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-




, , , , .

-1 , : - ( ).

 

1. , - , (, , ). .

:

+ + + + +

.

1.1. , :

+ + + + +

1.2. , , , , , . , Cr, , :

+5ē

-2ē

+ + + + +

2Cr+6 + 6 = 2Cr+3 () -

S-2 - 2 = S0 () -

1.3. ( ). () 3, 6 . , .

 

2Cr+6 + 6 = 2Cr+3 1

+

S-2 - 2 = S0 3

 


2Cr+6 +3S-2 = 2Cr+3 + 3 S0

1.4. . . , .

K2Cr2O7 + 3H2S + H2SO4 = Cr2(SO4)3 + 3S + K2SO4 + H2O

1.5. . (Cr2(SO4)3, K2SO4),

, 4 - (SO42-), , , 4. , 7:

 

K2Cr2O7 + 3H2S + 4H2SO4 = Cr2(SO4)3 + 3S + K2SO4 + 7H2O

 

, .

 

2. - ( ) , . (.. ) . .

1

()
(<7) + 2 2 -
( = 7) 2 + -
(>7) 2 - 2 -

 

.

2.1. :

K2Cr2O7 + H2S + H2SO4 → Cr2(SO4)3 + S + K2SO4 + H2O

2.2. - . , , . , (HCl, HNO3, H2SO4 .), (LiOH, NaOH, KOH .). , , - .

2K+ + Cr2O7-2 + H2S + 2 H+ + SO4-2 = 2Cr+3+3SO4-2 + S0 + 2K+ +SO4-2 + H2O

2.3. , :

Cr2O7-2 → 2Cr+3 H2S → S0

2.4. (. .1). 7 , 14 . 2 .

Cr2O7-2 + 14+ → 2Cr+3 + 72

H2S → S0 + 2+

2.5. . (+12), (+6), , - 6 . (0), (+2). 2 .

Cr2O7-2 + 14+ +6 → 2Cr+3 + 72

H2S - 2 → S0 + 2+

2.6. 3, .

Cr2O7-2 + 14+ +6 → 2Cr+3 + 72 1

+

H2S - 2 → S0 + 2+ 3

 

Cr2O7-2 + 14+ + 3H2S = 2Cr+3 + 72 + 3S0 + 6+

- , .

Cr2O7-2 + 8+ + 3H2S = 2Cr+3 + 72 + 3S0

:

K2Cr2O7 + 3H2S + 4H2SO4 = Cr2(SO4)3 + 3S + K2SO4 + 7H2O

. , :

I2 + HNO3 HIO3 +NO2 +H2O

HNO3 NO3- ( +).

- :

I2 + H+ + NO3- IO3- +NO2 +H2O

(..1) 10, :

 

NO3- + 2H+ +ēNO2 +H2O 10

I2 + 6H2O - 10ē 2IO3- + 12H+

10NO3- + 20 H+ + I2 + 6H2O10NO2 +10 H2O + 2 IO3- + 12H+

 

- :

10NO3- + 8 H+ + I2 10NO2 +4 H2O + 2 IO3-

 

. , NO3- H+ , , HNO3 , . . , :

I2 + 10HNO32HIO3 +10NO2 +4H2O

 

, , .

 





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