Bi Tp Cn Bng Cht t Tan

Bi Ton V Tan
Bi 1: (HPT-205) Tnh tan ca PbI2 pH = 6 . Bit pT(PbI2) = 7,86 ; lg[Pb(OH)+] = -7,8
/s: S = 1,52.10-3M
Bi 2: (HPT-205) Tnh tan cua FeS pH = 5. Bit pT(FeS) = 17,2 ; pka1(H2S) = 7,02 , pka2(H2S) = 12,9 , lg[Fe(OH)+]
= -5,92
/s: S= 2,43.10-4M
Bi 3: (HPT-206) Tnh tan ca HgS trong nc. Bit pT(HgS) = 51,8 ; lg[Hg(OH) +] = -3,65 ; pka1(H2S) = 7,02 ,
pka2(H2S) = 12,9
/s: S = 7,6.10-22M
Bi 4: (HPT-207) Tnh tan ca Fe(OH)3 trong dung dch bo ha Fe(OH)3. Bit pT(Fe(OH)3) = 37,5 ; lg[Fe(OH)2+] =
-2,17 ; Kn = 10-14.
Bi 5: (HPT-208) Tnh tan ca AgI trong NH3 1M. Bit pT(AgI) = 16 ; pka(NH4+) = 4,76 ; lg[Ag(NH3)+] = 3,32 ;
lg[Ag(NH3)2+] = 7,24.
/s: S = 4,2.10-5M
Bi 6: (GT-108) Tnh tan ca Calci oxalate trong dung dch pH = 4. Bit T(CaC 2O4) = 2,3.10-9 ; pka1(H2C2O4) = 4,27 ;
pka2(H2C2O4) = 1,25.
/s: S = 8,1.10-5M
Bi 7: (GT-108) Tnh tan ca Cu Strong nc bit T(CuS) = 6,3.10-36 ; pka1(H2S)= 7,0 ; pka2(H2S) = 12,89 ; Hng s to
phc Hydroxo ca Cu2+ l: lg1 = 7,0 ; lg2 = 13,68; lg3 = 17,0 ;lg4 = 18,5.
/s: S = 10-14,36M
Bi 8: (GT-128) Trong nc Zn(OH)2 c 2 cn bng
Zn(OH)2 Zn2+ + 2OH- ; Ks = 10-17 v Zn(OH)2 + 4H2O Zn(OH)42- + 2H3O+ ; Ks = 10-29
Tnh tan nh nht ca Zn(OH)2 .
Bi 9: (HPT-210) Tnh tch s tan iu kin v tan ca PbI2 trong dung dch CH3COONa 1M v CH3COOH 1M . Bit
pT(ZnS) = 7,86 ; lg[Pb(OH)+] = -7,8 ; lg[Pb(CH3COO)+] = 2,52 ;pka(CH3COOH) = 4,76 .
/s: T = 10-5,34 v S = 10-2M
Bi 10: Tnh nng Ag+ trong dung dch bo ha hn hp ta AgCl v AgBr . Bit T(AgCl) = 1,82.10-10 ; T(AgBr) =
5,2.10-13.
Bi 11: Tnh tan ca AgCl trong KCl 0,1M .Bit T(AgCl) = 1,82.10-10
Bi 12: (HPT-258) Tnh tch s tan iu kin ca Fe(OH)3 trong dung dch NaF 1,0M v NaOH 0,01M .Tnh pH ca dung
dch v tan ca Fe(OH)3
Bi ton v iu kin xut hin ta kt ta hon ton

