, , , , .
-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
, , .