ใบความรู้ที่ 6 ...

5

6 1.

2

1. (Primary cell)

2. (Secondary cell Reversible cell)

- 1 ()() 1

-Zn

Fe

Cd

Cd

Pd

Zn (Hg)

Zn (Hg)

LiMnO2NiO2NiO2Ag2O AgO

PbO2HgO

MnO2MnO2NH4Cl - ZnCl2KOH

KOH

KOH

H2SO4KOH-ZnO

KOH

KOH0.9 - 1.4

1.2 - 1.4

1.1 - 1.3

1.0 - 1.1

1.95 - 2.04

1.30

0.9 - 1.2

3.4

1.1 (Dry cell)

2

1. (Acidic dry cells)

2. (Alkaline dry cells)

. flash ( Leclanche cell) Georges Leclanche .. 1866

1.5 0.8 1.3

1

1 2 () (NH4Cl) (IV) (IV) +4 MnO2 +3 Mn2O3

() Zn ; Zn (s) ( Zn2+ (aq) + 2e-

E0 = +0.763 V

() ;

MnO2 (s) + 2NH4+ (aq) + 2e- ( Mn2O3 (s) + 2NH3 (g) + H2O (l) E0 = +0.50 V

;

Zn(s) + MnO2 (s) + 2NH4+ (aq)(Zn2+ (aq) + Mn2O3 (s) + 2NH3 (g) + H2O (l) ;

= 1.26 V

(250 C 1 atm) 1.5

[ Zn(NH3)4]2+

Zn2+ (aq) + 4NH3 (g) ( [ Zn(NH3)4]2+(aq)

Polarization

(0.0666 kwh/kg)

. (Alkaline dry cells) OH- (Paste) (IV) 1.54

; Zn(s) + 2OH- (aq) ( ZnO (s) + H2O (l) + 2e-

; 2MnO2 (s) + H2O (l) + 2e- ( Mn2O3 (s) + 2OH- (aq)

Zn(s) + 2MnO2 (s) ( Zn(OH)2 (s) + Mn2O3 (s)

2

. ( Mercury cell) - (Rubin - mallory cell) MnO2 HgO ( (II) ) 1.35

; Zn (s) + 2OH- (aq) ( ZnO (s) + H2O (l) + 2e- , E0 = 1.25 V

; HgO (s) + H2O (l) + 2e- ( Hg (l) + 2OH- (aq), E0 = 0.098 V

; Zn (s) + HgO (s) ( ZnO (s) + Hg (l) ,

= 1.35 V

3

. (Zinc-silver oxide cell Button Battery) AgO MnO2 1.58 V

; Zn (s) + 2OH- (aq) ( ZnO (s) + H2O (l) + 2e- , E0 = 1.25 V

; 2AgO (s) + H2O (l) + 2e- ( Ag2O (s) + 2OH- (aq) , E0 = 0.61 V

; Zn (s) + 2AgO (s) ( ZnO (s) + Ag2O (s) ,

= 1.86 V

(II) (I) (Ag2O) (Ag)

Zn (s) + Ag2O (s) + H2O (l) ( Zn(OH)2 (s) + 2Ag (s) , E0 = 1.58 V

4 1.2. (Secondary cell Reversible cell)

(Charging Recharging) -

. (Lead storage battery) (0.022 Kwh/kg) 6 12 (IV) (PbO2) 40% ( 5.3 mol/dm3 ) 1.3 1.1

5

; Pb (s) + SO42- (aq) ( PbSO4 (s) + 2e- , E0 = +0.356 V

; PbO2 (s) + 4H+ (aq) + SO42- (aq) + 2e- ( PbSO4 (s) + 2H2O (l) , E0 = +1.685 V

Pb (s) + PbO2 (s) + 4H+ (aq) + 2SO42- (aq) ( 2PbSO4 (s) + 2H2O (l) ,

= +2.041 V

PbSO4 () Pb 2 (H2SO4) 5.3 mol / dm3 1.

6

(Pb)

A (Anode) (IV) (PbO2) Pb Pb PbO2 ()

(1) Pb (s) ( Pb2+ (aq) + 2e-

(2) Pb2+ (aq) + 2H2O (l) ( PbO2 (s) + 4H+ (aq) + 2e-

; Pb(s) + 2H2O (l) ( PbO2 (s) + 4H+ (aq) + 4e- ()

B (Cathode) H2 Pb H+ H2

2H+ (aq) + 2e- ( H2 (g)

2.

7

17.7 B A

B Pb Pb2+ SO42- PbSO4 B Anode

(1) Pb(s) ( Pb2+ (aq) + 2e-

(2) Pb2+ (aq) + SO42+ (aq) ( PbSO4 (s)

; Pb (s) + SO42- (aq) ( PbSO4 (s) + 2e-

.. (3)

B PbO2 Pb PbO2 H+ Pb2+ H2O Pb2+ SO42- PbSO4 A Cathode

(4) PbO2 (s) + 4H+ (aq) + 2e- ( Pb2+ (aq) + 2H2O (l)

(5) Pb2+ (aq) + SO42- (aq) ( PbSO4 (s)

; PbO2 (s) + 4H+ (aq) + SO42- (aq) + 2e- ( PbSO4 (s) + 2H2O (l) (6)

(3) + (6)

Pb (s) + PbO2 (s) + 4H+ (aq) + 2 SO42- (aq) ( 2PbSO4 (s) + 2H2O (l)

3. 2

2

2

A Anode

PbSO4 (s) + 2H2O (l) ( PbO2 (s) + 4H+ (aq) + 2e-

B Cathode

PbSO4 (s) + 2e- ( Pb (s) + SO42- (aq)

2

2PbSO4 (s) + 2H2O (l) ( Pb(s) + PbO2 (s)+4H+ (aq) + 2SO42- (aq)

Pb(s) + PbO2 (s)+4H+ (aq) + 2SO42- (aq) 2PbSO4 (s) + 2H2O (l)

2

Pb- - - - - -

PbO2- - - - - -

1.

2.

3. 2 , 3 ,

4.

5.

= +2.041 V 6 12 V

6.

Pb , PbO2 , H2SO4PbSO4 , H2O

PbSO4 , H2OPb , PbO2 , H2SO4

7. H2SO4 40% 1.3 H2SO4 1.10

8. H2SO4

. - (Nickel - Cadmium cell) (Nicad cell)

8 -

- (IV)

; Cd (s) + 2OH- (aq) ( Cd (OH)2 (s) + 2e-

, E0 = 0.81 V

; NiO2 (s) + 2H2O (l) + 2e- ( Ni(OH)2 (s) + 2OH- (aq), E0 = 0.49 V

; Cd (s) + NiO2 (s) + 2H2O (l) ( Cd (OH)2 (s) + Ni(OH)2 (s) ,

= +1.30 V

Polarization 1.30 V 3 - -

2.041 V1.30 V

()

()Pb

PbO2Cd

NiO2

H2SO4 KOH NaOH

(((((((((((((((((((((((((

_992120431.unknown

_992122490.unknown

_992126379.unknown

_992127418.unknown

_992120914.unknown

_992120006.unknown