Bi 13: (HPT-216) Trn 1,00 ml MgCl2 0,02M vi 1,00ml hn hp NH3/NH4Cl ng mol 2M . C xut hin kt ta hay
khng? Bit pT(Mg(OH)2) = 4,76 ; lg[Mg(OH)+] = -12,8 ; pkb(NH3) = 4,76
/s: khng xut hin kt ta.
Bi 14: Cn thm bao nhiu ml dung dch NH3 25% vo 100ml dung dch MgCl2 0,1M xut hin kt ta ? Kt ta hon
ton ? ( Coi th tch khng i )
Bi 15: Cho 7,8g Na2S vo 1 lt dung dch [Zn(NH3)4]Cl2 0,1M c hin tng kt ta khng ? Bit T(ZnS) = 4,5.10-24 ,
lg[Zn(NH3)2+] = 2,4 ; lg[Zn(NH3)22+] = 4,8 ; lg[Zn(NH3)32+] = 7,3 ; lg[Zn(NH3)42+] = 9,4; T(Zn(OH)2) = 1,2. 10-17
Bi 16: Nh t t AgNO3 vo dung dch NaCl 0,01M v NaBr 0,0005M . Kt ta no xut hin trc ? Nng Cl - trong
dung dch phi bng bao nhiu 2 kt ta xut hin cng lc ? Bit T(AgCl) = 1,82.10 -10 , T(AgBr) = 5,2.10-13
Bi 17: Cho dung dch cha FeSO4 0,1M v ZnSO4 0,1M . iu chnh pH trong dung dch bng bao nhiu khi sc H2S
n bo ha vo dung dch ( [H2S] = 0,1M ) m khng xut hin kt ta? (b qua s to phc hydroxo) Bit T(ZnS) =
4,5 .10-24 ; ka1(H2S) = 10-7 , ka2 = 1,3.10-13.
Bi 18: (HPT-234) Trn 1ml hn hp m NH3 2M v NH4NO3 2M vi 1,00ml dung dch B gm FeCl3 0,002M v NaF
0,2M . C xut hin ta hay khng? Bit lg[FeF2+] = 5,18 ; lg[FeF2+] = 9,07 ; lg[FeF3] = 12,1 ; pka(NH4+) = 4,76.
pT(Fe(OH)3) = 37
Bi 19: (HPT-243) Tnh nng ca Na2CO3 phi ly 1lit dung dch ny kt ta hon ton 0,010 mol CaSO4 (Coi
H2SO4 l acid 2 nc phn li hon ton) .Bit pT(CaCO3) = 8,3 ; pka1(H2CO3) = 6,35 ; pka2(H2CO3) = 10,33.
Bi 20: (HPT-258) Sc H2S bo ha lin tc vo dung dch CuCl2 0,01M ; HCl 0,2M ; FeCl3 0,01M v ZnCl2 0,01M v
MnCl2 0,01M th c hin tng g xy ra . Bit nng H2S bo ha trong dung dch l 0,1M . Cho T(CuS) = 6.10-36 ;
T(FeS) = 6.10-8 ; T(ZnS) = 4,5.10-24 ; T(MnS) = 3.10-13 ; pka1(H2S) = 7,02 ; pka2(H2S) = 12,9 v E0(Fe3+/Fe2+) = 0,771V v
E0(S/S2-) = -0,51V
Bi ton kt ta phn on
Bi 21: Dung dch gm Zn2+ 0,02M v Cd2+ 0,02M bo ha lien tc bng H2S ( [H2S] = 0,1M ). iu chnh pH kt ta
ti a CdS m khng lm kt ta ZnS ? Tnh nng Cd2+ cn li khi ZnS bt u kt ta .(Mt ion c coi l kt ta
hon ton khi nng ca n 10-6 M.) Bit T(ZnS) = 4,5.10-24 , T(CdS) = 2.10-28 ; pka1(H2S) = 7 ; pka2(H2S) = 12,9
Bi 22: Dung dch A cha Fe3+ 0,01M v Cu2+ 0,01M Nh t t NaOH vo dung dch . Hi kt ta no xut hin trc ?
C th tch hon ton 2 ion trn trong dung dch bng OH- khng? Bit T(Fe(OH)3) = 2.10-39 v T(Cu(OH)2) = 4,8.10-20. .
(Mt ion c coi l kt ta hon ton khi nng ca n 10-6 M.)
Bi 23: (K65 m 6504) C th thc hin c s phn chia nh lng c Cl - v I- bng cch kt ta bi ion Cu+ t 1
dung dch c nng cc anion trn u bng 0,1M . Nu s phn chia ny c th thc hin c th cc gii hn ca
Cu2+ l bao nhiu ? .(Mt ion c coi l kt ta hon ton khi nng ca n 10 -6 M.). Bit T(CuCl) = 1,2.10-6 ;
T(CuI) = 1,2.10-12 .
Bi tp t cc thi HSG-THPT
Bi 5: (T214) Cho CO2 li qua dung dch gm Ba(OH)2 0,1M v Sr(OH)2 0,1M . Cht no kt ta trc ? Khi mui th 2
bt u kt ta th t l mui th nht cn li trong dung dch l bao nhiu ? V c th dng s kt ta phn on tch
ring 2 ion Ba2+ v Sr2+ ra khi dung dch c khng ?. Bit T(BaCO3) = 8,1.10-9 ; T(SrCO3) = 9,4.10-10.
/s: - SrCO3 kt ta trc
-

