Tai-Lieu-Thuc-Hanh-Hoa-Phan-Tich

BI 1: NH TNH MT S ION ....................................................................................... 2 BI 5: XC INH CNG TRONG NC ................................................................. 4 1. L thuyt ................................................................................................................... 4 2. Dng c v thit b ................................................................................................... 4 3. Ha cht .................................................................................................................... 4 4. Tin hnh .................................................................................................................. 4 4.1. Pha dung dch ......................................................................................................... 4 4.2. Xc nh cng tm thi ...................................................................................... 5 4.3. Xc nh cng tng cng ................................................................................... 5 5. Cu hi chun b ........................................................................................................ 5 BI 4: XC NH HM LNG CANXI BNG PP KT TA OXALAT ...................... 6 1. Gii thiu .................................................................................................................. 6 2. Cc phng php xc nh canxi ............................................................................... 6 BI 6: NH LNG HM LNG NaCl TRONG NC MM ................................... 9 1. Nguyn tc phng php ........................................................................................... 9 2. Nhng iu kin chnh............................................................................................... 9 3. Dng c v ha cht ................................................................................................ 10 4. Qu trnh xc nh ................................................................................................... 10 BI 3. XC NH AXIT TRONG SA...................................................................... 12 1. Phm vi p dng ...................................................................................................... 12 2. Dng c ................................................................................................................... 12 3. Ho cht .................................................................................................................. 12 4.Tin hnh ................................................................................................................. 12

1 Su t m b i: www.daihoc.com.vn

BI 1: NH TNH MT S ION1. Th nghim 1: nh tnh ion NH4+ bng thuc th Nestler Cho vo ng nghim vi git dung dch NH4Cl 10 %; Thm 0,5ml NaOH 30%; Nh t t tng git thuc th Nestler; Quan st kt ta vng nu tch ra. Cho vo ng nghim vi git dung dch th Pb2+; Nh tng git Na2S 5%; Quan st kt ta xut hin.

2. Th nghim 2: nh tnh ion Pb2+ bng thuc th Sulfua -

3. Th nghim 3: nh tnh Borat bng thuc th Cucumins Cho vo ng nghim 5ml dung dch Na2B4O7 5%; Thm 10ml nc ct, lc u; Nhng giy ngh vng (giy c tm thuc th curcumin) vo ng nghim; kh t nhin trong t ht; Quan st ca giy, nu c mu hng xut hin, tc l c mt borat

4. Th nghim 4: nh tnh ion NO3- bng thuc th Diphenylamim Cho vo ng nghim 1ml dung dch Diphenylamine; Thm 5ml H2SO4 m c; Nh t t tng git dung dch NO3-; Quan st hin tng.

5. Th nghim 5: nh tnh Formaldehyde Cho vo ng nghim 3 ml dung dch thuc th; Thm 1ml Formaldehyde 1%; Pha long vi 5ml nc ct, un nng; Quan st hin tng. Cho vo ng nghim 3ml dung dch Cu 2+ 5%; Thm 1ml NH4OH 10%; Quan st hin tng.

6. Th nghim 6: nh tnh ion Cu2+ bng thuc th NH3 -


7. Th nghim 7: nh tnh ion Mn2+ bng thuc th K2S2O8 Cho vo ng nghim 1ml dung dch Mn2+ 1%; Thm 1ml K2S2O8 10%; 5 git dung dch Ag2SO4 20%; Pha long vi 3ml nc ct, un nng; Quan st hin tng.

Tr li cu hi: 1. Vit phn ng xy ra cho tng th nghim? 2. Gii thch hin tng xy ra? 3. Nu nh hng ca cc cht trong tng th nghim n sc khe con ngi?


