ÿþE l e k t r o c h e m i a z a d a n i a
1 . W z l e w c e z a w i e r a j c e j r o z t w ó r s i a r c z a n u ( V I ) c y n k u o s t |e n i u 0 , 2 m o l / d m 3 z a n u r z o n o b l a s z k c y n k o w .
P o d o b n i e w z l e w c e z a w i e r a j c e j r o z t w ó r s i a r c z a n u ( V I ) m i e d z i ( I I ) o s t |e n i u 0 , 1 m o l / d m 3 z a n u r z o n o b l a s z k
m i e d z i a n . T a k s k o n s t r u o w a n e p ó Bo g n i w a p o Bc z o n o k l u c z e m e l e k t r o l i t y c z n y m i z a m k n i t o w o b w ó d
e l e k t r y c z n y . 0 Z n / Z n 2 + = - 0 , 7 6 3 V ; 0 C u / C u 2 + = 0 , 5 2 1 V . ( T = 2 9 8 K )
a ) Z a p i s z s c h e m a t t e g o o g n i w a
b ) Z a p i s z r e a k c j e z a c h o d z c e w p ó Bo g n i w a c h i r e a k c j e s u m a r y c z n
c ) O b l i c z s i B e l e k t r o m o t o r y c z n t e g o o g n i w a .
d ) O b l i c z z m i a n e n t a l p i i s w o b o d n e j w t y m o g n i w i e , j e |e l i p r z e z o b w ó d p r z e p By n Bo 0 , 3 m o l a e l e k t r o n ó w .
2 . O b l i c z p o t e n c j a B e l e k t r o d y ( T = 2 9 8 K )
a ) s r e b r o w e j z a n u r z o n e j w 0 , 1 5 m o l o w y m r o z t w o r z e A g N O 3 . ( 0 A g / A g + = 0 , 7 9 9 V )
b ) c y n k o w e j z a n u r z o n e j w 1 0 - 2 m o l o w y m r o z t w o r z e Z n ( N O 3 ) 2 . ( 0 Z n / Z n 2 + = - 0 . 7 6 3 V )
c ) n i k l o w e j z a n u r z o n e j w 1 0 - 3 m o l o w y m r o z t w o r z e s o l i n i k l u ( I I ) . ( 0 N i / N i 2 + = - 0 . 2 5 0 V )
3 . Z b u d o w a n o o g n i w o z Bo |o n e z e l e k t r o d y s r e b r o w e j ( 0 A g / A g + = 0 , 7 9 9 V ) i e l e k t r o d y c y n k o w e j ( 0 Z n / Z n 2 + = -
0 , 7 6 3 V ) . W i e d z c , |e s t |e n i e j o n ó w s r e b r a w y n o s i Bo 5 · 1 0 - 6 m o l / d m 3 , a j o n ó w c y n k u 1 0 - 2 m o l / d m 3 ( T = 2 9 8
K ) :
a ) Z a p i s z s c h e m a t t e g o o g n i w a
b ) Z a p i s z r e a k c j e z a c h o d z c e w p ó Bo g n i w a c h i r e a k c j e s u m a r y c z n
c ) O b l i c z s i B e l e k t r o m o t o r y c z n t e g o o g n i w a .
d ) O b l i c z z m i a n e n t a l p i i s w o b o d n e j w t y m o g n i w i e , j e |e l i p r z e z o b w ó d p r z e p By n Bo 0 , 1 m o l a e l e k t r o n ó w .
4 . Z b u d o w a n o o g n i w o w t e n s p o s ó b , |e : w r o z t w o r z e o s t |e n i u 0 , 6 m o l / d m 3 w z g l d e m j o n ó w S n 4 + i 0 , 1
m o l / d m 3 w z g l d e m j o n ó w S n 2 + z a n u r z o n o e l e k t r o d p l a t y n o w . P o d o b n i e w d r u g i m r o z t w o r z e o s t |e n i u 0 , 4
m o l / d m 3 w z g l d e m j o n ó w F e 3 + i 0 , 0 4 m o l / d m 3 w z g l d e m j o n ó w F e 2 + z a n u r z o n o e l e k t r o d p l a t y n o w .
