with psitive deviati frm Rault s law (b) N- ideal sluti with egative deviati frm Rault s law 4) Give a example fr - ideal sluti with psitive deviati frm Rault s law. : ixtures f ethal ad acete

4 5) Give a example fr - ideal sluti with egative deviati frm Rault s law. : example f this type is a mixture f phel ad ailie. 6) hat are azetrpes? Give example. [] : zetrpes are biary mixtures havig the same cmpsiti i liquid ad vapur phase ad bil at a cstat temperature. Fr example: ethal- water mixture 7) State Rault s law f relative lwerig f vapur pressure. : Relative lwerig f vapur pressure is equal t the mle fracti f the slute. 8) Defie clligative prperty. : The prperties deped the umber f slute particles irrespective f their ature relative t the ttal umber f particles preset i the sluti. Such prperties are called clligative prperties 9) eti fur clligative prperties f dilute slutis. [] : Relative lwerig f vapur pressure I. Elevati i ilig pit II. III. Depressi i Freezig pit Osmtic pressure 30) Defie the term relative lwerig f vapur pressure. [] : It is the rati f lwerig f vapur pressure t the vapur pressure f the pure slvet = Relativelwerig f V. 31) hat is elevati i bilig pit? : Elevati i bilig pit is the differece betwee the bilig pit f the sluti ctaiig - vlatile slute ad the bilig pit f the pure slvet Tb = T T 3) Give the relati betwee elevati i bilig pit ad mlecular mass f slute. [] : w 1000 ΔT b = K b w 1 here w is mass f slute, w 1 is the mass f the slvet; is mlar mass f the slute

5 33) Give the S.I.uit f ebulliscpic cstat r bilig pit elevati cstat r mlal elevati cstat. : The uit f Kb is K kg ml ) hat is depressi ifreezig pit? : It is the decrease i the freezig pit f sluti whe - vlatile slute is added it slvet. 35) Give the relati betwee depressi ifreezig pit ad mlecular mass f slute.[] : ΔT f = K f w w Kf 1000 w = Δ T w f 1 where is mlar mass f the slute. Nte: Values f K f ad K b f the slvet depeds their mlecular mass ad ΔH fusi ad ΔH vap f the slvet respectively. 36) Give the S.I.uit f cryscpic cstat. : The uit f Kf is K kg ml ) Draw the plt shwig elevati i bilig pit i a sluti. [] : Slvet Sluti Vapur pressure T b 0 Temperature/K Tb T b

6 38) Draw the plt shwig depressi i freezig pit i a sluti. [] Vapur pressure Frze slvet Liquid slvet Sluti Tf T f Temperature/K T f 39) Defie smsis. : The prcess f mvemet f slvet particles frm lwer ccetrati t higher ccetrati thrugh semi- permeable membrae t attai equilibrium is called smsis. 40) hat is smtic pressure ad give its relati with ccetrati f sluti. [] : The amut f exteral pressure required t stp the smsis. = CRT here: = smtic pressure, R = gas cstat, T = temperature, C = ccetrati f sluti. 41) hat are istic slutis? : Tw differet slutis havig samesmtic pressure are called istic slutis 4) hat are hypertic slutis? : The sluti havig mre smtic pressure tha ther 43) hat are hyptic slutis? : The sluti havig less smtic pressure tha ther

