phuong phap chuan do ket tua 9234

Download Phuong Phap Chuan Do Ket Tua 9234

Post on 01-Jan-2016

91 views

Category:

Documents

4 download

Embed Size (px)

TRANSCRIPT

  • Phng php chun kt taGing vin hng dn: Dng Th Lan

    Nhm sinh vin thc hin:Phng php mohrNguyn Th TuytNguyn Th Thyo Th BchNguyn Th HnhTrn Vn TuynNguyn Th Hng LanLp C9KM2

  • Phng php xc nh im dng trong chun o bc

    Nguyn tc:

    Chun kt ta l phng php th tchda trn c s ca cc phn ng to cht kt ta t tan

  • Phng php xc nh im dng trong chun o bc Yu cu ca phn ng chun : + Phn ng xy ra ng phng trnh, khng c phn ng ph. + Phn ng xy ra nhanh, nhy, chn lc. + To kt ta khng tan. + Chn c ch th thch hp

  • Phng php Mohr Mc ch :

    - Xc nh im dng trong chun o bc. -Xc nh Cl- ; Br - ;khng xc nh c I- , SCN-

    Nguyn tc :

    Xc nh cc halogenua bng dung dch Ag+ vi cht ch th l CrO42-

  • Phng php Mohr Ch th : CrO4 2- Phng trnh phn ng chun : Ag+ + X - AgX Ti st im tng ng c phn ng : 2 Ag+ + CrO4 2- Ag2CrO4 ( gch)

  • Phng php Mohr iu kin chun : - Phi tin hnh trong mi trng trung tnh hoc baz yu V : + pH thp, ion CrO42- gim nng do tc dng vi ion H+ nn kt ta gch khng xut hin st im tng ng 2CrO42- + 2H+ 2CrO72- + H2O + pH cao, Ag+ b thy phn, s xut hin Ag2O kt ta en

    2Ag+ + 2OH- 2AgOH Ag2O + H2O (rn) (rn, en) -Nng ca cht ch th phi m bo cho kt ta ca ch th vi bc xut hin st im tng ng

  • Phng php Mohr Dng c: pipet, buret, bnh nh mc, bnh tam gic sch, cn k thutS chun :

  • Phng php Mohrtin hnh

  • Phng php Mohr c, kt qu: CX- = (CAg+ . VAg+) / VX-

    Gii thch lng dng ca ch th:

    2Ag+ + CrO42- Ag2CrO4

    ( gch)

  • Phng php Mohr V mt l thuyt, sai s bng khng, kt ta gch phi xut hin ti thi im tng ng, khi ; Ks(AgCl) = 10-10 (M)V dung dch bo ha:[Ag+][Cl-] = 10-10 (M) [Ag+] = [Cl-] = 10-5 (M) Gi tan ca CrO42- l s

  • Phng php Mohr s = =2. = 0,02 (M)

    = 0.02M th lm cho Ag+ s b thy phn xut hin kt ta en Ag2O cn gim nng ca ch th xung + ) c ch th st im tng [CrO42-]= 0.005(M) [Ag+]= = = 2.10-5pAg = - =4,7Lc sai s mc phi l: +o,1 % nn chp nhn c.

  • Phng php Mohr Xt trng hp c th : chun clorua bng phng php mohr 1. Nguyn tc: -phn ng chun : Ag+ + Cl- AgCl (trng) St im tng ng :

    2Ag+ + CrO42- Ag2CrO4 ( gch) -pH tng ng:

    - Cht ch th : CrO42-

  • Phng php Mohr2. Ha cht- dng c:

    * Ha cht:

    - Cht chun : Ag + (AgNO3)

    - Cht nh phn : Cl (NaCl)

    - Ch th : CrO42- 5% (K2CrO4)

  • Phng php Mohr- Tnh ton pha cht nh phn v cht chun: 100 ml , 0,1N mAgNO3 = V.C.M = 0,1.0,1.170 = 1,7(g) mNaCl =V.C.M = 0,1.0,1.58,5 = o,585(g) + Cn chnh xc 1,7 g AgNO3 ha tan trong 100ml nc ct + Cn chnh xc 0,585 g NaCl ha tan trong 100ml nc ct + Dng pipet ly chnh xc 5 g K2CrO4 ha tan trong 100ml nc ct

  • Phng php MohrDng c: pipet, buret bnh nh mc, bnh tam gic, cn k thut3. Tin hnh th nghim:+ S chun

  • Phng php Mohr tin hnh:

  • Phng php Mohr4. Kt qu:

    CN(Cl-) = (CN(Ag+).VAg+) / VCl- CM(Cl-) = CN(Cl-)

  • The end.