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CAÙC THUYEÁT ACID - BASE HOÙA VOÂ CÔ

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  • CAC THUYET ACID - BASEHOA VO C

  • Cac loai phan ng khong thay oi so oxy hoaPhan chia theo quan iem acid - base 1. Phan ng acid base La phan ng hnh thanh lien ket cong hoa tr t 1 cap electron cua mot chat va 1 orbital trong cua mot chat khac.

  • V du: H+(k) + Cl- (k) = H Cl (k)NH3(k) + BF3(k) = H3N BF3 (r) (NH3.BF3)NH4+ + OH- = NH3 + HO H (NH3.H2O)NaOH (r) + CO2 (k) = NaHO-CO2 (r) (NaHCO3)H+(aq) + OH- (aq) = H OH (l)Cu2+ (aq) + NH3(aq) = [Cu NH3]+(aq)CaO(r) + SiO2 (k) = Ca2+[-O SiO2-](r) (CaSiO3)Chat cho cap electron la base, chat nhan cap electron la acid.

  • 2. Phan ng phan huy

    La phan ng pha huy chat phc tap tao thanh chat n gian hn.

    V du: CaCO3(r) = CaO (r) + CO2(r)

  • 3. Phan ng ket tua t cac ion

    La phan ng lien ket cua cac ion tao thanh chat ran co lien ket ion. V du: Ag+(aq) + Cl- (aq) AgCl(r) + aqBa2+(aq) + SO42-(aq) BaSO4(r) + aqCac phan ng loai nay eu co tnh thuan nghch.

  • 4. Phan ng goc La phan ng tao thanh mot lien ket n cong hoa tr t 2 goc t do.V du: H + H = H H5 Phan ng polimer hoa La phan ng tao thanh ai phan t t rat nhieu phan t cung loai. V du: nSO3 (k) (-OSO2-OSO2-OSO2-)n/3 (r)

  • Cac thuyet acid base va lnh vc ap dung cua no I . THUYT ACID BASE ARRHENIUS (1887)nh ngha: acid la chat phan li trong nc cho ion H+, base la chat phan li trong nc cho ion OH-.V du: HCl (k) H2O H+(aq) + Cl-(aq)

    NaOH (r) H2O Na+(aq) + OH-(aq)

    Thuyet nay ch ung trong dung dch nc

  • II. THUYET ACID BASE BRONSTED-LOWRY

    Da tren tnh chat proton, H+: khong co lp vo electron, ch la hat nhan nen kch thc rat nho, H+ co the xam nhap sau vao lp vo cua cac ion, phan t khac e thc hien phan ng trao oi ion. 1. NH NGHA:Acid la tieu phan cho proton (H+), con base la tieu phan nhan proton trong phan ng.Thomas Martin Lowry Johannes Nicolaus Brnsted

  • V du:HCl H+ + Cl-H2SO4 H+ + HSO4-V acid la chat nhng H+ va base nhan H+, nen trong 2 v du tren ta co cac cap acid, base:HCl/Cl- va H2SO4/HSO4-Nhng cap acid/base nh vay goi la cap acid/base lien hp.Cac acid, base Bronsted co the la phan t trung hoa, cation hoac anion.

  • D on axit baz BronstedAxit l cc cht phi c cha H+. Cation: NH4+Cc cation kim loi b hydrat ha trong ncV d:Al3+ + 6H2O [Al(H2O)6]3+[Al(H2O)6]3+ [Al(H2O)5OH]2+ + H+Anion: HSO4-, H2PO4-Phn t trung ha in: HCl, H2SO4, H2O Baz cht c d mt in tch m:C in tch m (anion): Cl-, SO42-C phn cc m (phn t phn cc - bt i xng trong khng gian): NH3, HCl