R o z t w o r y p o Bc z o n o k l u c z e m e l e k t r o l i t y c z n y m i z a m k n i t o o b w ó d e l e k t r y c z n y . 0 S n 4 + / S n 2 + = 0 , 1 5 0 V ;
0 F e 3 + / F e 2 + = 0 , 7 7 1 V , T = 2 9 8 K
a ) Z a p i s z s c h e m a t t e g o o g n i w a
b ) Z a p i s z r e a k c j e z a c h o d z c e w p ó Bo g n i w a c h i r e a k c j e s u m a r y c z n
c ) O b l i c z s i B e l e k t r o m o t o r y c z n t e g o o g n i w a .
d ) O b l i c z z m i a n e n t a l p i i s w o b o d n e j w t y m o g n i w i e , j e |e l i p r z e z o b w ó d p r z e p By n Bo 0 , 2 5 m o l a e l e k t r o n ó w .
5 . Z b u d o w a n o o g n i w o w t e n s p o s ó b , |e : W k w a [n y m r o z t w o r z e m a n g a n i a n u ( V I I ) , w k t ó r y m j o n y M n O 4 - s w
r ó w n o w a d z e z j o n a m i M n 2 + z a n u r z o n o e l e k t r o d p l a t y n o w . S t |e n i e j o n ó w M n O 4 - w y n o s i Bo 0 , 0 8 m o l / d m 3 , a
j o n ó w M n 2 + 0 , 0 4 m o l / d m 3 . P o d o b n i e w d r u g i m p ó Bo g n i w i e w r o z t w o r z e z a w i e r a j c y m j o n y F e 3 + ( 0 , 6
m o l / d m 3 ) i F e 2 + ( 0 , 0 4 m o l / d m 3 ) z a n u r z o n o e l e k t r o d p l a t y n o w . R o z t w o r y p o Bc z o n o k l u c z e m
e l e k t r o l i t y c z n y m i z a m k n i t o o b w ó d e l e k t r y c z n y . 0 M n O 4 - / M n 2 + = 1 , 5 1 V ; 0 F e 3 + / F e 2 + = 0 , 7 7 1 V , T = 2 9 8 K
a ) Z a p i s z s c h e m a t t e g o o g n i w a
b ) Z a p i s z r e a k c j e z a c h o d z c e w p ó Bo g n i w a c h i r e a k c j e s u m a r y c z n
c ) O b l i c z s i B e l e k t r o m o t o r y c z n t e g o o g n i w a .
d ) O b l i c z z m i a n e n t a l p i i s w o b o d n e j w t y m o g n i w i e , j e |e l i p r z e z o b w ó d p r z e p By n Bo 0 , 5 m o l a e l e k t r o n ó w .
6 . C z y z a j d n a s t p u j c e r e a k c j e :
a ) C o + Z n S O 4 ( 0 = - 0 , 2 7 7 V 0 = - 0 , 7 6 3 V )
,
C o / C o 2 + Z n / Z n 2 +
b ) C o S O 4 + Z n ( 0 = - 0 , 2 7 7 V , 0 = - 0 , 7 6 3 V )
C o / C o 2 + Z n / Z n 2 +
c ) A g + H C l ( 0 = 0 , 7 9 9 V , 0 = 0 , 0 0 0 V )
A g / A g + H 2 / 2 H +
d ) F e + C u S O 4 ( 0 = - 0 , 4 4 0 V , 0 = 0 , 3 4 5 V )
+ +
F e / F e 2 C u / C u 2
R o z w i z a n i a
Z a d . 1 .
