1. PHM VI 1.1 Phng php ny c dng xc nh mnh tng i ca dung mi hydrocarbon dng trong cng thc sn v sn mi. phng php ph hp s dng vi cc dung mi c im si ban u hn 40 C v mt im kh di 300 C, c xc nh bi IS: 1448 [P: 18 l-1967 *.2. Thut ng

2.0. Mc ch ca phng php ny, cc nh ngha sau y s c p dng

2.1. Gi tr kauri butanol

Th tch (ml) dung mi a vo 25oC, t n mt tiu chun c xc nh r. Cn thit nh r mc c khi thm vo 20g dung dch chun ca nha trong ru butyl . Cho cc gi tr Kauri butanol l 60 tr ln, tiu chun l toluen v mt gi tr c gn l 105. i vi cc gi tr kauri butanol di 60, tiu chun ny l mt s pha trn ca 75% n-heptan v 25% toluen, v gi tr p t l 403. S lc v phng php

3.1. Trong phng php ny, cho 20g dung dch chun ca nha thng vo ru butylic iu kin bnh thng chun vi dung mi c th nghim cho n khi ch ra nhng nt chnh ca 10 im bn in c t trc tip di ni un cch thy hoc trc tip bn di bnh khi quan st qua dung dch kt qu ca nha thng b ti hoc lm nhe, nhng khng kh c.4. Dng c

4.1. Ni un cch thy : cc cha thy tinh, duy tr 251oC ; cch khc, c th s dng phng duy tr 25 1C . - Cc 200 ml

- Bnh tam gic : 250 ml

- Buret : 50ml

4.5. Mu in:Mu in - tm trng giy c trn en 10 trn 12 im in, i din duy nht Baskerville ; mu trong 10 trn 12 im in c trao cho bn di :Th tch ml ca dung mi 25oC, mt tiu chun c xc nh c khi thm 20g dung dch tiu chun ca nha kauri trong ru butyl. Cho cc gi tr kauri butanol 60 tr ln, tiu chun l toluen v c mt gi tr c gn l 105. i vi cc gi tr kauri butanol di 60, tiu chun l s pha trn ca 75% n-heptan v 25% toluene, v c mt gi tr c gn l 40.5. Ha cht

5.1. Phng php Kauri butanol

Lm sch 400g trong bnh 3 lt,nht mu, nha thng ca lp XXXX, XXX hoc XX mt t khong c bng ht u hoc nh hn. Thm mt cht kch thch mnh, 2000g ru n- butyl ca khong si 116 118oC (xem IS: 361-1962t). Cho vo my rung lc cho n khi nha ha tan vo dung dch, nng nhit ln 55oC, nu cn ha tan vo dung dch. Nu my rung khng c sn th iu chnh cho bnh va vi b ngng t dng ngc v nhit a vo cho n khi nha c ha tan. dung dch 48h, ri lm sch bng cch lc qua phu, s dng giy lc kp v thay i thng xuyn khi cn thit.5.2. Toluen : Dng lm tiu chun ha tan cao, nitro ha ( xem IS: 537 1967).

5.3. Hn hp Heptan- Toluen :Bao gm 250.1 % toluen v 75 0.1 % n-heptane, c s dng nh mt kh nng ha tan thp. Cc heptan (nh gi th) phi ph hp vi cc yu cu sau:c trngYu cu

Mt 20oC, g/ml0,683 0,684

Nhit phc hi 50oC98,40 98,450C

Phn trm phc hi nhit t 20 n 80oC, Max0,200C

im ng c, Min90,720C

Ch s octan0,00,2

Ch s khc x, 20oC1,3876 1,3878

5.3.1. S pha trn ca 250.1% toluene v 750.1% heptan c th c chun b bng cch no s cho chnh xc mong mun. Cc k thut sau y l :

Mang theo toluene tinh khit v heptan tinh khit v hiu chun 200 ml

bnh nh mc cng mt nhit tt nht l mt hng s nhit phng hoc nhit. Chy 50 ml toluen vo Bnh nh mc 200 ml, s dng mt buret hoc hiu chun pipette cung cp 50 ml toluen nhit la chn (tt nht l 25 C). in

bnh nh mc nh di mc chun vi n-heptan, chn nt chn mt t knh ca bnh nh mc, v trn mt cch cn thn bng cch lin tc o ngc bnh. yn cho mt vi pht v sau mang n cho cc du hiu chun 200 ml vi