  • ACIDBASETRUNG HOAHCl H+ + Cl-

    H2O H+ + OH-NH3 + H+ NH4+

    H2O + H+ H3O+ANIONHSO4- H+ + SO42-

    HCO3- H+ + CO32-CH3COO- +H+CH3COOH

    Cl- + H+ HClCATIONNH4+ H+ + NH3

    H3O+ H+ + H2O

  • Lng tnh: va c KN cho, va c KN nhn H+ Cc hp cht c cha H+ thng l cc cht lng tnhV d:H2O + H2O H3O+ + OH-HF + HF H2F+ + F- Kcb = KS H2SO4 + H2SO4 H3SO4+ + HSO4-Khi phn ng vi axit mnh hn: lng tnh = bazKhi phn ng vi baz mnh hn: lng tnh = axitV d: H2PO4- + HCl H3PO4 + Cl-H2PO4- + HCO3- HPO42- + H2CO3 pKa2 7.21 10.33Trung tnh: va khng c kh nng nhng, va khng c kh nng nhn H+Cation kim loi khan: Na+, Ca2+Phn t khng phn cc: CO2, B2Cl6

  • Do H+ khong ton tai c dang t do, nen cac acid ch cho proton khi co base nhan va ngc lai.

    Phan ng trao oi proton xay ra tong quat gia hai cap acid-base lien hp nh sau:

    A1 + B2 A2 + B1

  • Trong dung dch, cac phan t va ion do dung moi ien ly ra cung ong vai tro cua cap acid-base lien hp.

    H3O+/H2O; H2O/OH-

    Cac hp chat co cha H+ luon la chat lng tnh, phu thuoc vao chat phan ng vi no co kha nang cho, nhan H+ manh hay yeu hn no.

  • 2. CNG ACID-BASE BRONSTED TRNG THI KH:

    Ta co the anh gia kha nang nhan H+ cua mot base thong qua hieu ng nhiet cua qua trnh trong pha kh.B (k) + H+(k) = BH+(k), H = -Q ay Q la nang lng giai phong ra cua qua trnh.Q cang ln th H cang am, qua trnh ket hp cang manh. Base B cang manh th acid lien hp BH+ cang yeu.

  • Bang cac gia tr Q (kJ/mol) (trang 7 tai lieu T2 NTTNga)

    IonPhan tIonPhan tH-1674H2423F-1554F2399PH2-1541PH3789Cl-1398HCl564AsH2-1501AsH37Br-1354HBr589CH3-1743CH4552I-1315HI628N3-3084O2-2318NH2-2565OH-1635H 2O679NH2-1689NH385S2-2300NCl3795SH-1478H2S712NF3556Se2-2200SeH-1420H2 Se717

  • e xac nh cng o cua cac acid, ngi ta da tren cac gia tr Q cua cac base lien hp cua chung.V du:F-(k) + HCl(k) = HF(k) + Cl-(k) Q (kJ/mol) 1554 1398Ta thay F- la base manh hn Cl- (Q ln hn), nen F- lay c H+ cua HCl.

    Bang gia tr Q cua cac base lien hp cua acid trang 9 T2 NTTNga (Q cang ln acid cang yeu).

  • 3. CNG O ACID-BASE BRONSTED TRONG DUNG MOI PROTON HOA

    DUNG MOI PROTON HOA:La cac dung moi co the b t ion hoa mot phan khi trang thai long tao H+.Do H+ khong co lp vo electron, nen ch la mot ien tch iem vi mat o ien tch dng rat cao. Do o, khi trang thai long (khoang cach cac phan t rat gan nhau), H+ khong ton tai t do ma luon b solvat hoa bi cac tieu phan dung moi quanh no.

  • V du: H2O(l), NH3(l), H2SO4(l), HCl(l)Vi nc: H2O + H2O = H3O+ + OH-

    Tong quat, vi dung moi proton hoa HSol, ta co:HSol + HSol H2Sol+ + Sol- , KSHang so can bang cua qua trnh nay goi la Hang so t proton hoa KS:

    KS = [H2Sol+][Sol-], do [HSol] xem la hang so.Vi nc KS = [H3O+][OH- ] = 10-14 220C.

  • Cac dung moi proton hoa la nhng chat lng tnh theo quan iem acid-base Bronsted.

    Trong cac dung moi proton hoa co mat 2 cap acid/base lien hp:Sol- + H+ HSol (HSOl/Sol-)HSol + H+ H2Sol+ (H2Sol+/HSOl)

  • Cng o acid-base cung c xet da tren ai lc proton cua chung, tc la Hs = -Qs cua qua trnh (Qs Q pha kh).

