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KHOA CNG NGH HA HC

BI TP LN

MN:

GVHD: Ths. Trn Nguyn An Sa SVTH: L Th M Vn MSSV: 09078531

Thnh ph H Ch Minh, ngy 14 thng 5 nm 2012

Cu 1: Theo h thng phn tch acid bazo, cation c chia thnh 6 nhm: Nhm 1 gm Ag+, Hg2+, Pb2+. Cc clorua ca nhm ny khng tan trong nc v trong cc acid long. Thuc th nhm l HCl 2N. Nhm 2 gm Ba2+, Sr2+, Ca2+. Sulfat ca chng khng tan trong nc v cc dung dch acid. Thuc th ca nhm l H2SO4 2N. Nhm 3 gm Al3+, Cr3+, Zn2+, As3+, As5+, Sb3+, Sn2+, Sn4+. Cc hydroxyt ca chng u lng tnh tan trong dung dch km d. Thuc th thng dng l NaOH 4N v KOH 4N d. Nhm 4 gm Mg2+, Mn2+, Fe2+, Fe3+, Bi3+, Sb5+, Sb3+. Cc hydroxyt ca chng u khng tan trong dung dch km d. Thuc th thng dng l dung dch NH3 25% d. Nhm 5 gm Cu2+, Cd2+, Hg2+, Co2+, Ni2+. Cc hydroxyt ca chng to ra cc amoniacat tan. Thuc th l dung dch NH3 25% d. Nhm 6 gm cc cation kim loi km v NH4+. Cc clorua, sulfat v hydroxit ca chng u c th tan trong nc. Chng khng c thuc th nhm. Cc hp cht c mt nhm ny u c th tan to thnh dung dch.

Cu 2: Theo h thng phn tch acid bazo, anion c chia thnh 3 nhm: Nhm I: Cl-, Br-, I-, SCN-, S2O32Nhm II: SO42-, HCO3-, CO32-, PO43Nhm III: NO3-, NO2-, CH3COO-.

Cu 3: Thuc th nhm l nhng thuc th c phn ng cng mt kiu vi mt nhm ion, nhng khng phn ng vi cc ion khc nhm. Nh vo cc thuc th nhm, ngi ta tch c tng nhm ion ra khi hn hp nhiu ion.

Vd: axit clohiric (HCl) l TTN cho nhm cc ion Ag+, Pb2+, Hg2+; H2SO4 l TTN cho nhm cc ion Ba2+, Sr2+, Ca2+, Nhm 1:( Ag+, Hg2+, Pb2+) c thuc th chung l HCl 2N. Phn ng to cc hp cht kt ta kh tan trong nc v trong cc acid long. Ag+ + Cl-

AgCl (trng, tan trong dung dch NH3) [Ag(NH3)2]Cl (phc cht tan)

AgCl + 2NH3

Pb2 2Cl PbCl2 (trng, khng tan trong dd NH3 nhng tan trong nc

nng) Hg 2 2Cl Hg 2Cl2 (trng, chuyn sang xm en trong dd NH3)

Kt ta Hg 2Cl2 tan trong dd NH3:Hg2Cl2 2NH3 [Hg 2 NH2 ]Cl+NH4Cl

Sau dimecuua amoni clorua khng bn li t phn hu thnh mecua amoni t tan v thu ngn kim loi lm cho kt tu c mu xm en[Hg 2 NH2 ]Cl [HgNH2 ]Cl Hg (xm en)

Nhm2: (Ba2+, Sr2+, Ca2+) c thuc th chung l H2SO4 long, phn ng to cc kt ta sulfat mu trng khng tan trong cc acid v kim. Ba 2+ +H2SO4 BaSO4 +2H+

Sr 2+ +H2SO4 SrSO4 +2H+Ca 2+ +H2SO4 CaSO4 +2H+

Nhm3: (Al3+, Cr3+, Zn2+) l nhng cation tng ng vi nhng kim loi lng tnh, khi tc dng vi dd kim to nhng hydroxyt lng tnh kt ta, tan trong dd kim c d. Thuc th nhm l dd KOH hay NaOH d. Thm t t tng git dd kim long vo dd mui ca cation nhm 3, kt ta keo hydroxyt c to thnh: Al3+ +3OH Al(OH)3 (mu trng, v nh hnh)