Khi BaCO3 bt u kt ta th % Sr2+ cn li trong dung dch l 11%

Khng dng phng php kt ta phn on tch ring 2 ion Sr2+ v Ba2+ ra khi dung dch c.

Bi 6: (T219) FeS v CuS , cht no c kh nng tan c trong dung dch HCl ? Hy chng minh. Bit
T(FeS) = 5.10-8 ; T(CuS) = 3,2.10-38 ; pka1(H2S) = 9 , pka2(H2S) = 13
/s: FeS tan c ; CuS khng tan c
Bi 8: (T225-226) Tnh tan ca FeS pH = 5 . Bit T(FeS) = 10-17,2 ; pka1(H2S) = 7,02 ; pka2(H2S) = 12,92
Qu trnh to phc hidroxo ca Fe2+ : Fe2+ + H2O Fe(OH)+ + H+ ; * = 10-5,42
Bi 11: (T244-245) Dung dch cha Ag+ 10-3 M v NH3 1M .
a, Tnh nng cc dng phc c trong dung dch ( thi im cn bng)
Bit 1( [Ag(NH3)]+ ) = 103,92 ; 2( [Ag(NH3)2]+ ) = 107,24 ; pkb(NH3) = 4,76 . B qua s to phc hidroxo.
b, Trn ng th tch KCl 0,02M v dung dch vo dung dch [Ag(NH3)2]NO3 0,02M c xut hin kt ta khng? Bit
T(AgCl) = 1,56. 10-10
/s : a, [Ag(NH3)+2] = 10-3M , [Ag(NH3)+] = 1,2.10-7M , [Ag+] = 5,7.10-11M
b, C xut hin ta .
Bi 13: (T263) Cho H2S li qua dung dch cha Cd2+ 0,01M v Zn2+ 0,01M n bo ha ( [H2S] = 0,1M )
a, Thit lp khu vc pH trong dung dch sao cho xut hin ta CdS m cha xut hin ta ZnS .
b, Thit lp khu vc pH m ti ch cn 0,1% Cd2+ m Zn2+ vn khng b kt ta .
Bit pka1(H2S) = 7,02 , pka2 (H2S) = 12,90 ; T(CdS) = 10-26 , T(ZnS) = 10-21,6 ; ( Cd(OH)+ ) = 10-10,2 ,(Zn(OH)+) = 10-8,96
/s a, -1,54 < pH < 0,66
b, 0,04 < pH < 0,66
Bi 16: (T275)
a, Cho cn bng sau 25oC xy ra trong dung dch nc :
Pb(OH)2 (r) + 2I- (d.d) PbI2 (r) + 2OHC kt ta PbI2 khng nu dung dch bo ha Pb(OH)2 c cha KI 0,1M ?
b, Tnh nng ti thiu ca HNO3 Pb(OH)2 bt u phn ng vi H+ theo phn ng Pb(OH)2 (r) + 2H+ Pb2+ + H2O
Bit T(Pb(OH)2) = 4.10-15 , T (PbI2) = 8.10-9
/s : a, C kt ta

; b, C(HNO3) > 10-5M th bt u c phn ng .