    V du trong pha kh: H+(k) + OH-(k) = H2O(k), H= -Q = -1635kJ/molTrong pha long:H+(aq) + OH-(aq) = H2O(l), H= -Qs = -1188kJ/molH+(aq) + H2O(l) = H3O+(aq), H= -Qs = -1130kJ/molKhi hoa tan 1 chat, Qs phu thuoc vao dung moi, Qs ln th tnh base manh.

  • Vi acid HA trong H2O:HA + H2O H3O+ + A-Neu HA manh hn H3O+ th can bang theo chieu thuan Trong nc khong co acid manh hn H3O+.Vi base B trong H2O:B + H2O BH + OH-Neu B la base manh hn H2O th can bang theo chieu thuan Trong nc khong co base manh hn OH-.

    HIEU NG CAN BANG:Trong dung dch nc khong the co mot acid manh hn H3O+ va mot base manh hn OH- (m rong cho ca cac dung moi HSol khac).o manh cua acid/base phu thuoc vao o manh dung moi, anh gia bang hang so can bang trong qua trnh trao oi proton cua chat o vi dung moi.

  • CNG O CUA ACID BRONSTEDCng o cua acid proton HA hoa tan trong dung moi proton hoa c anh gia bi hang so can bang:HA + HSol H2Sol+ + A-

    Trong H2O, tng t ta co:

    Ka: Hang so acid

  • Ka cang ln th tnh acid cang manh.Ka phu thuoc ban chat acid, dung moi va nhiet o. o manh cua acid con phu thuoc vao dung moi, dung moi co tnh base cang manh th HA the hien tnh acid cang manh.

    VD: HClO4 la acid rat manh trong dung dch nc (Ka=1010), nhng trong CH3COOH lai la acid yeu (Ka=10-6)

  • CNG O CUA BASE BRONSTEDTng t nh acid:B + HSol HB+ + Sol-

    Kb cang ln th base cang manh.

  • LIEN HE GIA Ka VA KbTrong mot cap acid/base lien hp, ta co lien he:HA + HSol H2Sol+ + A-A- + HSol HA + Sol-

    Viva

    Ka Kb = [HSol+][Sol-] = Ks

    Trong dung dch nc ta co:KaKb = Kn = 10-14 220C.

  • Mot so acid/base lien hp

    AcidKapKaBase lien hpKbpKb HI3 x 109-9.5I-3 x 10-2423.5HCl 1 x 106-6Cl- 1 x 10-2020 H2SO4 1 x 103 -3HSO4- 1 x 10-1717H3O+ 55 -1.7 H2O 1.8 x 10-16 15.7HNO3 28-1.4NO3-3.6 x 10-1615.4 H3PO4 7.1 x 10-32.1H2PO4- 1.4 x 10-12 11.9 CH3CO2H 1.8 x 10-54.7CH3CO2- 5.6 x 10-109.3H2S 1.0 x 10-7 7.0 HS- 1 x 10-77.0H2O 1.8 x 10-1615.7 OH- 55-1.7CH3OH 1 x 10-1818CH3O- 1 x 104-4 HCCH 1 x 10-2525 HCC-1 x 1011-11 NH3 1 x 10-33 33NH2-1 x 1019 -19 H2 1 x 10-3535 H-1 x 1021 -21 CH2=CH2 1 x 10-4444CH2=CH-1 x 1030 -30 CH4 1 x 10-4949CH3-1 x 1035-35

  • NHAN XET VE TNH ACID CUA HnXTrong mot chu ky, i t trai qua phai, ai lc e tang dan, o ben lien ket tuy tang nhng khong nhieu do ban knh nguyen t giam t. V vay tnh acid tang dan.VD: Tnh acid HF > H2O

    Trong mot phan nhom, khi i t tren xuong, o ben lien ket giam nhanh hn ai lc e giam, nen tnh axit tang. VD: Tnh acid HF < HCl < HBr

  • Cac acid cha Oxy, H hoac nhom OH th phu thuoc vao o am ien nguyen t trung tam lam o phan cc lien ket O-H hay X-H thay oi dan en thay oi cng o acid.