BI 5: XC INH CNG TRONG NC1. L thuytTm hiu v cng ca nc: Ca2+, Mg2+ nh hng g n cht lng ca nc. Nc c cc ion ny s nh hng n h thng thit b dng trong sn xut v nh hng n cht lng thc phm nh th no? Nguyn l ca phng php kim: - cng tm thi: cng tm thi l s mdlgCanxi v Magie dng Bicacbonat c trong mt lt nc. Dng dung dch HCl tiu chun chun trc tip mu nc c cha cng cabonat (mu trc v sau khi un si) vi ch th MO. im tng ng nhn c khi dung dch chuyn t mu vng da cam sang mu hng nht. cng tm thi c tnh theo n v mg/l, 1mg/l tng ng vi 50mg CaCO3/l. - cng tng cng: cng tng cng c xc nh bng tng hm lng Canxi, Magie v c biu th bng mgCaCO3/l. Hm lng Ca2+ v Mg2+ trong nc c xc nh bng cch cho to phc vi EDTA pH 8-10, ch th ETOO (Eryochroma Black T). Ti im tng ng, dung dch chuyn t nho sang xanh dng. T th tch tiu tn ca EDTA, ta tnh c cng tng. Cc yu t nh hng ti kt qu: - Cc ion ha tr 2 v 3 c nh hng n qu trnh do co s to phc vi EDTA, nh Cu2+, Al3+, Fe3+... V vy cn loi b s c mt ca cc ion ny bng cch che. Che l mt qu trnh to phc bn y ngi ta cho cc ion kim loi ha tr 2 v 3 to phc vi KCN v NaF, trc khi chun EDTA.

2. Dng c v thit b3 becher 250mL 3 erlen 250mL 1 buret 25mL 1 phu, ng nh git 1 a thy tinh 1 cn phn tch 1 bp in, li amiang 1 pipet 25mL 1 pipet 10mL 1 bnh nh mc 100mL

3. Ha chtDung dch chun HCl 0.05N Dung dch chun HCl 0.01N Ch th MO 1% trong cn. 1,179 g EDTA.2H2O 7.8g MgSO4.7H2O 16.9 g NH4Cl 143mL NH3 Dung dch EDTA 0.01M. Giy lc bng xanh 1g Eriocrom black T 100g NaCl KCN 3% NaF 3%.

4. Tin hnh 4.1. Pha dung dchDung dch tiu chun EDTA 0.05N Dung dch m pH 10 gm: 1,179 g EDTA.2H2O + 7.8g MgSO4.7H2O + 50mL H2O + 16.9 g NH4Cl + 143mL NH3 . nh mc bng nc ct n 1000mL. Ch th ETOO: Cn 1g Eriochrom black T + 100g NaCl, nghin v trn u.


4.2. Xc nh cng tm thiLy chnh xc 100mL mu nc bng bnh nh mc, chuyn vo erlen 250mL Thm 3-4 git MO 1% em chun bng HCl 0.05N ti khi c s i mu ca dung dch t vng cam sang mu hng nht, ghi th tch ca HCl 0.05N tiu tn (V1 mL) Ly 250mL mu nc chuyn vo beaker 250mL loi chu nhit, un si mu nc 10 pht, ngui, lc qua giy lc bng xanh, dng nc ct trng ra cn trn giy v nh mc thnh 250mL, lc u. Ly chnh xc 100mL dung dch sau khi nh mc chuyn vo erlen 250mL, thm 3 4 git MO 1% v chun bng dung dch HCl 0.01N ti khi c s chuyn mu nh trn. Ghi th tch ca HCl 0.01N tiu tn (V2 mL). cng tm thi c tnh theo cng thc sau: C V C2 V2 cng tm thi (mdg/l) = 1 1 1000 Vm Trong : C1, V1 l nng v th tch HCl s dng chun mu trc khi un si. C2, V2 l nng v th tch HCl s dng chun mu sau khi un si. Vm: th tch mu chun (mL)

4.3. Xc nh cng tng cngDng pipet ly chnh xc 50mL mu cho vo erlen. Cho thm 5mL m pH =10; thm 5 git KCN 3% v 5 git NaF 3% v ht bp ETOO. Lc u Chun trc tip mu bng EDTA 0.05N n khi dung dch chuyn t mu nho sang mu xanh dng m (lm thm 2 mu na ly kt qu trung bnh). Ghi th tch EDTA s dng cng tng c tnh theo n v mg CaCO3/lt v theo cng thc sau: 1000 cng tng (mg CaCO3/lt) = md lg CaCO3.( NV ) . EDTA Vm Trong : VEDTA : Th tch ca dung dch EDTA NEDTA : Nng ca dung dch EDTA s dng (0.05N) Vm : Th tch mu chun (50mL) mdlg CaCO3 = 100/2 = 50mg

5. Cu hi chun bTrnh by tc ng ca Mg2 v Ca2+ i vi thc phm? Vit cc phng trnh phn ng xy ra? ngha ca cc phng php kim nghim trn trong thc t?