Bi 18: (T291) Tnh tan ca CuS trong

a, dung dch HCl 1N

b, Dung dch HNO3 1M

Bit: T(CuS) = 10-35,2 ; pka1(H2S) = 7 , pka2(H2S) = 12,92 ; E0(NO3-,H+/NO) = 0,96V , E0(H2S/S) = 0,14V
Cu2+ + nCl- [CuCln] (n-2)- (n: 1 4) lg1 = 2,8 , lg2 = 4,4 , lg3 = 4,89 , lg4 = 5,62

/s: a, S = 1,66.10-5M b, phn ng oxy ha kh xy ra hon ton .

Bi 20: ( T298) Tnh tan ca AgSCN trong dung dch NH3 0,003M .
Bit T(AgSCN) = 1,1.10-12 v hng s phn li ca phc [Ag(NH3)2+] = 6.10-8
/s S = 1,27.10-5M
Bi 23: (T310) Mt dung dch cha BaCl2 0,01M v SrCl2 0,1M . Tnh pH c th lm kt ta hon ton Ba2+ di dng
BaCrO4 m khng lm kt ta SrCrO4 bng dung dch K2Cr2O7 1M .
Bit T(BaCrO4) = 10-9,93 , T(SrCrO4) = 10-4,65 v Cr2O72- + H2O 2CrO42- + 2H+ ; K = 10-14,64.
/s 3,39 < pH < 3,67
Bi 26: (T15)
Hidroxyapatit Ca5(PO4)3OH c trong thnh phn men rng . Trong ming, cc ion Ca2+ v PO43- c trong nc bt tham gia
vo vic to thnh v phn hy Hidroxyapatit . Ion OH- trong Hidroxyapatit c th thay th bng ion F - to thnh Floapatit
Ca5(PO4)3F c tan nh hn.
a, Tnh tan ca Ca5(PO4)3OH v Ca5(PO4)3F trong nc
b, Tnh hng s ca phn ng to thnh Ca5(PO4)3F t Ca5(PO4)3OH.
Bit T(Ca5(PO4)3OH ) = 6,8.10-37 ; T(Ca5(PO4)3F) = 10-60.
/s : a, S(Ca5(PO4)3OH) = 2,7.10-5M ; S(Ca5(PO4)3F) = 6,1.10-8 ; b, K= 6,8.1023
Bi 27: (T46) Tnh %AgCl b mt i khi ra 0,451g hp cht ny bng
a, 200ml nc ct

b, 150ml NH 4Cl ri ra tip bng 50ml nc ct.

Bit T(AgCl) = 10-9,75

/n : a, %AgCl (mt i) = 0,085% ; b, %AgCl (mt i) = 0,021%
Bi 28: (T47) Dng 200ml dung dch NH4NO3 (d=1g/ml) ra kt ta MgNH4PO4. Tnh C% (kl/kl) ca dung dch
NH4NO3 khi ra kt khng mt qu 0,01mg MgO. Bit T(MgNH4PO4) = 2,5.10-13.
/n : 1,28%
Bi 30: (T62) Trn 1ml MgCl2 0,01M vi 1ml dung dch NH3 1M v NH4Cl 2M . C kt ta Mg(OH)2 khng ?
Bit T(Mg(OH)2) = 10-10,95 ; pka(NH4+) = 9,24
/s : khng xut hin ta
Bi 31: (T62) Thm t t tng git AgNO3 vo dung dch cha KCl 0,1M v KI 0,001M . Kt ta no xut hin trc ?
Khi kt ta th hai bt u tch ra th nng ion th nht cn li bao nhiu? Bit T(AgCl) = 10 -10 ,T(AgI)= 10-16
/s : AgI kt ta trc , khi AgCl bt u kt ta th I- kt ta hon ton .
Bi 33: (T112-113) Trong dung dch Al(OH)3 tn ti 2 cn bng
Al(OH)3 Al3+ + 3OH- ; T1 = 10-33