    Cac hydroxyt lng tnh: Nguyen t trung tam la kim loai kem hoat ong hay phi kim co o am ien nho, hai lien ket MOH va OH co o phan cc gan nhau. V vay tnh acid/base phu thuoc moi trng.OH- + M MOH MO- + H+

  • Quy luat bien oi cng o cua acid-oxy (Quy tac Pauling)

    Acid-oxy c chia thanh cau trucHaXOn(OH)m (X: nguyen t trung tam).a: So nguyen t H lien ket trc tiep vi X.n: So nguyen t O lien ket vi X nhng khong lien ket vi H.m: So nhom OH lien ket vi X. So n quyet nh cng o acid.

  • N = 0 acid rat yeu. VD: Te(OH)6, Cl(OH)N = 1 acid yeu.VD: NO(OH), PO(OH)3, SO(OH)2N = 2 acid manh.VD: SO2(OH)2, ClO2(OH), NO2(OH)N = 3 acid rat manh.VD: ClO3(OH)

  • Nhan xet: OH, H lien ket vi X khong anh hng nhieu en cng o acid (do O lien ket trc tiep X hut e manh X cang dng, nen lien ket O-H cang b phan cc de H+).Cac acid co cung cau truc (a,m,n), neu X tang o am ien se lam tnh acid tang (nhng khong ro ret).

    Quy tac thc nghiem Pauling tnh Ka:Cho acid HaXOn(OH)m. pKa = 7 5nQuy tac nay tnh pKa1 gan ung khi biet cau truc.VD: HClO (n = 0) co pKa = 7; H2SO4 (n = 2) co pKa = -3.

    Vi cac bac tiep theo: pKa(n+1) = pKa(n) + 5

  • Quy tac Kartletch (tham khao):Vi q va r : ien tch va ban knh ion trung tam (tnh bang coulomb va ). < 2.2 : Base. 2.2 3.2 : Acid.Quy tac nay giai thch c s thay oi tnh acid cua acid n ma khong can en cau truc (khong ung vi acid a chc).VD: KOH base manh.

    H2SO4 acid manh.

  • 4. PHAN NG THUY PHAN THEO BRONSTED-LOWRY1. Thuy phan cac muoi trong dung dch ncThc chat la cac phan ng trao oi proton gia cac ion do muoi phan ly va cac phan t nc.

    a. THUY PHAN CATIONQua trnh thuy phan cation xay ra khi cation la axit manh hn nc, no nhng H+ cho nc (M+ dang dung dch)[M(H2O)m]+n + H2O [M(H2O)m-1OH]+(n-1)+H3O+

  • HSCB chnh la Ka cua acid [M(H2O)m]+n hay con goi la hang so thuy phan Ktp.

    Mc o thuy phan cation se tang dan theo o manh acid, tc la cation co pKtp nho hn th tnh acid manh hn de thuy phan hn.

    S thuy phan cua Cation s cng mnh khi tc dng phn cc nc ca cation (phu thuoc vao ien tch (so oxy hoa), ban knh va cau hnh electron ca ion) cng mnh VD: Mn2+ (pKtp = 10.7) va Hg2+ (pKtp = 3.7) th Hg2+ co tnh acid manh hn va thuy phan manh hn.

  • b. S THUY PHAN CUA ANION

    Anion cua muoi la base, neu no manh hn H2O th no se lay H+ cua H2O nng OH- trong dung dch tang.A- + H2O AH + OH-

    o manh cua base da vao acid lien hp cua no.Cac anion la base qua manh (O2-, N3-) b thuy phan hoan toan khong ton tai ion nay trong dung dch.O2- + H2O 2OH-N3- + 3H2O NH3 + 3OH-

  • Cac base qua yeu (yeu hn nc) khong b thuy phan.VD: SO42- (Kb = 10-11) hau nh khong b thuy phan.

    Muoi gom cation va anion: Neu ch co cation b thuy phan moi trng acid, neu ch co anion b thuy phan moi trng base. Neu ca hai b thuy phan th pH dung dch do ion b thuy phan manh hn quyet nh.

  • 2. Thuy phan cac hp chat cong hoa tr

    Cac hp chat cong hoa tr khong b thuy phan trong nc ma trc tiep chu s phan huy bt thun nghch cua nc. Phan ng thuy phan tao thanh 2 acid: Acid-oxy va hydraxit (hydro-acid).

