| T O P I C R E V I E W |
| xine-danlinh |
Posted - 04/04/2003 : 14:43:48
ba con oi ! tui hoi ti xiu . muoi Fe2+ phan ung voi axit HNO3 thi ra muoi sat2 hay sat3 .minh nghi la muoi sat3 nhung thang ban minh cai la muoi sat2. help me!nhanh nhe!
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| 15 L A T E S T R E P L I E S (Newest First) |
| Hihihahihi |
Posted - 04/16/2003 : 20:38:29
Thay cac ban tranh luan ve hien tuong enol hoa hay qua nen toi tham gia chut xiu cho vui!
Can bang xeto-enol phu thuoc vao nhieu yeu to,nhu nhiet do,nong do,dung moi,cau tao,....
Trong truong hop cac hop chay cacbonyl don gian (hop chat co mot nhom cacbonyl lien ket voi cac nhom don gian nhu hidro,alkyl.. can bang xeto-enol se lech han ve phia dang cacbonyl:
CH2=C(OH)-CH3 ----> CH3COCH3
Neu trong phan tu co nhom voi hieu ung -C de co the lien hop voi he enol do do' lam tang do ben cua dang enol thi can bang se lech ve dang enol:
CH3-CO-CH2-CO-CH3 ---> CH3-C(OH)=CH-CO-CH3
Trong truong hop axetylaxeton,axetoaxetat etyl va cac he phan tu tuong tu,do ben vung cua dang enol con duoc quyet dinh boi mot so yeu to quan trong khac nua la su tao thanh lien ket hidro noi phan tu.
Duoi dday la ham luong dang enol doi voi mot so hop chat cacbonyl khac nhau:
.......................Enol, %
CH3-CO-CH3............2,5.10^(-4)
CH3-CHO .............khong dang ke
CH3COOC2H5 ...........khong dang ke
CH3COCH2COOC2H5.......7,5
CH3COCH(C6H5)COOC2H5....30
CH3COCH2COCH3...........80
Ham luong dang enol cua mot hop chat cacbonyl nhat dinh o trang thai nguyen chat khac o trang thai dung dich vi co anh huong cua dung moi.Thi du: axetoaxetat etyl trong nuoc co 0,4% dang enol,trong hexan co 46,4%;axetylaxeton trong nuoc co 15% enol con trong hexan co 92%.So di cac ham luong enol giam manh khi di tu dd hexan den dd nuoc vi nuoc tao lien ket hidro voi dang cacbonyl,do do lam cho cang bang xeto-enol lech ve phia xeto.
(Cac ban co them tham khao them trong "Co so li thuyet hoa hoc,tap 2,phan co che cua thay Tran Quoc Son!)
Moi cac ban ghe tham CLB Hoa Hoc:
http://ttvnol.com/forum/f_347
http://hoahoc.ttvnonline.net
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| Hihihahihi |
Posted - 04/16/2003 : 20:21:09
tr�ch:
Tui thay cai ten hihihahihi nay hoi bi quai do , ong khong the noi chuyen tu te mot teo sao ma cu phan bac nguoi khac ghe the.A, ma ong hoi bi chanh day , ong dam noi Fe2+ khi tac dung voi bat ki chat gi cung cho ra Fe3+ ha? sai bet! cho ong mot vd don gian ne:
FeCl2 + 2AgNO3 = Fe(NO3)3 + 2AgCl(Ket tua)
Phan ung viet sai kia`! Y toi noi la trong phan ung oxi hoa khu,mot chat (vi du Fe2+ trong truong hop nay) khong the giu nguyen so oxi hoa cua no duoc!
Lam gi ma co ve "cay cu" toi the! Hic hic!
Moi cac ban ghe tham CLB Hoa Hoc:
http://ttvnol.com/forum/f_347
http://hoahoc.ttvnonline.net
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| xine-danlinh |
Posted - 04/10/2003 : 19:40:42
salem a! y kien cua Nguyen hoang giang la dung day . (bo xung them y kien cua Trang1985 nua la du )
Jame ! cau noi dung do ben cua no phu thuoc vao hai yeu to
-moi truong
-so nhom -OH co trong chat
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| jamepotter5 |
Posted - 04/10/2003 : 18:59:25
Chao Xine-danlinh , to khong biet cau va Salem da ban luan xong ve van de cau hoi chua vi Salem noi cau email cho cau i . Nhung to van co y kien mot ti nghen!
Theo to nghi thi nhom -OH gan voa noi doi la khong ben , Nhung muc do khong ben den muc nao thi con phu thuoc vao nhieu yeu to khac.
Vd CH3-(OH)C=CH-C=0CH3(1) , co dang ben la CH3-CO-CH2-CO-CH3(2)
Trong dd (1) it hon (2) nhung tuong doi on dinh, do hieu ung lien hop
pi-pi, va lien ket Hidro giua oxi(gan o noi doi) voi Hidro cua nhom
-OH.
