Cacbon disunfua (CS2)Cacbon cng to vi lu hunh mt s hp cht nh nhng hp cht ca cacbon vi oxi. Vd: CS, CS2, C3S2 (ging nh CO, CO2, C2O3)(v S cng nhm vi O, c cu to ho hc tng t O ns2 np4). Quan trng nht trong thc t l CS2. Mt s hnh nh ca cacbon isunfua: - Trong mt phng v trong khng gian:

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Trong khi lin kt:

1) L tnh: - trng thi lng: cacbonisunfua gm nhng phn t n CS2, c cu to ng thng nh CO2: S=C=S ( di lin kt C-S: 1,56 A , nng lng trung bnh ca lin kt: 535 kJ/mol.)0

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iu kin thng: cacbonisunfua tinh khit l cht lng khng mu, nng hn nc (t khi=1,26), khng tan trong nc(CS2 coi nh l cht khng phn cc -> khng tan trong nc), d bay hi (nhit nng chy

42,20C, nhit si -1110C), c mi thm d chu; trong t nhin cacbonsunfua ln tp cht, c mu vng (phn hu chm di nh sng), mi kh chu (ng trong l thu tinh mu nu). - Rt c -> dng lm thuc tr su trong nng nghip. - L dung mi hu c tt (cho brom, iot, lu hunh, photpho, cht bo, sp, cao su, nha,v.v)(theo nguyn tc nhng dung mi khng phn cc s ho tan c cc cht khng phn cc, nhng dung mi phn cc s ho tan c cc cht cht phn cc). 2) Ho tnh: - un nng mnh trong iu kin khng c khng kh: to sn phm cha t lu hunh hn. (C3S2) - Phn ng nhn bit: trong khng kh, hi cacbonisunfua d chy, ngn la c mu lam sng: CS2 + 3O2 -> CO2 + 2SO2 - nhit thng khng phn ng vi nc, 1500C, b thu phn to CO2 v H2S: CS2 + 2H2O -> CO2 + 2H2S - Ging CO2 d chuyn thnh CO32-, CS2 cng d kt hp vi ion S2- to CS32- (ion tiocacbonat), c cu to tng t CO32-(mui ca tiocacbonat u to kt ta, tr mui ca kim loi kim v amoni) K2S + CS2 -> K2CS3 (kali tiocacbonat) 3) ng dng: - Rt c -> dng lm thuc tr su, dit nm trong nng nghip.

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Dng lm dung mi v cht chit(ho tan tt nhiu dung mi hu c). Dng vo cng nghip si nhn to (sn xut si visco)( (A.viscose silk), mt loi si nhn to, c ch to bngcch ngm xenluloz vo dung dch kim 18%, x l tip bng cacbon isunfua (xantogenat xenluloz), sau ho tan hn hp y vo dung dch kim long, c dung dch rt qunh gi l vitco. T vitco, p phun thnh si vo dung dch axit long (t nhn to). Vitco cn c dng ch to giy bng knh (xenlophan).

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Lu ho cao su.

4) iu ch: - Trong cng nghip: CS2 c iu ch bng cch cho hi lu hunh i qua than cc c t nng n nhit 900-10000C trong l in(l in to nhit cao d dng hn): C + 2S -> CS2 , H0 = 122 kJ - Khng c iu ch trong phng th nghim (mc d l dung mi tt nhng li rt c-> khng cn thit iu ch).

Xian (Xianogen) (CN)21) L tnh: - trng thi kh, xian hay xianogen gm nhng phn t kp (CN)2 (thng dc gi ixian). Phn t xian c cu to ng thng. :N C-C N: ( di lin kt C-C 1,37 A v lin kt C-N 1,13 A ) - L kh khng mu, mi xc, d ho lng v ho rn (nhit nng chy -34,40C, nhit si -20,70C), tan trong nc v rt c. - Xian tinh khit kh bn vi nhit, trn 10000C mi phn hu theo phn ng: (CN)2 -> 2[CN]. (trong khi kh Cl2 phn hu 8000C -> nhng gc CN cng ht sc bn vi nhit) 2) Ho tnh: - Khi chu tc dng lu ca tia t ngoi hoc un nng n gn 5000C, xian trng hp thnh khi rn, v nh hnh, mu en, khng tan trong nc, cu to (CN)n c gi paraxian (cu to mch vng cha no)(thm hnh v). Xian rt hot ng. Nhiu phn ng ca xian tng t phn ng ca halogen -> xian cn c gi l halogen gi, v tnh cht, xian nm gia brom v iot. (ta c gc halogen c 7e lp ngoi cng, c khuynh hng nhn 1e t cu hnh bn, trong khi , gc [CN], N t cu hnh bn vi 8e lp ngoi cng, nhng C ch mi 7e lp ngoi cng, do [CN] cng c xu hng nhn 1e nh halogen v c cc phn ng tng t nh halogen)(v hnh trn bng). - Mt s phn ng: (CN)2 + H2 -> 2HCN (CN)2 + Cl2 -> 2CNCl (xianclorua) - Trong khng kh, xian d bc chy cho ngn la mu hng vin xanh c nhit rt cao (xp x 45000C). Trong vng mu hng xy ra phn ng: (CN)2 + O2 -> 2CO + N2 ; vng mu xanh xy ra phn ng chy ca CO: CO + O2 -> CO2. - lu trong nc, xian b thu phn dn theo hai hng: + (CN)2 + H2O HCN + HCNO ; axit ny tip tc thu phn to fomiat amoni v ure (axit xianhidric) (axit xianic) + (CN)2 + 2H2O => H2N-CO-CO-NH2 (oxamiua) ; oxamiua tip tc thu phn to amoni oxalat.0 0

- Trong mi trng kim: (CN)2 + 2NaOH -> NaCN + NaOCN + H2O ( y ta nn phn bit gia bn vi nhit v rt hot ng, bn vi nhit cha chc rt hot ng, bn vi nhit l phn ng t gy lin kt ca phn t do nhit, cn hot ng li cn c vo vic tc dng ca phn t vi cc cht khc, ht e hoc cho e i vi cht khc. Vd tng t nh Cl2, Cl2 kh hot ng, t nhiu phn ng thng dng, th nhng b gy c Cl2 v cng kh khn, ni cch khc, Cl2 bn vi nhit nhng cng rt hot ng.) 3) ng dng: iu ch gc [CN] 4) iu ch: - Trong khi thuc l c nhng vt xian. Xian cng c to thnh gia hai in cc bng than khi cho nit i qua h quang in. - un nng hn hp gm mui Hg(CN)2 v HgCl2 4000C.(s dng mui ca thy ngn m khng s dng cc mui ca cc kim loi khc v, thy ngn l mt cht hon ton khng ging vi bt k kim loi no khc, thy ngn l kim loi duy nht tn ti dng lng; cc kim loi kim, kim th tan trong nc nhng b ion ha to hidroxit, cc kim loi khc khng b ion ha nhng li khng th tan trong nc, ch c thy ngn c th tan trong nc m khng b ion ha) Hg(CN)2 + HgCl2 -> Hg2Cl2 + (CN)2 - Trn dung dch CuSO4 vi dung dch NaCN: 2CuSO4 + 4NaCN -> 2Na2SO4 + 2CuCN + (CN)2 - Xian khng thng c iu ch trong phng th nghim (v cng c hi).