    VD: BCl3 + 3H2O H3BO3 + 3HCl SiCl4 + 4H2O H4SiO4 + 4HCl SO2Cl2 + 2H2O H2SO4 + 2HCl

  • III. THUYET ACID BASE LEWIS1. NH NGHA:Base la chat cho cap electron va acid la chat nhan cap electron e tao thanh lien ket hoa hoc.Khai niem nay lien quan en lien ket cong hoa tr cho nhan.Acid Lewis:La nhng tieu phan co d mat o ien tch dng, trong phan t (ion) co cac orbital trong co the tiep nhan cap e chuyen en t base. V du: a so cac cation la acid Lewis (Ag+, Co3+, Cr3+), hay cac halogen, hydrua cua B, AlGilbert Newton Lewis

  • Base Lewis:La nhng tieu phan co kha nang cho i cap e.V du: Cac anion (Cl-, Br-, OH-), cac phan t trung hoa hoac ion trong thanh phan co cac nguyen t con cap e cha lien ket nh N, O (NH3, ru, cetone).Acid BaseAg+ + NH3 [Ag(NH3)2]+BF3 + F- [BF4]-HCl + NH3 NH4Cl

  • 2. Cng o acid-base LewisRat kho so sanh cng o acid-base Lewis v con phu thuoc vao lien ket CHT gia cac chat.Co the xac nh da tren: S phan ly trong pha kh, so sanh o ben cua san pham tao thanh gia cac acid va base V du tnh base cua day sau giam :

    Hp chatH phan ng vi B(methyl)3(kJ/mol)Tnh chat san pham p/ vi HCl(Methyl)3N-74Thang hoa 2500C(Methyl)3P-67Thang hoa 1250C(Methyl)3AsPhan ng di -800CKhong ben (to thng)(Methyl)3PbKhong phan ngKhong ben tren -800C

  • Cac hieu ng cam ng, cong hng, khong gianco tac dung rut e lam tnh acid tang va tnh base giam.

    Khi ch xet lien ket gia acid (nguyen t trung tam nhan cap e) va base (phoi t co cap e) th tnh acid tang t le vi mat o ien tch dng tren nguyen t trung tam va tnh base tang t le vi mat o ien tch am tren phoi t.VD: Tnh base tang dan trong day:I-

  • Hieu ng cam ng V du: Tnh base giam dan trong day Li3N, NH3 , NF3 do tac dung rut electron tang dan t Li en F

  • Hieu ng lap the (khong gian)V du: Tnh base giam theo day 3-metylpyridin (CH3C5H5N)(b), pyridin (C5H5N)(a), 2-metylpyridin (c) trong phan ng vi B(CH3)3 (trimetylbor) mac du nhom metyl co hieu ng cam ng ay electron, nguyen nhan la do s can tr khong gian cua nhom metyl ti N. Ho298 cua cac phan ng tren lan lt

    (a) -71kJ (b) -74kJ c) -42kJNgoai ra con phu thuoc vao kha nang tao lien ket cua tieu phan acid va base (Th du se neu trong phan phc chat)

  • Hieu ng cong hng V du:

    Tnh acid tang dan trong day BF3, BCl3, BBr3 do co hieu ng chuyen electron t halogenide sang Bor tao lien ket theo c che cho nhan . Hieu ng nay yeu dan t F en Br, dan en mat o ien tch dng tren B tang dan t BF3 en BBr3.

  • Ket luan:Ch co the tnh o manh acid base Lewis cho tng nhom chat. Khong co thc o chung nh trng hp acid base Bronsted Lawry.

    o manh cua acid base Lewis tnh theo nang lng lien ket (J/mol) tao gia acid va base Lewis hay theo hang so ben cua phc (trong dung dch)

  • 3. Phan ng tao phc

    Do cation kim loai Mn+ con co AO trong (do mat e hoa tr) nen co kha nang nhan cap e cua cac phan t co tnh base Lewis tao lien ket cong hoa tr.Mn+ + L Mn+LIon trung tam Phoi t Phc chat

    Hang so ac trng cho o ben cua phc chat ML+n.

    K cang ln th phc tao thanh cang ben.