heptan v mt ln na kt hp mt cch cn thn.6. Tiu chun ha6.1. Cn 200,1 g dung dch Kauri-butanol vo bnh tam gic dung tch 250ml, un cch thy nhit 250C. Chun vi toluen a vo bnh, lc u khi chun , duy tr nhit hn hp trong bnh 25oC. Gim dn lng toluen thm vo khi gn t n im kt thc. im kt thc t cKhi phc tho sc nt ca 10 im in c t trc tip di nc hoc trc tip di bnh v quan st thng qua cht lng c che khut hoc b m nhng khng ti mc bn in tr thnh kh c. Kim tra nhit trong

bnh ngay lp tc sau khi kt thc im t c, nu trn 26 C hoc

di 24oC, lp li cc chun .6.2. Th tch Toluen, a vo, s dng i din cho chun thc t cho gi tr kauri butanol c bit. Gi tr ny nn nm gn vi 105ml nhng khng qu 110 cng khng di 100ml. Nu nhng gii hn ny b vt qu mc, iu chnh nng nng tng s trong chng. Ch nh gi tr cui cng s dng toluen nh A.6.3. Cn 200.1 g ca dung dch Kauri butanol (iu chnh nh m t trong 6.2) vo bnh tam gic 250ml, cho vo ni un cch thy. Chun vi s pha trn heptan-toluen theo cch tng t nh m t trong 6.1. Ch nh th tch, ml a vo, c s dng trong chun ny nh B. 6.3.1.Nu cc thnh phn ca hn hp c bit n khc nhau t 251 phn trm toluen, nhng l trong vng 22 n 28 phn trm dy toluen. Hng s cn bng trong phng trnh pha trn vi yu t khc t 40 bng 0,6 n v i vi mi mt phn trm toluen. V d, 28 % toluen hng s l 41,8 thay v ch 40. 6.3.2. Gi tr kauri butanol va mi chun b c th thay i trong tiu chun t ngy ny sang ngy khc. Do , cc tiu chun ny cn kim tra li vo ngy tip theo cho n yu t toluen v hn hp gi nguyn khng i.6.3.2 Gii php thng - butanola chun b va mi c th i a vo tiu chun ho tng ngy. N l, do , hp dn cho php dung dch tui trc tiu chun ho u tin v, bt lun th no, tiu chun ho nn kim tra li vo ngy lin tip cho n yu t t - luy - en v yu t hn hp gi nguyn khng i. 7. Phng php7.1 . Cn 20 0,1g ca dung dch Kauri- butanol vo bnh tam gic. un cch thy nhit 251oC. Cho vo buret 50ml dung mi c th v chun dung mi a vo bnh vi hng s to thnh xoy . Chun t t khi gn n im kt thc. im kt thc t c khi nhng phc tho sc nt ca cc mu in c t trc tip bn di ni un cch thy hoc trc tip di bnh, v quan st thng qua cht lng, l che khut hoc b m, nhng khng n mc bn in kh c.Kim tra nhit trong bnh ngay lp tc sau khi kt thc im c t c, v nu trn 26 C hoc di 24oC, lp li cc chun . Ch nh th tch dung mi a vo, sn phm t c nh C.8. KT QU V BO CO

8.1 Tnh gi tr kauri-butanol nh sau:

Gi tr kauri butanol = 65(C-B)/(A-B) + 40Trong :

C: Th tch ml mu cn thit chun 20 g thuc th kauri-butanol (xem 7.1)B: Th tch ml hn hp heptan-toluene cn thit chun 20 g kauri-butanol thuc th (xem 6.3),A: Th tch (ml) toluen cn cho vo chun 20 g kauri-butanol tinh khit ( xem 6.2 ).

8.2 Nu buret c duy tr nhit ngoi 25 1oC, iu chnh th tch ca dung mi thng nhit chun nh sau :

iu chnh, ml = C(25 T) x 0,0009

Trong :

C : Th tch ml ca dung mi c s dng trong chun T: Nhit ca dung mi trong buret theo C.9. Chnh xc

9.1 Kt qu s khng khc vi lng gi tr trung bnh bi khong sau :Ch s kauri butanollp li lp li

30 900,01K 0,10,03K + 1

K: gi tr kauri butanol trung bnh