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32 305 2012 LkajyaHpc Xay diitig bai tap trac nghiem Hoa lioc thong qua cac tliih huong co van de trong day lipc IHoa hgc P G S T S C A O c y GIAC Khoa Hda hpc Trudng Dgi hpc Vinh V U MAI LIEN Cao hpe[.]
32 305-2012 LkajyaHpc Xay diitig bai tap trac nghiem Hoa lioc thong qua cac tliih huong co van de day lipc IHoa hgc P G S T S C A O c y GIAC Khoa Hda hpc Trudng Dgi hpc Vinh V U M A I LIEN Cao hpe 18 -PPDH Hda hpc - Trudng Dai hpc Vinh I DAT VAN DE Ngu xay dung duac he thdng bai tap trac nghiem khach quan Iren co sd cae tinh hudng cd van de thi bai tap se dam bao tinli khoa hpc v6 npi dung, logic ve cau tnic, phii hpp vdi doi tupng hpc sinh, gdp phan nang cao hieu qua day hoc ndi chung va day hpc Hda hoc ndi rieng theo hudng hpc sinh nam vung kien thirc ca chicu rpng va chieu sau Mat khac, hoc sinh phat tnen dupe ky nang giai bai tap va phat trien tu- logic Qua dd gay himg Ihii cho mpi dpi luong hpc sinh hpc tap Tinh hudng cd vSn de dupe tao kien thirc hpc sinh da cd khdng phu hpp vdi ddi hdi cua nhiem vu hpc tap hoac vdi thuc nghiem, vSn d^ dua moi nhin ih^y dudng nhir vd li Irai ngirae vdi nguyen li da cdng nhan chung, theo nguyen tac se tao tinh hudng nghich H va be tac * Tinli hudng nghich li : la vln dd mdi nhin dudng nhir vd li trai xoay, ngirpc ddi klidng phii hcrp vdi nguyen li da dugc cdng nhan Diing trudc tin!) hudng hpc sinh tliudng ndi " V6 li klidng the tin dupe" Dieu thudng gap d cac nha klioa hpc ed nhirng phat minh ldi lac gap su kien hien tuong klioa hpe trai vdi li thuyet duong ihdi II NQI DUNG dang thdng tri Chinh nhd nhiing phat mmh Idn dd ma cai Tinh hudng cd van de, van de va bai toan cd van de nghich li da dupe giai quyet de dan den li ihuyet mdi phe - Tmh hudng co van de (THCVD) Id mgi kho khan dirge bd li thuydl cu ldi thdi " Thien tai la ban ciia nghich li" chu the y thirc ro rang hay mo hd, ma mudn khac phuc tin (Puskin) phai lim toi nhung tri ihi'rc mdi, ninnig phuong thi'rc hanh * Tinh hudng be tac - La tinh hudng {li thuyel hoSc thirc ddng nidi nghiem) ma xem xet thi cd mau thuSn va neu dung li - Tinh hudng cd van de kich thich dupe tu hpc smh thuyet da biet de giai thich thi gap be tdc Khi dd phai van hoc sinh s^n cd nliirng tn lliuc ban dau dap trng npi dung dung li Ihuyet hoac quy luat khac de giai thich cu the cua linh hudng, sin cd nhUng phuong tien tri dc de Vi du I: Tai N va P cd eiing dang cau hinh electron "xir sir" vdi ndi dung cu the do, Trudng hop nay, THCVD ngoai cung la ns'np' rftiung N cd cdng hda tri la P trd thanli vrfn de ngoai cdng hda trj cdn cd cdng hda trj 5? Van de la tndt THCVD dugc chii the Hep nhan de giai A Do cau hinh electron ngoai ciing ciia P cd phan Idp d quyel dira tren cac plnrang