OH- + Al(OH)3 AlO2- + 2H2O ; T2 = 40

 pH no th tan ca Al(OH)3 cc tiu ? Tnh tan ti pH ?

/s : pH = 5,5 , S = 1,5.10-7M
Bi 34: (T121) Tnh tan ca CuS trong dung dch bo ha H2S ( [H2S]=0,1M ) v c mt HCl 0,15N .
Bit T(CuS) = 6,3.10-36 ; pka1(H2S) = 7 , pka2(H2S) = 12,92
/s S = 1,7.10-16M
Bi 36: (T180) Dung dch A cha ng thi Ag+ 0,004M v Cl- 0,001M . cn thm NH3 vo dung dch n nng bao
nhiu ha tan hon ton kt ta .Bit T(AgCl)=1,8.10-10 , 2 [Ag(NH3)2+] = 107,24
/s: C(NH3) = 0,0365M
Bi 37: (T180) Bit tan ca H2S trong dung dch HClO4 0,003M l 0,1M . Nu thm vo dung dch ny cc ion Mn2+
v Cu2+ sao cho nng ca chng u bng 2.10-4M (th tch khng i) th thy xut hin kt ta. xc nh thnh phn
ca kt ta thu c.
Bit pka1(H2S) + pka2(H2S) = 20,89 ; T(MnS) = 3.10-14 , T(CuS) = 8.10-37
/s: CuS
Bi 39: (T194-195) Trong nc Fe3+ b thy phn theo cn bng: Fe3+ + H2O Fe(OH)2+ + H+ ; K = 10-2,2 . Hi FeCl3
nng no th bt u xut hin kt ta Fe(OH)3 . Bit T(Fe(OH)3) = 10-38.. Tnh pH khi ?
/s: C(FeCl3) = 5,56.10-2M , pH = 1,8
Bi 44: (T342) Tnh pH bt u kt ta v kt ta hon ton Fe 2+ bng H2S bo ha. Bit C(Fe2+) = 0,01M , nng H2S
bo ha bng 0,01M . Bit pka1(H2S) = 7,02 , pka2(H2S) = 12,9 ; pT(FeS) = 17,2. Kt ta c coi l hon ton khi [Fe 2+]
10-6 M.
/s: pH (bt u kt ta) = 2,9 , pH (kt ta hon ton) pH > 4,9
Bi 46: (T348-349) Tnh tan trong nc v pH ca dung dch bo ha Fe(OH) 2 . Bit T(Fe(OH)2) = 10-15,1 v (Fe(OH)
+
) = 10-5,92
/s: S = 10-3,51 , pH = 10,49
Bi 55: (T399-400)
a, Dung dch bo ha CaSO3 c pH = 8,63 ( dung dch X). Bit pka1 = 1,76 , pka2 = 7,20 .Tnh T(CaSO3)
b, Cho thm NaOH vo dung dch X n nng 10-4M vo 1 lt dung dch X . Tnh [Ca2+] bit [HSO3-] = 10-4
/s: a, T = 1,416.10-8 ; b, [Ca2+] = 1,124.10-7 M
Bi 59: (T418) Mt dung dch cha 350 mmol Na2S2O3 v mt lng cha xc nh KI. Chun dung dch ny vi
AgNO3 th thy dng ht 20mmol AgNO3 trc khi bt u vn c . Tnh s mol KI Bit th tch sau chun l 200ml .
Bit hng s khng bn ca Ag(S2O3)23- l 6.10-14 v T(AgI) = 8,5.10-17
/s: 17mmol
Bi 63: (T441-442) Cho 2 mui Ag2SO4 v SrSO4 vo nc khuy n khi t c trng thi bo ha .Xc nh nng
Ag+ v Sr2+ c trong dung dch khi . Bit T(Ag2SO4) = 1,5.10-5 v T(SrSO4) = 2,8.10-7.