0 Z n / Z n 2 + = - 0 , 7 6 3 V
0 C u / C u 2 + = 0 , 3 4 5 V
C Z n S O 4 = 0 , 2 m o l / d m 3 Ò! [ Z n 2 + ] = 0 , 2 m o l / d m 3
C C u S O 4 = 0 , 1 m o l / d m 3 Ò! [ C u 2 + ] = 0 , 1 m o l / d m 3
T = 2 9 8 K
a ) P o n i e w a | p o t e n c j a B s t a n d a r d o w y e l e k t r o d y c y n k o w e j ( 0 Z n / Z n 2 + ) j e s t n i |s z y n i | p o t e n c j a B s t a n d a r d o w y
e l e k t r o d y m i e d z i o w e j ( 0 C u / C u 2 + ) ; e l e k t r o d a c y n k o w a b d z i e a n o d , a m i e d z i o w a k a t o d .
S c h e m a t :
Z n õøZ n 2 + õøõø C u 2 + õøC u
b ) N a a n o d z i e z a c h o d z i p r o c e s u t l e n i a n i a , a n a k a t o d z i e r e d u k c j i
A ( - ) Z n - 2 e ’! Z n 2 +
K ( + ) C u 2 + + 2 e ’! C u
Z n + C u 2 + ’! Z n 2 + + C u
c )
I s p o s ó b o b l i c z a n i a s i By e l e k t r o m o t o r y c z n e j - E ( S E M ) :
Z a l e |n o [ p o m i d z y s t |e n i e m j o n ó w w r o z t w o r z e , a p o t e n c j a Be m e l e k t r o d y o k r e [l a r ó w n a n i e N e r n s t a :
R T [ f . z r e d ]
= 0 - l n
n F [ f . u t l ]
g d z i e :
R - s t a Ba g a z o w a = 8 , 3 1 4 J / m o l Å"K
T t e m p e r a t u r a
F s t a Ba F a r a d a y a = 9 6 5 0 0 C / m o l
n l i c z b a w y m i e n i a n y c h e l e k t r o n ó w
[ f . z r e d ] s t |e n i e f o r m y z r e d u k o w a n e j
[ f . u t l ] s t |e n i e f o r m y u t l e n i o n e j
W i e d z c , |e : l n x = 2 , 3 0 3 l o g x
R ó w n a n i e N e r n s t a p r z y j m u j e p o s t a :
2 , 3 0 3 R T [ f . z r e d ]
= 0 - l o g
n F [ f . u t l ]
W w a r u n k a c h s t a n d a r d o w y c h ( T = 2 9 8 K ) :
2 , 3 0 3 Å"8 , 3 1 4 Å" 2 9 8 [ f . z r e d ]
= 0 - l o g
n Å" 9 6 5 0 0 [ f . u t l ]
0 , 0 5 9 [ f . z r e d ]
= 0 - l o g
n [ f . u t l ]
Z a t e m :
0 , 0 5 9 [ Z n ]
( A ) = 0 - l o g
Z n / Z n 2 +
2 [ Z n 2 + ]
0 , 0 5 9 1
= - 0 , 7 6 3 - l o g = - 0 , 7 8 4 V
2 0 , 2
0 , 0 5 9 [ C u ]
( K ) = 0 - l o g
C u / C u 2 +
2 [ C u 2 + ]
0 , 0 5 9 1
= 0 , 3 4 5 - l o g = 0 , 3 1 6 V
2 0 , 1
S i Ba e l e k t r o m o t o r y c z n a E ( S E M ) - r ó |n i c a p o t e n c j a Bó w w n i e p r a c u j c y m o g n i w i e .