lien sdn cd cua minh {in thuc, cdn N thi khdng ky ndng, kinh nghiem lim loi) B Do kha nang hoal ddng hda hpc cda P manh han cua N + Mpi van de deu chiia dung THCVD, nhung khdng phai C Do d nliiet thudng N tuong ddi tra ve mat hda hpc bat ky THCVD nao cung deu la van de ca I '"Van de chi xuat hien klii nao da hinh cac dieu D Do nhQng ly khac Hudng ddn Khi dpc de bai loan thi hpc sinh de din den kien de giai quyet chiing" (C Mac) + Chi dat van de nao kha nSng lim each giai quyet linh huong nghich ly, be tac Nhung sau lim hieu dirge epng hoa trj thudng lien quan den cau hinh electron thi van van de dd da chin mudi d mdt hpc sinh, d mdt lop hpc de dupe giai quyet de dang Vdn de lii mot cau hdi hay dugc dai cho chii the md chii the chua biet ldi gidi tir Inr&c vd phdi tim ldi sdng lao Idi gtdi nhung chii the dci cd san mdl s6 phuong "I nC'n ban dau de su dung ihich hop vao viec tim ldi XI - Bid loan co vrm de la mdt van de giai quyet dupe vdi nhQng dieu kien hay thdng sd chp irude Ciic tinh hudng cd van de va bai tap ap dung 2.1 Tinh hudng "nghich ly - be tdc " 33 DgllMHpCsds diem phan va cau tao cua cac nguyen td hay hpp chat —> Chpn dap an A Vi du 2: T^i nila la phi kim manh nhung N2 lai hda hpc Loai tinh hudng giiip cho hoc sinh tich luy tuong ddi tro d nhiet dp thudng? (hay tai nito la phi dupe vdn kien thuc vija ed chifiu rpng vira cd chieu sau kim manh lai tdn tai dupe tir nhien dudi dang tir do?) Vi du 1: Vi dung djch NH3 cd thd hda tan dupe Zn(0H)2? A Nito ed ban kinh nguyen tir nhd B Phan tir N2 khdng phan cue A Zn(0H)2 la mot baza lan C Nito cd dd am dien Idn nhat nhdm VA B Zn{0H)2 la hidroxit luang tinh C NH3 la mdt hop chSt ed cue va la mdt bazo y6u D Lien ket trpng phan tir N2 la hen kSt ba ril bdn Hudng ddn: Nilo la phi kim manh, nhung dan chat niia D Zn"" cd kha nang tao phuc chit tan vdi NH3 hoat ddng hda hpe kem d nhiet dp thudng, ton lai dupe Hu&ng ddn: Khi cho Zn{0H)2 vao dung djch dung djch irong tu nhidn (khi quyen) vi phan tu N2 ed lien ket ba NH3 thi ed phan ung sau: (N=N) rat ben, khdng the phan hity nguyen tir Zn(OH)j+4NH3 ^[Cu{NH3)4](OH)j ^ D a p a n D nhiel dp thap hpae khdng ed xiic tac —> Chpn dap an D Vi du 2: Tai H3PO4 khdng cd tinh oxi hda nhu HNO3? 2.2 Tinh huong "lira chgn " A Do nguyen Hi P irong phan tir H3PO4 cd lai hda sp^ La linh hudng dai tnrde hpc sinh lira chpn ral khd khan, B Do nguyen tir P phan tu H3PO4 cd sd 0x1 hda la +5 vua eo le, vira oai oam ea ve lam li lan ky thuat giu'a hai hay nhieu phuong an giai quyel ma hoc sinh chi duoc phep C Do nguyen td P phan tir H3PO4 cd lai hda sp^ la dang lai hda b§ii va cd sd 0x1 hda la +5 chpn mdt ma thdi Vi du 1: Hda tan 4,76g hdn hpp kim loai gdm Zn va Al cd D Do nhCrng ly kliac ti le moi vao 400 ml dung djch HNO3 