BI 4: XC NH HM LNG CANXI BNG PP KT TA OXALAT1. Gii thiuCanxi l nguyn t c nhiu nht trong c th ca chng ta, 98 99% canxi tp trung xng v rng, chim 1,6% trng lng ca mi ngi. Tc dng ca canxi i vi c th ngi: - Canxi l thnh phn chnh ca xng v rng. Cng vi phtpho v magi, canxi c vai tr hn gn nhng im xng b tn thng, bo qun xng, gip xng pht trin v gi c tnh cng, chc. - Khi c th khng c tip t canxi (do n ung thiu cht) cc tuyn ni tit s tit ra nhng hooc-mn c tc dng iu ng cht canxi ca xng tan vo mu, khin cho t l canxi trong mu khng gim, nhng lm cho xng yu v d gy. - Canxi cn c lin quan ti cc hin tng co c, nhp p ca tim, s ng c ca mu, vic tch cc acid bo ra khi mng t bo. T l canxi mng t bo, trong t bo, hay nhn t bo c nh hng quyt nh ti nng lng ca t bo. - C th tha hay thiu canxi u khng tt cho sc khe con ngi. Nhng ngi b thiu canxi thng gy m, xanh xao, mu chm ng. - Khi lng canxi trong mu thp qu mc bnh thng, tuyn thng thn s tit ra mt hoc-mn iu ng lng canxi ca xng vo mu. Nu hin tng ny ko di, xng s b yu i v d gy khi b va chm trong cc tai nn hoc vp ng nh. Nhiu nh khoa hc cn cho rng hn tng thiu canxi cn c lin quan c ti bnh cao huyt p v ung th i trng. - Vic hp thu canxi ca c th cn c s kch thch v nh hng canxi ho nhp vi cc t bo xng, trnh hin tng ng cn ti cc c quan ni tng gy ra cc bnh si, bnh tim mch nn khi dng thuc b sung thm canxi cho ngi bnh ngi ta thng dng thm cc thuc khc nh: vitamin D, vitamin B6, vitamin C, magi v km.

2. Cc phng php xc nh canxiC hai phng php xc nh canxi: Phng php nh lng di dng oxalate v phng php nh lng bng Complexon III

2.1. Phng php nh lng bng Complexon IIINguyn l: axit etylen diamin tetraxelic (trilon B) vit tt l EDTA c kh nng to thnh nhng phc cht vi nhiu cation, c bit vi Ca, Mg. Axit etylen diamin tetraxelic (trilon B) hoc mui natri ca n mi trng kim, cho vi canxi mt phc cht bn vng m amoni oxalat cng khng ph hy ly Ca cho ta c. Ch vi ch th mu c bit mi pht hin s c mt ca Ca2+, Mg2+, th d: Eriocrom den T cho mu khi c Ca2+, Mg2+ t do, v mu l khi nhng ion y dng phc cht. Murexid cho mu khi c Ca2+ t do v mu l khi ion y dng phc cht. Phng php ny c chnh xc khng cao do EDTA kt ta khng chn lc. Do khi kim tra hm lng canxi trong thc n gia sc ngi ta dng phng php nh lng di dng oxalat.