/s : [Ag+] = 3,1.10-2 M ; [Sr2+] = 1,8.10-5 M

Bi 64: (T442) Dung dch bo ha H2S c nng 0,1M. Bit pka1(H2S) = 7 , pka2(H2S) = 12,89
a, Tnh [S2-] trong dung dch bo ha H2S c pH=2
b, Mt dung dch A cha Mn2+, Co2+ , Ag+ vi nng mi ion ban u u bng 0,01M .Ha tan H2S vo A n khi bo
ha ng thi iu chnh pH=2 th ion no b kt ta?
/s: a, [S2-] = 1,3.10-17 M ; b, Co2+ v Ag+ b kt ta
Bi 75: (T488) Tnh pH bt u xut hin kt ta v kt ta hon ton MnS t dung dch MnCl 2 10-2 M bng dung dch
H2S bo ha [H2S] = 0,1M (coi th tch khng thay i khi cho H2S vo).Mn2+ c coi l kt stuar hon ton khi nng
trong dung dch ca n di 10-6 M.Cho pT(MnS) = 9,6 ; pka1(H2S) = 7 ; pka2(H2S) = 12,92
/s: bt u ta pH > 6,76 ; Ta hon ton pH > 10,32
Bi 77: (T510) Tnh s mg SrSO4 chuyn thnh SrCO3 khi lc SrSO4 vi 3ml Na2CO3 2M cho n bo ha. Bit T(SrSO4)
= 3,2.10-7 , T(SrCO3) = 1,1.10-10 ; pka1(H2CO3) = 6,35 , pka2(H2CO3) = 10,33 v Coi nh HSO4- phn ly hon ton .
/s: 1,104 mg
Bi 80: (T548) Dung dch bo ha H2S c nng [H2S] = 0,1M . ha tan H2S vo dung dch cha 3 ion Mn2+ , Co2+, Ag+
c cng nng 0,01M ng thi iu chnh pH=2 th c kt ta no tch ra? Bit T(MnS) = 2,5.10 -10 , T(CoS) = 4.10-21 ,
T(AgS) = 6,3.10-50
/s: CoS v AgS
Bi 83: (T568) Cho dug dch AlCl3 0,01M. Khi cho NaOH vo dung dch tm ln lt cc gi tr pH Al(OH) 3 bt u
kt ta , kt ta hon ton ,bt u tan v tan hon ton. Cho pT(Al(OH) 3) = 32,6 ; K=[H+].[Al(OH)4-] = 10-13,9.(Mn+ coi l
khng cn trong dung dch khi nng ca n < 10-5 M).
/s: pH1 = 3,8 ; pH2 = 4,8 ; pH3 = 8,9 ; pH4 = 11,9
Bi 85: (T569) M t v gii thch hin tng trong th nghim sau:
Dung dch A cha S2- 0,01M , Cl- 0,01M .Cho t t AgNO3 vo dung dch A, sau thm tip KCN t t n d vo dung
dch. Cho pT(AgCl)=10 , T(Ag2S) = 49,7 ; lg[Ag(CN)2] = 21,1
/s: Ban u xut hin kt ta en AgS ri tip n l kt ta trng ca AgCl sau khi thm KCN vo th AgCl tan dn
(do to phc) cui cng cn li mu en do Ag2S khng tan trong KCN.
Bi 88: (T585-586) Dung dch A gm Ba(NO3)2 0,12N v AgNO3 0,012N.
a, Thm tng git K2CrO4 vo dung dch A n d c hin tng g xy ra ? Kt qu ta no xy ra trc?
b, Thm 50ml dung dch K2CrO4 0,54N vo 100ml dung dch A. Tnh nng cc ion thu c.
Cho pka(HCrO4-) = 6,5 v BaCrO4 + H2O Ba2+ + HCrO4- + OH- ; K1 = 10-17,43
Ag2CrO4 + H2O 2Ag+ + HCrO4- + OH- ; K2 = 10-19,50
/s: a, BaCrO4 kt ta vng trc ri n Ag2CrO4 kt ta.
b, [OH-] = [HCrO4-] = 3,8.10-5 M , [CrO42-] = 0,0459M , [K+] = 0,18M ,[Ag+] = 4,66.10-6 M, [Ba2+] = 2,55.10-9 M