E = K - A
E = 0 , 3 1 6 ( - 0 , 7 8 4 ) = 1 , 1 V
I I s p o s ó b o b l i c z a n i a s i By e l e k t r o m o t o r y c z n e j - E ( S E M ) :
P o t e n c j a B t e r m o d y n a m i c z n y w y r a |a s i w z o r e m :
"G = "G 0 + R T l n K
W w a r u n k a c h i z o t e r m i c z n o - i z o b a r y c z n y c h e n t a l p i a s w o b o d n a ( "G ) j e s t r ó w n a p r a c y e l e m e n t a r n e j , k t ó r a w
p r z y p a d k u o g n i w a j e s t p r a c e l e k t r y c z n ( W e l = - n F E )
"G = W e l = - n F E
g d z i e :
F s t a Ba F a r a d a y a = 9 6 5 0 0 C / m o l
n l i c z b a w y m i e n i a n y c h e l e k t r o n ó w
E s i Ba e l e k t r o m o t o r y c z n a o g n i w a
"G 0 = - n F E 0
P o p o d s t a w i e n i u :
- n F E = - n F E 0 + R T l n K / ( - n F )
R T
E = E 0 - l n K
n F
W i e d z c , |e : l n x = 2 , 3 0 3 l o g x
R ó w n a n i e p r z y j m u j e p o s t a :
2 , 3 0 3 R T
E = E 0 - l o g K
n F
W w a r u n k a c h s t a n d a r d o w y c h ( T = 2 9 8 K ) :
2 , 3 0 3 Å"8 , 3 1 4 Å" 2 9 8
E = E 0 - l o g K
n Å" 9 6 5 0 0
0 , 0 5 9
E = E 0 - l o g K
n
g d z i e :
0
E 0 j e s t r ó |n i c p o t e n c j a Bó w s t a n d a r d o w y c h e l e k t r o d ( E = 0 - 0 )
K A
K - j e s t s t a B r ó w n o w a g i d l a s u m a r y c z n e j r e a k c j i z a c h o d z c e j w o g n i w i e
W a n a l i z o w a n y m o g n i w i e z a c h o d z i n a s t p u j c a r e a k c j a s u m a r y c z n a :
Z n + C u 2 + ’! Z n 2 + + C u
Z a t e m :
[ Z n 2 + ] [ C u ] [ Z n 2 + ]
K = =
[ Z n ] [ C u 2 + ] [ C u 2 + ]
0 . 0 5 9 [ Z n 2 + ]
E = 0 - 0 - l o g
2 + 2 +
C u / C u Z n / Z n
2 [ C u 2 + ]
0 . 0 5 9 0 , 2
E = 0 , 3 4 5 - ( - 0 , 7 6 3 ) - l o g = 1 , 1 V
2 0 , 1
d )
"G = - n F E
"G = - 0 , 3 Å"9 6 5 0 0 Å"1 , 1 = - 3 1 8 4 5 J = - 3 1 , 8 4 5 k J
j e d n o s t k a
C C J
m o l Å" Å"V = m o l Å" Å" = J
m o l m o l C
Z a d . 2 .
0 , 0 5 9 [ f . z r e d ]
= 0 - l o g
n [ f . u t l ]
0 , 0 5 9 [ A g ] 1
a ) = 0 - l o g = 0 , 7 9 9 - 0 , 0 5 9 l o g = 0 , 7 5 0 V
+
A g / A g
1 [ A g + ] 0 , 1 5
0 , 0 5 9 [ Z n ] 1
b ) = 0 - l o g = - 0 , 7 6 3 - 0 , 0 2 9 5 l o g = - 0 , 8 2 2 V
2 +
Z n / Z n
2 [ Z n 2 + ] 0 , 0 1
0 , 0 5 9 [ N i ] 1
c ) = 0 - l o g = - 0 , 2 5 0 - 0 , 0 2 9 5 l o g = - 0 , 3 3 8 5 V
2 +
N i / N i
2 [ N i 2 + ] 0 , 0 0 1
Z a d . 3 .
