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Chng 6: OXI LU HUNH I. V TR, CU TO.

Cc nguyn t thuc PNC nhm VI gm 8O 16S 34Se 52Te 84Po c 6 electron ngoi cng

do d dng nhn 2e t cu hnh bn vng ca kh him. Vy tnh xiha l tnh cht ch yu.

Cu to nguyn t ca cc nguyn t nhm VIA .

- Ging nhau : u c 6e lp ngoi cng, c 2 c thn ( vit cu hnh e theo orbitan). s

oxiho -2 trong hp cht c m in nh hn ( kim loi, hir )

- Khc nhau: Tr O , cc nguyn t cn li S , Se, Te trng thi kch thch c th xut hin

4 hoc 6 e c thn iu ny gii thch s oxiho + 4 hoc + 6 ca S,Se,Te trong cc hp cht vi

cc nguyn t c m in ln hn ( oxi , flo )

- Ngoi tnh oxiho S,Se,Te cn c kh nng th hin tnh kh.

II. XI trong t nhin c 3 ng v O168 O17

8 O18

8 , Oxi l mt phi kim hot ng v l mt cht

xiha mnh v th trong tt c cc dng hp cht , oxi th hin s oxi ho 2 (tr : 1

22

21

2 , OHOF cc

peoxit 21

2 ONa ),duy tr s sng , s chy.

Tc dng hu ht vi kim loi (tr Au v Pt), cn c t0 to xit

2Mg + O2 ot 2MgO Magi oxit

4Al + 3O2 ot 2Al2O3 Nhm oxit

3Fe + 2O2 ot Fe3O4 Oxit st t (FeO, Fe2O3)

Tc dng hu ht vi phi kim (tr halogen), cn c t0 to ra oxit

S + O2 ot SO2

C + O2 ot

CO2

N2 + O2 ot

2NO t0 khong 30000C hay h quang in

Tc dng vi H2 (n mnh theo t l 2 :1 v s mol), t0

2H2 + O2 ot

2H2O

Tc dng vi cc cht c tnh kh.

2SO2 + O2 2 5,300OV O C

2SO3

CH4 + 2O2 ot

CO2 + 2H2O

Tc dng vi cc cht hu c.

C2H5OH + 3O2 2CO2 + 3H2O

C2H5OH + O2 lenmemgiam CH3COOH + H2O

III. ZN l dng th hnh ca oxi v c tnh xha mnh hn O2 rt nhiu

O3 + 2KI + H2O I2 + 2KOH + O2 (oxi khng c)

Do to ra KOH nn O3 lm xanh qu tm dd KI (dng trong nhn bit ozon)

2Ag + O3 Ag2O + O2 (oxi khng c phn ng)

IV. HIR PEOXIT : L cht c 2 kh nng l c tnh oxiho v c tnh kh.

Tnh oxiho: H2O2 + 2KI I2 + 2KOH

H2O2 + KNO2 KNO3 + H2O

Tnh kh : H2O2 + Ag2O 2Ag + O2 + H2O

5H2O2 + 2KMnO4 + 3H2SO4 K2SO4 + 2MnSO4 + 5O2 + 8H2O

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V. LU HUNH l cht xiha nhng yu hn O2, ngoi ra S cn ng vai tr l cht kh khi tc

dng vi oxi ( phn tch da trn dy s oxiho ca S )

S l cht oxiha khi tc dng vi kim loi v H2 to sunfua cha S2-

Tc dng vi nhiu kim loi (c t0,to sn phm ng s oxy ho thp ca kim loi)

Fe + S0

ot FeS-2

st II sunfua

Zn + S0

ot ZnS-2

km sunfua

Hg + S HgS-2

thy ngn sunfua, phn ng xy ra t0 thng

Tc dng vi H2: to hidro sunfua mi trng ung ( trng thi )

H2 + S ot H2S

-2 hidrosunfua

S l cht kh khi tc dng vi cht xiha to hp cht vi soh dng (+4, +6)

Tc dng vi phi kim (tr Nit v Iod)

S + O2 ot SO2 kh sunfur, lu hunh ixit, lu hunh (IV) xit.