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| salem85 |
Posted - 04/10/2003 : 14:18:15
Fe tac dung voi HNO3 o bat ky dk nao cung => Fe3+ tru truong hop HNO3 dac nguoi ko phan ung voi Fe
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| trang1985 |
Posted - 04/10/2003 : 00:57:14
tui cung dong y voi y kien cua ban.O trong bo de cung co bai viet phuong trinh phan ung nhu vay.Nhung hinh nhu phan ung nay rat kho xay ra trong thuc te.
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| Nguyen Hoang Giang |
Posted - 04/09/2003 : 23:29:37
Re:ba con oi ! tui hoi ti xiu . muoi Fe2+ phan ung voi axit HNO3 thi ra muoi sat2 hay sat3 .minh nghi la muoi sat3 nhung thang ban minh cai la muoi sat2. help me!nhanh nhe!
Khi muoi Fe+2 phan ung voi HNO3 (dieu kien: loang, lanh) thi ra Fe+2. Toi nghi la the. Day la truong hop rieng cua Fe. Con lai thi no se dua Fe ve so oxi hoa cao nhat
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| xine-danlinh |
Posted - 04/09/2003 : 16:12:16
Jamepotter! tui ra^'t thi'ch ddo.c harry potter cha'c cha'n ba.n cu~ng va^.y .
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| salem85 |
Posted - 04/09/2003 : 09:21:52
Xin loi nha tui go = unicode nen khong biet la ban khong doc duoc.
tui cu tuong ban hoi ve OH gan truc tiep vao 4 lk doi.
Tui khong hieu ro lam cau hoi cua ban. Theo tui nho thi OH gan truc tiep vao C lk 2 thi se xay ra hien tuong chuyen vi. Neu la CH2=CHOH se cho ra CH3CHO con cac dong phan sau se cho ra ete. Neu co gi ban co the gui email cho tui duoc khong? chu khong dau kho hieu qua
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| xine-danlinh |
Posted - 04/09/2003 : 03:39:05
kho doc qua salem oi . nhung y minh khong phai la -OHgan truoc tiep vao benzen dau . ban doc quyen sach " mot so phan ung cua hop chat huu co " cua TRAN QUOC SON chua ? o trang 161 phan chu nho co : viet * cung vi su phan cuc manh cua nhom cacbonyl , andehit va xeton co the Enol hoa theo mot can bang
2-propanon <-> 1-metyl propenol-1
qua trinh enol hoa co the duoc xuc tac bang axit hoac bazo.
.... cac hop chat co mot nhom cacbonyl enol hoa rat kem . cac hop chat co nhieu nhom cacbonyl co the enol hoa de dang. thi du trong dung moi dioxan, axetylaxeton CH3CO-CH3-COCH3 ton tai chu yeu o dang enol (toi 80 0/0 )
khi minh hoi thay hoa ve van de nay thay da phu nhan vi the minh hoi de tim cau tra loi cua cac ban .
con cau hoi thu 2 minh nghi phai giai thich dua tren cac eletron hoa tri o trang thai co ban va trang thai bi kich thich . cac ban thu viet su phan bo theo obitan o cac trang thai khac nhau xem co giai thich duoc khong .
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| salem85 |
Posted - 04/08/2003 : 17:11:49
� bạn muốn n�i l� OH gắn trực tiếpv�o v�ng benzen hả
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| jamepotter5 |
Posted - 04/08/2003 : 17:05:59
Tui thay cai ten hihihahihi nay hoi bi quai do , ong khong the noi chuyen tu te mot teo sao ma cu phan bac nguoi khac ghe the.A, ma ong hoi bi chanh day , ong dam noi Fe2+ khi tac dung voi bat ki chat gi cung cho ra Fe3+ ha? sai bet! cho ong mot vd don gian ne:
FeCl2 + 2AgNO3 = Fe(NO3)3 + 2AgCl(Ket tua)
Tu Fe2+ van cho ra Fe2+ do, ong con sai mot loi nua do la Fe2+ cho ra Fe2+ khong phai la giu nguyen chat ma la giu nguyen so oh ,vi the neu khong phai phan ung oxi hoa khu thi khong co su thay doi so oxi hoa dau. Coi lai Hoa Hoc lop 10 di. Bye!
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| datacnhang1 |
Posted - 04/08/2003 : 10:54:17
BA OI BA BIET ROI MA CON HOI KHO TUI NAY VAY
BA VE XEM LAI KIEN THUC VE RUOU
CON VE Mn THI VE XEM LAI KIEN THUC LOP 11 PHAN CAU TAO NGUYEN TU
THE BA NHE!
BYE
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| xine-danlinh |
Posted - 04/07/2003 : 19:52:05
    ba con khong giai duoc a ?
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| xine-danlinh |
Posted - 04/06/2003 : 21:14:06
co van de moi hoi moi nguoi day . ba con nghi sao ve su ben cua ruou co nhom OH dinh truc tiep vao cac bon lien ket doi . chac chan rang khong phai moi truong hop no deu khong ben dau .con nua , tai sao Mn lai co hoa tri 2,4,6,7 ma Fe lai chi co hoa tri 2,3thoi.
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