2.2. Phng php nh lng di dng oxalatc trng ca phng php pemanganat xc nh canxi: Hm lng Canxi s c xc nh thng qua qu trnh chun ion oxalat, c ha tan t kt ta canxioxalat vi thuc th pemanganat theo k thut chun thay th. Ngi ta cho vo dung dch canxi cn phn tch mt thuc th nh amoni oxalat. Khi c mt lng tng ng kt ta canxi oxalat bng pemanganat. Bit lng oxalat c th d dng tnh c hm lng canxi. Nguyn l: Sau khi v c ho thc phm, kt ta canxi di dng canxi oxalat. Lc, ra kt ta v nh lng bng KMnO4 mi trng H2SO4. Phn ng xy ra nh sau: Ca2+ + H2C2O4 CaC2O4 + 2H+ CaC2O4 + H2SO4 CaSO4 + H2C2O4 5H2C2O4 + 2KMnO4 + 4H2SO4 2MnSO4 + K2SO4 + 10CO2 + 8H20 Dng c, thit b v ho cht - L nung iu chnh nhit n 6000C - Cn phn tch chnh xc n 0.0001g - Bnh nh mc dung tch 250 mL - Cc dung tch 250 mL - Chn nung - a thu tinh - Dung dch H2SO4 m c - Dung dch HCl (1+3) - Dung dch (NH4)2C2O4 bo ha (4.2%) - Dung dch NH4OH (1+ 50) - KMnO4 0.1N - Ch th metyl red: ha tan 1g metyl red trong 100 mL metanol Tin hnh th Tin hnh th nghim hai ln cho mi mu th theo cc bc sau: - Cn khong 2.5 g mu ( c trn v nghin mn) chnh xc n 0.0001g vo chn nung. - Nung nhit 6000C trong 2 gi. Ly chn ra ngui - Thm 40 mL HCl (1+3) v vi git HNO3. un si. - Chuyn ton b mu trong chn vo bnh nh mc 250 mL, ngui. nh mc n vch. - Lc u v lc. - Tu lng canxi d on c trong mu ly 1 th tch dch lc ph hp vo cc dung tch 250 mL.Thm nc n khong va 100 mL.Thm 2 git ch th metyl red. - Thm tip dung dch NH4OH tng git cho n pH = 5,6 (dung dch c mu cam nu nht) - Khi c lng tha NH4OH thm tip dung dch HCl (1 + 3) cho n khi dung dch c mu hng. Thm 4 git HCl (1+3) tha, mu phi c mu hng nht, khng c mu cam. - Pha long dung dch mu n khong 150 mL. un si. - Thm tht chm (va thm va khuy u) dung dch (NH4)2C2O2 bo ha (nu mu chuyn thnh cam hoc vng th thm tng git HCl (1+3) cho n khi mu chuyn thnh hng nht. - qua m hoc cho kt ta hon ton - Lc qua giy lc nh lng - Dng nc nng ra kt ta, n khi nc ra khng cn ion Cl-.


- c thng giy lc ri ra giy lc bng hn hp 125 mL nc v 5 mL H2SO4 - Hng tt c cc dch ra vo cc - un n 700C - Chun dung dch bng mu KMnO4 0.1N n mu hng nht (thm giy lc vo tip tc chun nu cn). - Thc hin mu trng vi lng thuc th v trnh t nh trn nhng thay mu th bng nc ct Tnh kt qu Hm lng canxi c tnh theo cng thc: V VB * N * k * 2 X S M Trong : N: Nng dung dch KMnO4, N VB: Th tch dung dch KMnO4 chun mu trng, mL VS: Th tch dung dch KMnO4 chun mu th, mL k: H s pha long M: Khi lng mu, g X: Hm lng Canxi, % Ch thch: - Nu thc phm cha nhiu canxi, dng KMnO4 0.1N. Nu thc phm cha t canxi, dng KMnO4 0.05N hay 0.02N. - Nu t kt ta c th ra kt ta theo cch ly tm (ly tm, gn nc trong pha trn, cho nc vo ra cn ri li ly tm). - Nu c nhiu kt ta c th cho thm mt t axit pecloric long ha tan trc khi chun . - Nn trnh thng H2SO4 20% ln giy lc v CaSO4 hnh thnh s mau chng lm mng bao bc kt ta, kt ta pha trong khng ho tan c v nh lng s sai s thiu. Kt qu c th sai s do: - Do thao tc - Khi ra ta canxi, cha ra ht ion Cl- Do chun


BI 6: NH LNG HM LNG NACL TRONG NC MMTrong mui n, thnh phn ch yu l NaCl chim 89-90 %, mt lng tp cht khng tan v mt lng nh mui CaCl2, MgCl2, thng dng phng php Mohn nh lng cc mui Clorua trong mui n 1. Nguyn tc phng php Da trn c s ca phng php chun kt ta, dng dung dch AgNO3 tiu chun trc tip xung mu mui n c cha Cl-, phn ng thc hin trong mi trng trung tnh (pH = 6,5 7,2). AgNO3 + NaCl = AgCl + NaNO3 Nhn bit im tng ng bng ch th K2CrO4, khi c xut hin kt ta gch: 2AgNO3 + K2CrO4 = Ag2CrO4 + 2KNO3 %Clo = mdlg Cl.(NV)AgNO3.Vdm 100 . Vxd mbd

Vi mdlg Cl = 0,0355 gam

2. Nhng iu kin chnh a- Ha tan mu bng nc ct nng, cn lc b tp cht khng tan. b- iu kin mi trng chun : Chun trong mi trng st trung tnh (pH = 6-5 7,2) vn m bo AgCl hnh thnh hon ton trc, ti im tng ng, Ag2CrO4 hnh thnh r rt, t gy sai s. Nu mi trng axit th Ag2CrO4 d tan, nhy ca ch th gim. Cn mi trng kim s tiu tn AgNO3 nhiu do sinh ra AgOH v AgOH thy phn thnh Ag2O kt ta en, kt qu chun s sai c- Liu lng v nng ch th Theo tnh ton mi ln chun vi 25ml dung dch, cn cho 4 5 git K2CrO4 5% l thch hp, t gy sai s.