  • Neu Mn+ co the phan ng nhieu bac e tao phc vi L MLmn+ th ng vi tng bac phan ng ta se co he so ben tng bac:Mn+ + mL MLmn+

    Hang so ben tong m=K1K2KnNeu Mn+ la acid cang manh va L la base cang manh th phc cang ben hay mva K cang ln.

  • e so sanh cng o base, co the so sanh hang so ben cua phc chat gia base o va 1 kim loai nao o c chon lam chuan.VD: [FeF-4] = 1015, con [FeCl-4] = 0.85FeF-4 ben hn FeCl-4 nhieu F- la base manh hn Cl- nhieu.

    Ngc lai cung co the chon 1 base lam chuan e so sanh cng o cac acid Mn+. Nhng ket qua khong chnh xac khi chon cac base khac nhau lam chuan.

  • Giai thch:Do Mn+ co kch thc nho, nen yeu to khong gian anh hng en lien ket, hay do Mn+ tao lien ket vi cac phan t khac nhau nen anh hng en o ben phc chat.VD: So sanh Ag+ va Fe3+ vi F- va Cl-, ta co:Fe3+ + F- FeF2+ , lgK1 = 6.06Ag+ + F- AgF , lgK1 = 0.36Fe3+ + Cl- FeCl2+ , lgK1 = 3.04Ag+ + Cl- AgCl , lgK1 = 1.45Do o, can a ra mot khai niem e so sanh tng oi chnh xac o manh acid/base Lewis.

  • Acid Base cng, mem.Acid cng: Cation hoac phan t co kch thc nho, mat o ien tch dng cao, khong co kha nang cho e. Acid mem ngc lai.VD: Acid cng: H+, Ca2+, Al3+Acid mem: Cu+, Ag+, GaCl3Base cng: Ation hoac phan t co kch thc nho, kho b bien dang, khong co kha nang nhan e. Base mem ngc lai: Kch thc ln, de b phan cc, de b oxy hoa.VD: Base cng: F-, Cl-, OH-, NH3Base mem: I-, CN-, C2H4 Cac acid hay base cang kho cho-nhan e va cang kho bien dang th cang cng Co cac acid base khong cng, khong mem.

  • Quy tac phan ng: Cac acid cng de phan ng vi base cng tao cac hp chat ben, tng t cho cac acid/base mem.Chon mot acid hoac mot base lam chuan, xac nh o ben cac hp chat tao thanh cua no va cac acid/base khac e so sanh o cng.VD: Day base sau theo chieu giam dan o mem.Te2+>Se2+>S2->I->Br->O2->Cl->OH->CO32->NO3->SO42->F- (cng nhat)o cng tang dan trong day acid sau:Ag+
  • Acid - base cngpK1pK12pK123Al3+ F-7,1011,9815,83pK1234pK12345pK12345618,5320,2020,67Acid base mempK1pK12Cu+Cl-5,355,63Br-5,92I-8,85

  • 4. anh gia kha nang t xay ra cua phan ng acid - base bang o manh acid base cua chatNguyen tac anh gia: Tnh acid base cua cac chat tham gia phan ng cang khac xa nhau, phan ng cang de xay ra va xay ra cang hoan toan.o manh acid base cua chat phu thuoc vao: - Ban chat cua nguyen to tao acid hay base- So oxy hoa cua nguyen to tao acid hay base -Trang thai cau tao cua chat. - Moi trng xay ra phan ng.

  • a. anh gia o manh acid - base theo ban chat cua nguyen to tao acid hay base

    Nguyen to co tnh kim loai cang manh th hp chat cang co tnh base, nguyen to co tnh phi kim loai cang manh th hp chat cua no cang co tnh acid.

  • b. anh gia o manh acid - base theo mc o oxi hoa cua nguyen to tao acid hay base oi vi hp chat cung loai mot nguyen to, mc oxi hoa cua nguyen to tang th tnh acid cua hp chat tang. V du: So sanh tnh acid va tnh base cua day:MnO Mn2O3 MnO2 Mn2O5 MnO3 Mn2O7 MnO :Oxide base, tan de dang trong acid loang.Mn2O3 va MnO2: Oxide lng tnh, tnh acid va tnh base eu rat yeu. Mn2O7 : la anhidrit cua acid manh (HMnO4 ; pK = -2,3).