S + 3F2 SF6

Ngoi ra khi gp cht xiha khc nh HNO3 to H2SO4

VI. HIDRSUNFUA (H2S) l cht kh mnh v trong H2S lu hunh c s oxi ho thp nht (-2),

tc dng hu ht cc cht xiha to sn phm ng vi soh cao hn.

Tc dng vi oxi c th to S hoc SO2 ty lng xi v cch tin hnh phn ng.

2H2S + 3O20t 2H2O + 2SO2 (d xi, t chy)

2H2S + O2thaptt 0 2H2O + 2S

(Dung dch H2S trong khng kh hoc lm lnh ngn la H2S ang chy)

Tc dng vi clo c th to S hay H2SO4 ty iu kin phn ng

H2S + 4Cl2 + 4H2O 8HCl + H2SO4

H2S + Cl2 2 HCl + S (kh clo gp kh H2S)

Dung dch H2S c tnh axit yu 2 nc : Khi tc dng dung dch kim c th to mui axit

hoc mui trung ho

H2S + NaOH 1:1 NaHS + H2O

H2S + 2NaOH 2::1 Na2S + 2H2O

VII. LU HUNH (IV) OXIT cng thc ha hc SO2, ngoi ra c cc tn gi khc l lu hunh

dioxit hay kh sunfur, hoc anhidrit sunfur.

Vi s oxi ho trung gian +4 (4

S O2). Kh SO2 va l cht kh, va l cht oxi ho v l

mt oxit axit.

SO2 l cht kh (4

S - 2e 6

S )

Khi gp cht oxi ho mnh nh O2, Cl2, Br2 : kh SO2 ng vai tr l cht kh.

24

S O2 + O2 2 5,300OV O C

2SO3

OS4

2 + Cl2 + 2H2O 2HCl + H2 OS6

4

5 OS4

2 + 2KMnO4 + 2H2O K2SO4 + 2MnSO4 + 2H2SO4

SO2 l cht oxi ho ( 4

S + 4e 0

S ) Khi tc dng cht kh mnh

OS4

2 + 2H2S 2H2O + 30

S

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OS4

2 + Mg MgO + S

Ngoi ra SO2 l mt oxit axit

SO2 + NaOH 1:1 NaHSO3 (

2nSO

nNaOH 2 )

SO2 + 2 NaOH 2:1 Na2SO3 + H2O (

2nSO

nNaOH 1)

Nu 1<

2nSO

nNaOH < 2 th to ra c hai mui molySONa

molxNaHSO

:

:

32

3

VIII. LU HUNH (VI) OXIT cng thc ha hc SO3, ngoi ra cn tn gi khc lu hunh tri

oxit, anhidrit sunfuric.

L mt xit axit

Tc dng vi H2O to axit sunfuric

SO3 + H2O H2SO4 + Q

SO3 tan v hn trong H2SO4 to leum : H2SO4.nSO3

Tc dng vi baz to mui

SO3 + 2 NaOH Na2SO4 + H2O

IX. AXT SUNFURIC H2SO4 trng thi long l mt axit mnh, trng thi c l mt cht

xiha mnh.

dng long l axt mnh lm qu tm, tc dng kim loi(trc H2) gii phng H2, tc

dng baz, oxit baz v nhiu mui.

H2SO4 2H+ + SO4

2- l qu tm ho mu .

H2SO4 + Fe FeSO4 + H2

H2SO4 + NaOH NaHSO4 + H2O

H2SO4 + 2NaOH Na2SO4 + 2H2O

H2SO4 + CuO CuSO4 + H2O

H2SO4 + BaCl2 BaSO4 + 2 HCl

H2SO4 + Na2SO3 Na2SO4 + H2O + SO2

H2SO4 + CaCO3 CaSO4 + H2O + CO2

dng c l mt cht xiha mnh

Tc dng vi kim loi: oxi ho hu ht cc kim loi (tr Au v Pt) to mui ho tr cao v

thng gii phng SO2 (c th H2S, S nu kim loi kh mnh nh Mg ).