Nu liu lng ch th nhiu hn, ti im tng ng mu vng dung dch s m, nh hng vic nhn kt ta gch thng dn n vic nhn im tng ng sm hn. Nu liu lng ch th t, nhn bit tng ng kh, cng gy sai s. 3. Dng c v ha cht 3.1. Ha cht Mu mui n Dung dch AgNO3 0,05N Ch th K2CrO4 5% Dng c a thy tinh

3.2. -

- 3 erlen 250 ml - 3 cc 250 ml Buret 25 ml Bp cao su

- 2 Pipet 10 ml 4. Qu trnh xc nh 1. Thit lp nng cho dung dch AgNO3 0,05N Sinh vin tnh cn chnh xc mt lng cn KCl pha 250 ml KCl 0,05N dng thit lp nng cho dung dch AgNO3 0,05N Ht chnh xc 10-25 ml dung dch KCl va pha, chuyn vo bnh nn 250ml, thm 4 5 git ch th K2CrO4 5%, un si ri chun dung dch bng AgNO3 0,05N ti khi xut hin kt ta gch Ag2CrO4 Cn th nghim 3 ln, sai lch gia ba ln chun 0,1mlNAgNO3 ( NV ) KCl VAgNO3

2. Qu trnh xc nh Cn chnh xc 1,0 0,0002g mu mui n ( uc sy k 105 0C khong 2 gi, lun bo qun trong bnh ht m, c nghin mn). Ha tan bng nc ct


nng, lc qua giy lc dy (loi tp cht khng tan), dng nc ct trng ra sch giy lc, ngui v nh mc thnh 250ml dung dch. Lc trn u. Ht chnh xc 10-25 ml dung dch, chuyn vo bnh nn 150 250ml, thm 4 5 git ch th K2CrO4 5%, un si ri chun dung dch bng AgNO3 0,05N ti khi xut hin kt ta gch Ag2CrO4 Cn th nghim 3 ln, sai lch gia ba ln chun 0,1ml. Kt qu c tnh nh cng thc ghi 5. Cu hi 1. 2. 3. 4. Trnh by c s ca phng php Mohn? Phng php xc nh b nh hng bi ion no ? So snh vi phng php Vohlhard? Ti sao phi un si trc khi chun ?


BI 3. XC NH AXIT TRONG SA1. Phm vi p dngp dng kim tra sa ti nguyn liu v thnh phm

2. Dng cPipet 10 mL c vch chia 0,1 mL. Pipet hay Buret 10 25 mL c vch chia 0,1 mL. Cc thu tinh 250 mL

3. Ho chtDung dch Phenolphtalin 1%. Dung dch NaOH 0,1 N

4.Tin hnh Xc nh theo n v % acid lactic: Trn u mu, dng Pipet chuyn 17,6 mL sa ti vo cc thu tinh. Thm vo 3 5 git dung dch Phenolphtalein, lc u. nh phn vi dung dch NaOH 0,1 N cho n khi dung dch xut hin mu hng nht bn trong 30 giy. c th tch dung dch NaOH 0,1N tiu tn, mL Hm lng acid trong sa ti (% acid lactid) c tnh thheo cng thc: % Acid = V/20 Xc nh theo n v T: Trn u mu, dng Pipet chuyn 10 mL sa ti vo cc thu tinh. Thm vo 3 5 git dung dch Phenolphtalein, lc u. nh phn vi dung dch NaOH 0,1N cho n khi dung dch xut hin mu hng nht bn trong 30 giy. c th tch dung dch NaOH 0,1N tiu tn, mL Hm lng acid trong sa ti ( T) c tnh theo cng thc: 0T = 10.V


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Tai-Lieu-Thuc-Hanh-Hoa-Phan-Tich