Bi 90: (T593-594) Cho pT(CaC2O4) = 8,75 ; pka1(H2C2O4) = 1,25 , pka2(H2C2O4) = 4,27

a, Tnh tan ca CaC2O4 trong nc v trong dung dch HCl 0,1M .
b, Tnh nng H+ t nht cn cho vo dung dch gm CaCl2 0,01M v K2C2O4 0,01M khng xut hin ta
c, Dung dch K2C2O4 0,01M , CaCl2 0,01M , HCl 0,01M th c xut hin ta khng.
/s: a, Trong nc: S = 2,31.10-3M ; Trong dung dch HCl: S = 2,92.10-3M
b, [H+] 0,385M ; c, Xut hin ta .
Bi 92: (T623) Tnh tan ca AgSCN trong dung dch NH3 0,003M . Bit T(AgSCN) = 1,1.10-12 v hng s khng bn
ca phc [Ag(NH3)2]+ bng 6.10-8.
/s: S= 1,27.10-5M
Bi 94: (T657) Khi cho dung dch kim hoc dung dch H2S vo dung dch Cd2+ th s c kt ta trng Cd(OH)2 hoc kt
ta vng nhng khi cho vi git dung dch kim long vo dung dch A c cha K2[Cd(CN)6] 0,05M v KCN 0,1M khng
thy xut hin ta trng , cn khi cho H2S vo A th li c kt ta vng to thnh. Hy gii thch kt qu th nghim trn.
Bit T(Cd(OH)2) = 2,2.10-14 , T(CdS) = 8.10-27 , hng s khng bn [Cd(CN)4]2- bng 7,8.10-18.
/s: iu kin to kt ta Cd(OH)2 l [OH-] 4,742.10-3M Khi cho vi git vo dung dch kim long vo A nng
OH- cha vt ngng nn khng xut hin ta
iu kin to ta CdS l [S2-] 7,273.10-18M Ch cn cho vi git dung dch H2S vo A l nng S2- vt
ngng xut hin ta vng ngay lp tc.
Bi 101: (T761) Dung dch X cha ng thi K2Cr2O7 1M , BaCl2 0,01M , SrCl2 0,1M . Tm khong pH cn thit lp vo
dung dch tch hon ton Ba2+ ra khi dung dch . Bit pT(BaCrO4) = 9,7 , pT(SrCrO4) = 4,4 v Cr2O72- + H2O
2CrO42- + 2H+ ; K = 10-14,6.
/s: 3,59 pH 3,88
Bi 103: (T770) C th ha tan 0,01mol AgCl trong 100ml dung dch NH3 1M khng ? Bit T(AgCl) = 1,8.10-10 ,
(Ag(NH3)2) = 108.
/s: Ha tan hon ton
Bi 105: (T13) Sc kh H2S vo dung dch X cha 0,005M v Co2+ 0,01M n khi dung dch bo ha H2S 0,1M . lng
Cd2+ trong dung dch cn 10% m CoS vn cha kt ta th pH ca dung dch X nm trong khong no? (Coi th tch
dung dch khng thay i ng k).Cho pka1(H2S) = 7,02 , pka2(H2S) = 12,90 ; pT(CoS) = 20,4 , pT(CdS) = 26
/s: -0,89 pH 1,26.
Bi 109: (T148) Cho dung dch cha Cl- 0,1M v CrO42- 10-4 M . Thm t t dung dch AgNO3 vo .Hi kt ta no xut
hin trc v khi kt ta th hai xut hin th t l nng gia Cl - v CrO42- l bao nhiu? C th dng Ag+ kt ta
phn on Cl- v CrO42- c hay khng? Bit khi nng t 10-6M tr xung th coi nh ion c tch ht.
Cho pT(AgCl) = 10 , pT(Ag2CrO4) = 12
/s: AgCl kt ta trc ; khi kt ta th 2 bt u xut hin th [Cl -]/[CrO42-] = 10-4 ; C th kt ta phn on c