Zn 2+ +2OH Zn(OH)2 (mu trng)

Cu 4:

Cr 3+ +3OH Cr(OH)3 (mu lc xm)

Thuc th c trng l thuc th c tnh c hiu i vi mt loi ion nht nh, to

nn nhng phn ng c trng nhn bit s c mt ca ion trong hn hp cht. Phn ng c trng: l phn ng m nh chng, trong nhng iu kin xc nh ca phng th nghim c th xc nh c ion duy nht trong dung dch, khi ang c s hin din ca nhng ion khc pht hin c nh vo: + Xut hin mu sc c trng. + C s kt ta. + C s gii phng kh Thuc th c trng ca mt s ion: a. Ag+ Dng thuc th dung dch NaOH: to kt ta Ag2O mu en, kt ta ny tan trong dd NH3, to ph amoniacat [Ag(NH4)2]+ 2Ag+ + OHAg2O + 2NH4+ nc nng. 2Ag+ + SO42dd NH3. Ag2SO4 Dng thuc th dd KI to kt ta vng nht AgI, kt ta ny khng tan trong Ag2O + H+ 2[Ag(NH4)2]+

Dng thuc th dung dch H2SO4: to kt ta Ag2SO4, kt ta ny tan trong

Ag + +I AgI b. Pb2+ Dng thuc th dung dch H2SO4 long: to kt ta trng PbSO4, kt ta ny b tan trong dung dch H2SO4 m c. Pb2+ + SO42PbSO4

-

Dng thuc th KI: to kt ta vng ng nh, kt ta ny cho vo dung dch CH3COOH long un nng, ri lm lnh, c tinh th hong kim (cn gi l phn ng ma vng).Pb2+ +2KI PbI2 +2K +

Kt ta PbI2 tan nhiu trong nc nng, khi lm lnh th dd xut hin li kt ta PbI2 tinh th mu vng ng nh. Dng thuc th (NH4)2S: to kt ta en khng tan trong NH3 d Pb2+ + S2c. Ba2+ Dng thuc th dung dch K2CrO4: to kt ta mu vng BaCrO4. Kt ta ny khng tan trong dd NaOH v CH3COOH. PbS mu en

Ba 2 K 2CrO4 BaCrO4 2K Dng thuc th Wohlers: trong mi trng KMnO4, ion Ba+ tc dng vi dd H2SO4 2M to kt ta BaSO4 mu trng. Tuy nhin thc t ch thy kt ta mu tm hng trong dd. l do kt ta c tnh hp th mu ca dd KMnO4. Sau dng H2O2 kh mu tm ca dung dch KMnO4 th mu hng ca BaSO4 hp th vn gi nguyn. 5H2O2 + 2KMnO4 + 3H2SO4 = K2SO4 + 2MnSO4 + 8H2O + 5O2 (dung dch mt mu hng) d. Ca2+ Dng thuc th (NH4)2C2O4 to kt ta mu trng CaC2O4. Kt ta ny khng tan trong dung dch CH3COOH Ca2+ + (NH4)2C2O4 e. Sr2+ Dng thuc th (NH4)2C2O4 cho kt ta oxalate mu trng tinh th, kt ta tan c trong dd CH3COOH Sr2+ + (NH4)2C2O4 SrC2O4 + 2H+ SrC2O4 + 2NH4+ Sr2+ + H2C2O4 CaC2O4 + 2NH4+

-

Dng thuc th K2CrO4: to kt ta tinh th mu vng SrCrO4 tan trong mi trng acid yu nh dd CH3COOH (BaCrO4 khng tan trong mi trng ny) Sr2+ + CrO42SrCrO4

Bng tm tt cc cation nhm 1, 2, 3 1. Cation nhm 1: Ag+, Pb2+ : thuc th nhm l dd HCl 2N Cation Ag+ Thuc th HCl-