  • Viet phan ng minh hoa tren c s tnh acid base*V MnO co tnh base troi nen de tan trong dung dch acid loang:a) MnO(r) + 2HCl(dd) = MnCl2(dd) + H2O*V MnO2 co tnh base rat yeu nen ch tan cham trong acid ac nong:1b) MnO2(r) + 4HCl(ac, nong) = MnCl4(dd) + H2O Tuy nhien v ion Mn4+ la chat oxy hoa rat manh nen MnCl4 tiep tuc phan ng noi oxy hoa kh

  • 2b) MnCl4(dd) = MnCl2 + Cl2(k)Ket quab) MnO2(r) + 4HCl(ac, nong) = MnCl2(dd) + Cl2(k) + H2O*Mn2O7 la mot oxiacid manh do o no de dang phan ng vi nc cung nh vi dung dch base loang c) Mn2O7(r) + H2O(lanh) = 2HMnO4 (dd) d) Mn2O7(r) + 2NaOH(dd) = 2NaMnO4(dd) + H2O

  • c. anh gia o manh acid - base theo kha nang phan ng vi dung moi cua nguyen to tao acid hay base V du: Xet o manh cua Ca(OH)2 trong dung dch ncCa la kim loai kiem tho chu ky 4, phan nhom IIA, la kim loai rat manh, co o am ien 1,0, co the kh chuan (o) bang -2,76V, v vay co the d oan Ca(OH)2 la mot base manh ien ly hoan toan trong nc. Tuy nhien Ca(OH)2 ben vng (Go298 = -898kJ/mol; Ho298 = -986 kJ/mo)l nen o tan trong nc cua Ca(OH)2 nho: 0,1620 va 0,14830, v vay thc te Ca(OH)2 la mot base ch co o manh trung bnh. (Dung dch bao hoa canxi hydroxide 30oC co pH 9)

  • d. anh gia o manh acid - base theo moi trng xay ra phan ngSo sanh mc o thuy phan cua muoi nhom sulfat khi khong co va co mat ion floride (lay d)T (Al(OH)3) = 1.10-32, Kkb([AlF6]3-) = 1.10-20,67, KHF = 1.10-3,18 Khi khong co ion F-:Al3+.aq + 3H2O = Al(OH)3 + 3H+.aqKcb* = K3H2O/T(Al(OH)3) = 1.10-6 Khi co mat ion F-:[AlF6]3-.aq + 3H2O = Al(OH)3 + 3HF+ 6F-Kcb** = Kkb. K3H2O/T(Al(OH)3)K3HF = 1. 10-17,13Khi khong co ion F- , ion Al3+ thuy phan gap :Kcb*/Kc** = 1.10-6/1.10-17,13 = 1.1011,13 lan

  • IV. THUYET ACID-BASE USANOVICH VA LUX-FLOODThuyet UsanovichAcid la nhng chat co the cho i cation, ket hp vi anion, hoac e.Base la nhng chat co the cho i anion hoac e, ket hp vi cation.Moi tng tac eu co the xem la phan ng acid-base, ke ca phan ng co s trao oi e (p/ O-Kh).VD: Acid + Base BF3 + KF K+ + BF4-. AlF4 + NaF Na+ + [AlF6]-3.

  • Thuyet LuxBase la chat co kha nang cho i anion O2- con acid la chat co kha nang nhan anion O2-.VD: Acid Base SiO2 + CaO CaSiO3 CO2 + MgO MgCO3 S2O72-+ NO3- NO2+ + 2SO42-Thuyet Lux-Flood va Usanovich cho phep giai thch phan ng cua cac chat trang thai nong chay.VD: 3ZnO + P2O5 3Zn2+ + 2PO43- K2O + ZnO K+ + ZnO2-Ket luan: Cac thuyet acid-base khong mau thuan nhau ma ch khac nhau pham vi ng dung.

  • Phan ng ket hp: la phan ng tao chat phc tap hn t cac chat n gian hn.V du: CaO(r) + SiO2(r) = CaSiO3 (r)base acid NaOH(r) + CO2(k) NaHCO3(r) base acidPhan ng ket hp c xp vao phan ng acid base.