7 44) Explai the applicati f reverse smsis i desaliati f water. [] : he pressure mre tha smtic pressure is applied, pure water is squeezed ut f the sea water thrugh the membrae. variety f plymer membraes are available fr this purpse. The pressure required fr the reverse smsis is quite high. wrkable prus membrae is a film f cellulse acetate placed ver a suitable supprt. Cellulse acetate is permeable t water but impermeable t impurities ad is preset i sea water. 45) hat is reverse smsis? : vemet f slvet particles frm higher ccetrati t lwer ccetrati thrugh a semi permeable membrae, whe pressure is applied greater tha smtic pressure 46) hat is abrmal mlar mass? : mlar mass that is either lwer r higher tha the expected r rmal value is called as abrmal mlar mass. 47) Defie Vat hff factr Va t Hff factr i t accut fr the extet f assciati r dissciati f a slute i a slvet is i = r i = r i = Nrmal mlar mass brmal mlar mass bserved clligative prperty calculated clligative prperty ttal umber f mles f particles after assciati r dissciati Number f mles f particles befre assciati r dissciati 48) hat is the value f i fr NaCl. : 49) hat is the value f i fr KSO4. : 3

8 50) hat is the value f i fr sugar. : 1 51) hat is the value f i fr glucse. : 1 5) O what factr the clligative prperty depeds. : It depeds umber f mles f slute particles but t the ature f the slute. 53) rite the mathematical equati f Raults law i case f - vlatile slute. : If e f the cmpets (slute) is - vlatile the the equati f Raults law is. = O = + = + O = = O. X 54) rite the differetiate betwee - ideal slutis with psitive deviati ad egative deviati frm Rault s law [] sitive deviati (a)i this sluti slvet slute iteracti is weaker tha slvet slvet, slute- slute iteractis (b) > + (c) V > O (d) H = psitive (e) It frms azetrpe with miimum bilig pit Negative deviati (a) I this sluti slvet slute iteracti is strger tha slvet slvet, slute- slute iteractis (b) < + (c) V < O (d) H = egative (e)it frms azetrpe with maximum bilig pit 55) Defie lwerig f vapur pressure? : It is defied as the differece betwee the vapr pressure f the slvet i pure state ad the vapur pressure f the sluti = 56) State Rult s law f relative lwerig f vapur pressure : It states that the relative lwerig f vapur pressure is equal t the mle fracti f the slute

9 57) hy sea water freezes belw 0 0 C? : Sea water freezes belw 0 0 C due t the presece f the - vlatile slute disslved i the water. 58) Derive the equati t calculate mlecular mass f ukw slute usig Rault s law f relative lwerig f V. [3] : ccrdig t Rault s law relative lwerig f vapur pressure is equal t the mle fracti f the slute. = X = + <<< fr dilute sluti S we ca eglect i demiatr = = =. =

10 Numerical prblems 1. sluti ctaiig.56 g sulphur i 100 g CS gave a freezig pit lwerig f K. Calculate the mlar mass f sulphur mlecules. Give K f f CS = 3.83 K kg ml 1. s. ΔT f = K, K f = 3.83 K kg ml 1 ΔTf = K f m ; ΔTf = K f (mlar mass f sulphur mlecules) = = 56 g ml g f water has 3g f urea disslved i it. Calculate the freezig pit f the sluti. K f fr water = 1.86 K kg ml 1, mlar mass f urea = 60 g ml 1, freezig pit f water = K (0 C) s. ΔT f = K f m ; ΔT f = 1.86 ΔT f = = ΔT f = T T T f = = 7. r 0.93 C f f 3. Huma bld has smtic pressure f 7. atm at bdy temperature f 37 C. Calculate the mlar ccetrati f slute particles i bld. Give R = L atm K 1. π s. π = CRT ; C = T = = 310 K RT C (mlar ccetrati) = 7. = Vapur pressure f bezee is 00 mm f Hg. g f a - vlatile slute i 78 g bezee has vapur pressure f 195 mm f Hg. Calculate the mlar mass f the slute. lar mass f bezee = 78 g ml 1. s. = ; 1 = ; = lar mass f slute ( ) = 00 = 80 g ml 1 5

11 g f water ctaiig 7 g f a - vlatile slute will bil at C. Calculate the mlar mass f the slute. Give bilig pit f water = 100 C, K b = 0.5 K kg ml 1. s. ΔT b = K b m ; ΔT b = K b lar mass f slute ( ) = = 180 g ml