Hin tng PTP Kt ta trng AgCl tan trong dd NH3 Ag+ + Cl AgCl [Ag(NH3)2]Cl

AgCl + 2NH3

KI hay KBr

To kt ta tinh th mu vng

Ag + +I AgI Ag + +Br AgBr (mu vng nht)NaOH hay KOH To kt ta AgOH mu trng nhng khng bn, phn hy nhanh to thnh kt ta Ag2O mu enAg + +OH AgOH 2AgOH Ag2O +H2O

Dung dch NH3

To kt ta Ag2O en, ta tan trong dung dch NH3 d 2Ag+ +2NH4OH Ag 2O +NH4 +H2O

Ag2O + 2NH4+ Na2CO3 K2CO3

2[Ag(NH4)2]+

hay To kt ta Ag2CO32+ 2Ag + +CO3 Ag2CO3

K2CrO4 trong mi To kt ta mu nu trng trung tnh Dung dch H2S2Ag+ +CrO2- Ag2CrO4 4

To kt ta en tan trong dd HNO3 long nng2Ag + +S2- Ag 2S 3Ag2S+2NO3 +8H+ 6Ag+ +2NO+3S+H2O

Na2HPO4

To kt ta mu trng tan trong dd HNO3 v dd NH33Ag + +HPO2- Ag3PO4 4

Ag3PO4 +6NH4OH 3[Ag(NH3 )2 ]+ +PO3- +6H2O 4

Pb2+

HCl

To kt ta trng khng tan trong dung dch NH3 nhng tan trong nc nng Pb2+ + 2Cl-

PbCl2

KI

To kt ta vng ng nh, kt ta ny cho vo dung dch CH3COOH long un nng, ri lm lnh, khi lm lnh th dd xut hin li kt ta PbI2 tinh th mu vng ng nh.Pb2+ +2KI PbI2 +2K +

Dung dch H2S

To kt ta en khng tan trong NH3 d Pb2+ + S2PbS mu en

K2CrO4

To kt ta mu vng thm. Kt ta ny tan trong dd HNO3 long v NaOH Pb2+ + CrO42PbCrO4 + 2H+ PbCrO4 + 4OHPbCrO4 Pb2+ + H2CrO4 PbO22- + CrO42- + 2H2O

H2SO4 long hay To kt ta tinh th trng mui sulfat dd KOH Pb2++SO42- PbSO4 hay To kt ta trng tan trong dd thuc th d Pb2+ + 2OH- Pb(OH)2 Pb(OH)2 + 2OHDung dch NH3 PbO22- + 2H2O Pb(OH)2 + NH4NO3 Pb2(OH)2CO3 To kt ta bazo khng tan trong thuc th d Pb(NO3)2 + NH4OH Na2CO3 K2CO3 Na2S2O3 2Pb2+ + CO32- + 2OH-

NaOH

hay To kt ta ch cacbonat bazo To kt ta mu trng tan trong thuc th d to phc v phc ny cng b acid phn hy khi dun nng Pb2+ + S2O32- PbS2O3

PbS2O3 + 2 S2O32[Pb(S2O3)3]4-+2H+ Na2HPO4

[Pb(S2O3)3]4PbS+2S+2SO2+SO42-+H2O

To kt ta mu trng tan trong NH4OH 3Pb2+ + 2HPO42- Pb3(PO4)2 + 2H+ Pb3(PO4)2 + 9OH- 3HPbO2- + 2PO43- + 3H2O

2. Cation nhm 2: Ba2+, Cu2+, Sr2+ Thuc th nhm: dd H2SO4 Cation Ba2+ Thuc th H2SO4 sulfat Na2CO3 v Hin tng PTP

mui To kt ta trng khng tan trong acid v kim Ba2+ + SO42BaSO4 To kt ta mu trng tinh th t tan trong nc nhng tan trong cc acid HCl, HNO3, Ba2+ + CO32BaCO3 + 2H+ BaCO3 Ba2+ + H2O + CO2

K2CrO4

To ta tinh th mu vng, t tan trong nc v dd CH3COOH Ba2+ + CrO42BaCrO4

(NH4)2C2O4

To kt ta oxalate tinh th mu trng tan trong cc acid HCl, HNO3 Ba2+ + C2O42BaC2O4 + 2H+ BaC2O4 Br2+ + H2C2O4