Bi 116: (T70) Cho H2S li qua dung dch Cd2+ 0,01M v Zn2+ 0,01M n bo ha , nng H2S trong dung dch bo ha
l 0,1M . Thit lp vng pH m ti ch tn ti 0,1% Cd2+ trong dung dch m Zn2+ vn cha kt ta . Cho pka1(H2S) =
7,02 , pka2(H2S) = 12,90 ; pT(CdS) = 26 , pT(ZnS) = 21,6 ; lg(Cd(OH)+) = -10,2 , lg(Zn(OH)+) = -8,96.
/s: -0,04 < pH < 0,66
Bi 125: (T114) Dung dch A gm CrCl3 0,01M .Tnh pH bt u kt ta v kt ta hon ton Cr(OH) 3 t dung dch
( Coi mt ion c kt ta hon ton nu nng cn li ca ion trong dung dch khng qu 10 -6M ). Cho
pT(Cr(OH)3) = 29,8 ; lg*(Cr(OH)2+) = -5,92.
/s: Bt u kt ta khi pH = 4,75 ; Kt ta hon ton khi pH 7,2
Bi 126: (T126-127)
a, Tnh pH ca dung dch X gm Fe(NO3)3 , Co(NO3)3 , Bi(NO3)3 c cng nng 10-3 M. Bit lg*(Fe(OH)2+) = -2,17 ,
lg*(Co(OH)2+) = -1,78 , lg*(Bi(OH)2+) = -1,58.
b, Dung dch cha Ni2+ 0,04M v h m , gm NH3 v NH4Cl 0,5M ( pH dung dch bng 7 ). Hy cho bit c xut hin
kt ta Ni(OH)2 tch ra hay khng? Cho pT(Ni(OH)2) = 14,7 , lg[Ni(NH3)] = 2,72 , lg[Ni(NH3)2] = 4,89 , lg[Ni(NH3)3]
= 6,55 , lg[Ni(NH3)4] = 7,67 , lg[Ni(NH3)5] = 8,34 , lg[Ni(NH3)6] = 8,31 , lg*[Ni(OH)+] = -8,94.
/s: a, pH = 2,15 ; b, Khng xut hin kt ta Ni(OH)2.
Bi 127: (T133-134) Cho T(CaF2) = 3,4.10-11 v ka(HF) = 7,4.10-4.
a, Tnh tan ca CaF2 pH = 3,3
b, Nng HCl ban u t nht phi bng bao nhiu trong dung dch gm Ca(NO3)2 0,3M v NaF 0,1M khng c kt
ta CaF2.
/s: a, S = 2,88.10-4 M.

; b, C(HCl) = 7,08M

Bi 135: (T323) Trn 1ml dung dch m (A) gm NH3 2M v NH4NO3 2M vi 100ml dung dch B gm FeCl3 2.10-3M v
NaF 0,2M. Hi c kt ta Fe(OH)3 hay khng? Cho pT(Fe(OH)3) = 37 , lg(FeF2+) = 5,8 , lg(FeF2+) = 9,3 , lg(FeF2+) =
12,6
/s: C kt ta Fe(OH)3.