0 Z n / Z n 2 + = - 0 , 7 6 3 V
0 A g / A g + = 0 , 7 9 9 V
[ Z n 2 + ] = 1 0 - 2 m o l / d m 3
[ A g + ] = 5 Å"1 0 - 6 m o l / d m 3
T = 2 9 8 K
a )
Z n õøZ n 2 + õøõø A g + õøA g
b )
A ( - ) Z n - 2 e ’! Z n 2 +
K ( + ) 2 A g + + 2 e ’! 2 A g
Z n + 2 A g + ’! Z n 2 + + 2 A g
c )
I s p o s ó b :
0 , 0 5 9 [ Z n ] 1
( A ) = 0 - l o g = - 0 , 7 6 3 - 0 , 0 2 9 5 l o g = - 0 , 8 2 2 V
2 +
Z n / Z n
2 [ Z n 2 + ] 0 , 0 1
0 , 0 5 9 [ A g ] 2 1
( K ) = 0 - l o g = 0 , 7 9 9 - 0 , 0 2 9 5 l o g = 0 , 4 8 6 V
A g / A g +
2 [ A g + ] 2 ( 5 Å"1 0 - 6 ) 2
E = K - A = 0 , 4 8 6 - ( - 0 , 8 2 2 ) = 1 , 3 0 8 V
I I s p o s ó b :
0 , 0 5 9
E = E 0 - l o g K
n
0 , 0 5 9 [ Z n 2 + ] [ A g ] 2 0 , 0 5 9 [ Z n 2 + ]
E = 0 - 0 - l o g = 0 - 0 - l o g
2 +
A g / A g + Z n / Z n
2 [ Z n ] [ A g + ] 2 A g / A g + Z n / Z n 2 + 2 [ A g + ] 2
1 0 - 2
E = 0 , 7 9 9 - ( - 0 , 7 6 3 ) - 0 , 0 2 9 5 l o g = 1 , 3 0 8 V
( 5 Å"1 0 - 6 ) 2
d )
"G = - n F E
"G = - 0 , 1 Å"9 6 5 0 0 Å"1 , 3 0 8 = - 1 2 6 2 2 , 2 J = - 1 2 , 6 2 2 k J
Z a d . 4 .
[ S n 4 + ] = 0 , 6 m o l / d m 3
[ S n 2 + ] = 0 , 1 m o l / d m 3
[ F e 3 + ] = 0 , 4 m o l / d m 3
[ F e 2 + ] = 0 , 0 4 m o l / d m 3
0 = 0 , 1 5 0 V
S n 4 / S n 2 +
0 = 0 , 7 7 1 V
3 + / 2 +
F e F e
T = 2 9 8 K
a )
P t õøS n 2 + , S n 4 + õøõø F e 3 + , F e 2 + õøP t
b )
A ( - ) S n 2 + - 2 e - ”! S n 4 +
K ( + ) 2 F e 3 + + 2 e - ”! 2 F e 2 +
S n 2 + + 2 F e 3 + ”! S n 4 + + 2 F e 2 +
c ) I s p o s ó b :
0 , 0 5 9 [ f . z r e d ]
= 0 - l o g
n [ f . u t l ]
0 , 0 5 9 [ S n 2 + ] 0 , 1
( A ) = 0 - l o g = 0 , 1 5 0 - 0 , 0 2 9 5 l o g = 0 , 1 7 3 V
4 + 2 +
S n / S n
2 [ S n 4 + ] 0 , 6
0 , 0 5 9 [ F e 2 + ] 2 ( 0 , 0 4 ) 2
( K ) = 0 - l o g = 0 , 7 7 1 - 0 , 0 2 9 5 l o g = 0 , 8 3 0 V
3 + 2 +
F e / F e
2 [ F e 3 + ] 2 ( 0 , 4 ) 2
E = K - A = 0 , 8 3 0 - 0 , 1 7 3 = 0 , 6 5 7 V
I I s p o s ó b :
0 , 0 5 9
E = E 0 - l o g K
n
0 , 0 5 9 [ S n 4 + ] [ F e 2 + ] 2
E = 0 - 0 - l o g
3 + 2 + 4 + 2 +
F e / F e S n / S n
2 [ S n 2 + ] [ F e 3 + ] 2
0 , 6 Å" ( 0 , 0 4 ) 2
E = 0 , 7 7 1 - 0 , 1 5 0 - 0 , 0 2 9 5 l o g = 0 , 6 5 7 V
0 , 1 Å" ( 0 , 4 ) 2
d )
"G = - n F E
"G = - 0 , 2 5 Å"9 6 5 0 0 Å"0 , 6 5 7 = - 1 5 8 5 0 , 1 J = - 1 5 , 8 5 0 k J
Z a d . 5 .
