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Bi 27: NHM VMT S HP CHT CA NHM

A. NHM

I. V tr v cu to

1. V tr

Nhm c s hiu nguyn t 13, thuc chu k 3, nhm IIIA, chu k 3 ca bng HTTH

2. Cu to ca nhm

- Cu hnh e: 1s22s22p63s23p1 hay [Ne]3s23p1 .

- S oxi ho: +3.

II. Tnh cht vt l

Almu trng bc, mm, d ko si v dt mng, nh (2,7g/cm3), t0nc = 6600C, dn in

v nhit tt.

III. Tnh cht ha hc

Nhm l kim loi c tnh kh mnh sau kim loi kim v kim th.

Al Al3+ + 3e

1. Tc dng vi phi kim

Tc dng trc tip v mnh vi nhiu phi kim nh: O2, Cl2, S,

V d: Al + O2o

t

Al2O3

2. Tc dng vi axit HCl v H2SO4 long H2:

2Al + 6HCl 2AlCl3 + 3H2

2Al + 6H+ 2Al3+ + 3H2

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Vi HNO3 long hoc c nng, H2SO4 c nng th nhm kh v xung s oxi ho thp

hn.

Al + 4HNO3 long Al(NO3)3 + NO + 2H2O

2Al + 6H2SO4 c, nng Al2(SO4)3 + 3SO2+ 6H2O

- Vi HNO3 v H2SO4 c ngui: khng tc dng .

4. Tc dng vi nc

Nhm c th kh c nc H2: 2Al + 6H2O 2Al(OH)3 + 3H2

Nhng vt bng nhm c ph mng Al2O3 rt mng, mn, bn nn khng cho nc v

kh thm qua.

5. Tc dng vi dung dch kim.

Nhm tan trong dung dch kim : 2Al + 2NaOH + 2H2O 2NaAlO2 (dd) + 3H2

Hin tng trn c gii thch nh sau:

- Mng bo v Al2O3 b ph hy trong dung dch kim:

Al2O3 + 2NaOH 2NaAlO2+ 2H2O

- Nhm kh nc: 2Al + 6H2O 2Al(OH)3 +3H2

- Mng Al(OH)3 b ph hy: Al(OH)3 + NaOH 2NaAlO2 (dd) + 3H2

IV. ng dng v sn xut.

1. ng dng

- Ch to my bay, t, tn la, tu v tr, trang tr ni tht, bt nhm trn bt

st( tecmit) dng hn ng ray.

2. Sn xut

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- Trong cng nghip, nhm c sn xut t qung boxit bng phng php in phn.

C 2 cng on:Tinh ch qung boxit(Al2O3.2H2O): loi b tp cht SiO2, Fe2O3in

phn Al2O3 nng chy( hn hp Al2O3 vi criolit Na3AlF6):2Al2O3 4Al + 3O2

B. MT S HP CHT QUAN TRNG CA NHM

I. NHM OXIT Al2O3

1. L tnh

Trng thi rn, mu trng, khng tc dng vi nc va khng tan trong nc, t 0nc

20500C.

2. Trng thi t nhin: tn ti 2 dng

- Dng ngm nc: boxit (Al2O3.nH2O) sn xut nhm

- Dng khan: emery c cng cao dng lm mi

3. Tnh cht ho hc :

a. Tnh bn vng: Lc ht gia Al3+ v O2- rt mnh to ra lin kt bn vng c t0nc rt

cao, kh b kh thnh kim loi nhm.

b.Tnh lng tnh

- Tnh baz : Al2O3 + 6HCl 2 AlCl3 + 3 H2O

Al2O3 + 6H+ 2Al3+ + 3 H2O

- Tnh axit : Al2O3 + 2 NaOH 2NaAlO2+ 3 H2O

Al2O3 + 2OH- 2 AlO2-+2H2O

4.ng dngLm trang sc, cng nghip k thut cao, vt liu mi ( mi ), nguyn

liu sn xut nhm kim loi

II. NHM HiROXIT Al(OH)3

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1. Tnh cht vt l: Cht rn, kt ta keo, mu trng

2. Tnh cht ho hc

a. Hp cht km bn :D b phn hu bi nhit

Al(OH)3o

t

Al2O3 + H2O

b. L hp cht lng tnh

* Tnh baz : Al(OH)3 + 3 HCl AlCl3 + 3H2O

Al(OH)3 + 3H+ Al3+ + 3H2O

* Tnh axit :

Al(OH)3 + NaOH NaAlO2+ 2H2O Al(OH)3 + OH- AlO2-+2H2O

Al(OH)3 l hiroxit lng tnh

III. NHM SUNFAT

Phn chua K2SO4. Al2(SO4)3 .24H2O. vit gn: KAl(SO4)2.12H2O

Nu thay K+ bng Na+, Li+ hay NH4+ mui kp khc (phn nhm)

Phn chua c s dng trong thuc da, cng nghip giy, cht cm mu, lm trong

nc.

IV. CCH NHN BIT ION Al3+ TRONG DUNG DCH

- Cho t t dung dch NaOH n d th kt ta keo ri kt ta tan to dung dch Al3+.

Al3+ + 3OH- Al(OH)3

Al(OH)3 + OH- d AlO2-+2H2O

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