vua du thu duoc dung djch X chira m gam mudi va khdng cd thoat Gia trj m la ' A 25,8 B 26,4 C 27,8 D 24,6 Huang ddn • ui„ = 0,04 va UAI = 0,08 -^ ne(nhudng) = 2.nzn + 3,nAi = 0,32 Khdng cd thoat —> cd mudi NH4NO3 va ne{nhan lao khi) = Suy ra: m = 4,76 + 62.0,32 + 80.0.04 - 27,8 - ^ Dap an C Vi du 2: Phuong phap dieu chfi elanol nao sau day chi diing phdng ihi nghiem? A Len men glucozo B TTiiiy phan dKn xuat elyl lialogenua Irong mdi Inrdng kidm Huang ddn • Nguyen tir N U-ong phan lur HNO3 cd cdng hda Iri IV, cd sd 0x1 hda -1-5 va lai hda sp^ Cdn phan lu H3PO4 nguyen tii P cd sd 0x1 hda la +5 va lai hda sp' la dang lai hda b^n nen khdng cd tinh oxi hda nhu H N O , H ,0 Cdu lao ciia axil mine HNOi " ° \ Cdu lao cua axil pholphoric H_tP04 III KET LU.\N Xay dung mdl he thdng bin lap tren co sd khai thac cac tinh hudng cd van de la vi^c lam can thiet ciia giao vien d^y hpc Mpi tinh hudng cd mpt ngudn gdc xuat phat D Cho hon hpp etylen va hai nudc qua thap chii-a HjP04 Hudng ddn Tit ca trudng hop da cho deu cd ihe dieu khac cd bieu hien ve tam ti khac Do dd, cd nhQng each giai quyet khac ma giao vien can phai chd dupe etanol Tuy nhien Irong phdng Ihi nghiem, ngudi nam v5ng de dan dat hpc sinh giai quyet van de mdt each la Ihuc hien nhanh biing phuang phap thiiy phan din xuat Iron ven ctyl lialogenua Irong mdi trudng kiem -^ Dap an B C, Cho etilen t^c dyng vdi HiSO^ loang ndng 2.3 Tinh hudng "igisao" Lk tinh huong cd van de xuai hi^n yeu cau phai tim kidm nguyen nhan ciia mdt kel qua ngudn gdc ciia mdt hi^n tupng, tim Idi giai dap eho cau hdi " tai ?" Day la tinh hudng phd bien thudng xuyen va rat hieu nghigm irong qud trinh nh5n thirc chung va nhan thirc hda lioc ndi rieng Trong day hda hpc, chiing ta thudng xuyen g?p phai tinh hudng "lai sao" Dd la nh&ng cin giai ihich hi^n lupng, nhi>ng tinh ch^l hda hpc d^a vao dac T i l LIKU THAM KHAO: Cao Cu Giac Bdi tap ly Ihuyet vd (hue nghiem Hda hoc, lap I - Hda hoc Vd ca Nxb Giao due, H.2003 Cao Cy- Giac KT ihiidl phan lich vd giai nhanh bdi lap trac nghiem hda hoc Nxb Dai hoc Qudc gia TP Hd Chi Minh, 2009 Nguyen Ngoc Quang Li hidn dgy hoc Hda hoc Tap Nxb Giao due, H.1994 ... ciia giao vien d^y hpc Mpi tinh hudng cd mpt ngudn gdc xuat phat D Cho hon hpp etylen va hai nudc qua thap chii-a HjP04 Hudng ddn Tit ca trudng hop da cho deu cd ihe dieu khac cd bieu hien ve tam... hudng "igisao" Lk tinh huong cd van de xuai hi^n yeu cau phai tim kidm nguyen nhan ciia mdt kel qua ngudn gdc ciia mdt hi^n tupng, tim Idi giai dap eho cau hdi " tai ?" Day la tinh hudng phd bien... thudng xuyen va rat hieu nghigm irong qud trinh nh5n thirc chung va nhan thirc hda lioc ndi rieng Trong day hda hpc, chiing ta thudng xuyen g?p phai tinh hudng "lai sao" Dd la nh&ng cin giai ihich