- Dieii die kim logi kiem: Dien phan mud'i clorua hoac hidroxit nong chaỵ Dien che kim logi kiem tho: Dien phan mu6'i clorua nong chaỵ
2.Dien phan dungdich
Khi dien phan dung dich (dung moi la nude), ngoai cac ion cua chat
dien phan tham gia qua trinh oxi hoa - khii b cac dien cue, con eo ion va
OH cua H2O va ban than kim loai lam dien cuẹ K h i do, d catot cation nao
CO tinh oxi hoa cang manh cang de bi khi( ; d anot anion nao c6 tinh khu cang manh cang de bi oxi hod.
a) Thit tu khi( d catot. Noi chung kim loai cang yéu thi cation kim loai do
CO tinh oxi hoa cang manh va cang de bi khir b catot (trijr trucmg hop ion H*). Thínudien phan Idn Imt la: H g ' \\^ Cú% H ^ Pb^^ Cac
ion kim loai kiem (Nâ K^), kiem th6 (Bâ^ C2i^\, AP^ khong bao
gid bi dien phan trong dung dich.
b) Thictuoxi hod danot. Anion nao c6 tinh khuf cang manh (cang de nhudng e)
se bi dien phan trudc.
Thvc tic dien phan Idn liMt la: I , Br , CI 0 H ~
Cac anion g6'c axit chiia oxi nhu SÔ", NO,, CO,"... kh6ng bi dien phan trong dung dich.
Thi du 1. Dien phan dung dich AgNO,:
Trong dung dich:
AgNO, -> Ag" + NO"
H 2 0^ H ^ + OH anot(+) NO; , OH" 4 0 H - - 4e -> 0 2 t + 2H2O (2H2O - 4e -> O2 + 4H^) (-) catot Ag^ 4Ag'' + 4e -> 4Ag
Phuang t r i n h diSn phan viét dang i o n :
4Ag^ + 2H2O ^ 4 A g 4 + O j t + 4H+
Phuang t r i n h dien phan viet dang phan tur:
4 A g N O , + 2H2O 4Ag4' + 0 2 t + 4HNO3
Thi du 2. V i e t cac phuang t r i n h phan irng dien phan xay ra k h i dien phan (vdri cue t r o , m a n g ngan x6'p) dung djch chiia a m o l C U S O 4 va b m o l NaCl trong 3 truorng hap: b = 2a, b < 2a va b > 2ạ
Hu&ng đn gidi: T r o n g d u n g djch: C U S O 4 - > Cú^ + SÔ- NaCl ^ Na* + Cl" H2O -> + OH - Giai doan 1: 6 c a t o t : Cu2^ + 2 e - ^ C u 4 (1) d a n o t : 2Cr - » C l , t + 2e (2) Cu^^ + 2cr-» C u i + C l 2 t
hoac: CUSO4 + 2NaCl ^ C u l + C l j t + Na2S04 (3) - N e u s6' m o l N a C l gap dOi s6' m o l CUSO4 (b = 2a) t h i sau (3) ca 2 chát
nay ,het, c h i con H2O tiép tuc bi dien phan:
2 H 2 0 - ^ , - ^ 2 H 2 t + 0 2 t
- Sau k h i phan ling (3) két thuc, néu t r o n g d u n g d i c h con CUSO4
(b < 2a), luc do tiép tuc qua t r i n h dien phan CUSO4 va HjO:
b catot: Cu^"" + 2e -> Cu
b anot: 2 H , 0 - 4e 0 , t + 4 H '
. 2 .1
2Cú^ + 2H2O 2 C u i + O j t + 4 H * (adsbygoogle = window.adsbygoogle || []).push({});
hoac: 2CUSO4 + 2 H 2 O- > 2Cu>l + 0 2 ^ + 2H2SO4
Khi het CUSO4 thi HjO tiép tuc bj dien phan: 2H2O - > 2 H 2 t + 0 2 t
- Sau phan ling (3), néu trong dung dich con NaCl (b > 2a), luc do se tiép tuc su dien phan NaCl nhu a thi du 2:
2NaCl + 2H2O > H j t + C l 2 t + 2 N a O H (Nude nguyen chát thuc té kh6ng bi dien phan).