-
[ M n O 4 ] = 0 , 0 8 m o l / d m 3
[ M n 2 + ] = 0 , 0 4 m o l / d m 3
[ F e 3 + ] = 0 , 6 m o l / d m 3
[ F e 2 + ] = 0 , 0 4 m o l / d m 3
0 = 1 , 5 1 V
2 +
M n O - / M n
4
0 = 0 , 7 7 1 V
3 + / 2 +
F e F e
T = 2 9 8 K
a )
P t õøF e 2 + , F e 3 + õøõø M n O 4 - , M n 2 + õøP t
b )
A ( - ) 5 F e 2 + - 5 e - ”! 5 F e 3 +
K ( + ) M n O 4 - + 8 H + + 5 e - ”! M n 2 + + 4 H 2 O
5 F e 2 + + M n O 4 - + 8 H + ”! 5 F e 3 + + M n 2 + + 4 H 2 O
c ) I s p o s ó b :
0 , 0 5 9 [ f . z r e d ]
= 0 - l o g
n [ f . u t l ]
0 , 0 5 9 [ F e 2 + ] 5 ( 0 , 0 4 ) 5
( A ) = 0 - l o g = 0 , 7 7 1 - 0 , 0 1 1 8 l o g = 0 , 8 4 0 V
3 + 2 +
F e / F e
5 [ F e 3 + ] 5 ( 0 , 6 ) 5
0 , 0 5 9 [ M n 2 + ] 0 , 0 4
( K ) = 0 - l o g = 1 , 5 1 - 0 , 0 1 1 8 l o g = 1 , 5 1 4 V
2 +
M n O - / M n
4
5 [ M n O 4 - ] 0 , 0 8
E = K - A = 1 , 5 1 4 - 0 , 8 4 0 = 0 , 6 7 4 V
I I s p o s ó b :
0 , 0 5 9
E = E 0 - l o g K
n
0 , 0 5 9 [ M n 2 + ] [ F e 3 + ] 5
E = 0 - 0 - l o g
3 + 2 + 2 +
-
F e / F e M n O - / M n
4
5 [ M n O 4 ] [ F e 2 + ] 5
0 , 0 4 Å" ( 0 , 6 ) 5
E = 1 , 5 1 - 0 , 7 7 1 - 0 , 0 1 1 8 l o g = 0 , 6 7 4 V
0 , 0 8 Å" ( 0 , 0 4 ) 5
d )
"G = - n F E
"G = - 0 , 5 Å"9 6 5 0 0 Å"0 , 6 7 4 = - 3 2 5 2 0 , 5 J = - 3 2 , 5 2 0 k J
Z a d . 6 .
a ) C o + Z n S O 4
0 = - 0 , 2 7 7 V 0 = - 0 , 7 6 3 V
,
C o / C o 2 + Z n / Z n 2 +
0 = - 0 , 2 7 7 V > 0 = - 0 , 7 6 3 V
2 + 2 +
C o / C o Z n / Z n
r e d u k c j a u t l e n i a n i e
Z n - 2 e ”! Z n 2 +
C o 2 + + 2 e ”! C o
Z n + C o 2 + ”! Z n 2 + + C o
C z y l i r e a k c j a C o + Z n S O 4 n i e z a j d z i e
b ) C o S O 4 + Z n ( 0 = - 0 , 2 7 7 V , 0 = - 0 , 7 6 3 V ) - t a k
2 + 2 +
C o / C o Z n / Z n
c ) A g + H C l ( 0 = 0 , 7 9 9 V , 0 = 0 , 0 0 0 V ) n i e z a j d z i e
A g / A g + H / 2 H +
2
d ) F e + C u S O 4 ( 0 = - 0 , 4 4 0 V , 0 = 0 , 3 4 5 V ) - t a k
2 + 2 +
F e / F e C u / C u
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