2Fe + 6 H2SO4 0t Fe2(SO4)3+ 3SO2+ 6H2O

Cu + 2 H2SO4 0t CuSO4 + SO2+ 2H2O

Al, Fe, Cr khng tc dng vi H2SO4 c ngui, v kim loi b th ng ha.

Tc dng vi phi kim (tc dng vi cc phi kim dng rn, t0) to hp cht ca phi kim ng

vi s oxy ho cao nht

2H2SO4() + C 0t CO2 + 2SO2 + 2H2O

2H2SO4() + S 0t

3SO2 + 2H2O

Tc dng vi mt s cht c tnh kh.

FeO + H2SO4 () 0t Fe2(SO4)3 + SO2 + 4H2O

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2HBr + H2SO4 () 0t Br2 + SO2 + 2H2O

Ht nc ca mt s cht hu c.

C12H22O11 + H2SO4() 12C + H2SO4.11H2O

X. NHN BIT MT S CHT LIN QUAN.

1. MUI SUNFUA V NHN BIT GC SUNFUA (S2- ) hu nh cc mui sunfua iu khng

tan, ch c mui ca kim loi kim v kim th tan (Na2S, K2S, CaS, BaS). Mt s mui khng tan

v c mu c trng CuS en, PbS en, CdS vng, SnS gch, MnS hng.

nhn bit S2- dng dung dch Pb(NO3)2

Pb2+

+ S2-

PbS ( en, khng tan trong axit, nc)

2. MUI SUNFAT V NHN BIT GC SUNFAT (SO42-

)

C hai loi mui l mui trung ha (sunfat) v mui axit (hidrsunfat).

Phn ln mui sunfat tan, ch c BaSO4, PbSO4 khng tan c mu trng, CaSO4 t tan c

mu trng.

Nhn bit gc SO42-

(sunfat) dng dung dch cha Ba2+ , Ca2+ , Pb2+

Ba2+

+ SO42-

BaSO4 ( kt ta trng, khng tan trong nc v axit)

XI. IU CH

1. IU CH XI : 2KClO3 0t 2KCl + 3O2 (xc tc MnO2), iu ch trong PTN

Phn hu oxi gi hay nhit phn kalipemangenat

Trong CN chng ct phn on khng kh lng, in phn nc

( Vit cc ptp)

2. IU CH HIDRSUNFUA (H2S) :Cho FeS hoc ZnS tc dung vi dung dch HCl

FeS + 2HCl FeCl2 + H2S

t S trong kh hir

H2 + S 0t H2S

3. IU CH SO2 c rt nhiu phn ng iu ch

S + O2 0t

SO2

Na2SO3 + H2SO4() 0t

Na2SO4 + H2O + SO2

Cu +2H2SO4() 0t CuSO4 + 2H2O +SO2

4FeS2 + 11O2 0t

2Fe2O3 + 8SO2

t ZnS, FeS, H2S, S trong oxi ta cng thu c SO2.

4. IU CH SO3 : 2SO2 + O2 2 5,300OV O C

2 SO3 .

SO3 l sn phm trung gian iu ch axit sunfuric.

5. SN XUT AXIT SUNFURIC ( trong CN) T QUNG PYRIT ST FeS2

t FeS2 4FeS2 + 11O2 0t 2Fe2O3 + 8SO2

Oxi ho SO2 2SO2 + O2 2 5,300OV O C

2SO3

Hp nc: SO3 + H2O H2SO4

T LU HUNH

t S to SO2: S + O2 0t SO2

Oxi ho SO2 2SO2 + O2 2 5,300OV O C

2SO3

SO3 hp nc SO3 + H2O H2SO4