Na2HPO4

To kt ta trng tan trong cc acid HCl, HNO3, CH3COOH Ba2+ + HPO42BaHPO4

NaOH hay KOH To kt ta trng c Ca2+ Ba2+ + OH- Ba(OH)2 Ca2+ + SO42CaSO4

dd H2SO4 long v To kt ta trng khng tan trong acid v trong kim cc dd mui sulfat

Na2CO3

To kt ta tinh th mu trng tan trong cc acid HCl, HNO3 v CH3COOH Ca2+ + CO32CaCO3 + 2H+ CaCO3 Ca2+ + H2O + CO2

(NH4)2C2O4

To kt ta mu trng, kt ta ny khng tan trong dung dch CH3COOH Ca2+ + (NH4)2C2O4 CaC2O4 + 2NH4+

Na2HPO4

To kt ta trng tan trong cc acid HCl, HNO3, CH3COOH Ca2+ + HPO42CaHPO4 SrSO4

Sr2+

dd H2SO4 long v To kt ta trng khng tan trong acid v trong kim cc dd mui sulfat Na2CO3 Sr2++ SO42-

To kt ta tinh th mu trng tan trong cc acid HCl, HNO3 v CH3COOH Sr2++ CO32SrCO3 + 2H+ SrCO3 Sr2+ + H2O + CO2

(NH4)2C2O4

To kt ta oxalate mu trng tinh th, kt ta tan c trong dd CH3COOH Sr2+ + (NH4)2C2O4 SrC2O4 + 2H+ SrC2O4 + 2NH4+ Sr2+ + H2C2O4

K2CrO4

To kt ta tinh th mu vng SrCrO4 tan trong mi trng acid yu nh dd CH3COOH Sr2+ + CrO42SrCrO4

3. Cation nhm 3: Al3+, Zn2+, Cr3+. Thuc th nhm: dd NaOH hay KOH Cation Al3+ Thuc th dd NaOH KOH Hin tng PTP hay Kt ta hydroxit v nh hnh c to thnh v ta tan khi dd thuc th d, v dd acid Al3+ + 3OHAl(OH)3

Al(OH)3 + NaOH

NaAlO2 + 2H2O

Al(OH)3 + 3HCl AlCl3 + 3H2O dd NH3 To kt ta trng tan c trong thuc th d v dd acid Al3+ + 3NH4OH Al(OH)3 + NH4OH Al(OH)3 + 3NH4+ NH4AlO2 + H2O

Al(OH)3 + 3HCl AlCl3 + 3H2O Na2HPO4 dd nc H2S To thnh mui photphat kh tan mu trng Al3+ + 2Na2HPO4 AlPO4 + 3Na+ + NaH2PO4 Trong mi trng trung tnh hoc amoniac to thnh kt ta trng 2NH4OH + H2S 2Al3+ + 3(NH4)2S Al2S3 + 6H2O (NH4)2S + H2O Al2S3 + 6NH4+ 2Al(OH)3 + 3H2S

Aluminon trong To kt ta l phc ni mu hng m mi trng CH3COOH hoc dd m acetac dd (NH3+NH4Cl) To kt ta trng keo tan trong dd acid hay bazo, nhng khng tan trong dd NH3 v dd mui amoni dd Alizarin v cc dn xut ca n trong mi trng NH4OH 8 oxiquinolin trong mi trng m acetac dd NaOH hay KOH To mui phc mu dng kt ta hay dung dch

Kt ta tinh th mu vng lc Al3+ + 3C9H6N(OH) (C9H6NO)3Al + 3H+ Kt ta hydroxit c to thnh v ta tan khi dd thuc th d, v dd acid Zn2+ + 2OHZn(OH)2 Na2ZnO2 + 2H2O

Zn(OH)2 + 2NaOH

Zn(OH)2 + 2HCl ZnCl2 + 2H2O dd NH3 To kt ta trng tan c trong thuc th d v dd acid

Zn2+

Zn2+ +