PRACTISE QUESTIONS ELECTROCHEMISTRY
1
For the Galvanic cell,
Ag | AgCl(s) | KCl (0.2 M) || KBr (0.001 M) | AgBr(s) | Ag Calculate the emf generated and assign correct polarity to each electrode for a spontaneous process after taking into account the cell at 25 °C '10 '1 G!"# K s$ K s$ s$(AgCl) % 2.& × 10 s$ (AgBr) % . × 10 1.
AgCl Ag* * Cl ' K s$ +Ag*, +Cl ' , s$(AgCl) % sp # $gCl" 2! ×10 −10 * = = 14 × 10 −& M ∴+Ag ,LHS % − 0 2 #Cl " AgBr Ag** Br ' * ' K s$ s$(AgBr) %+Ag , +Br , % sp ( $g(r ) '' × 10 −1' * = = '' × 10 −10 M +Ag ,RHS % − 0001 #(r " Cell Cell Reaction E0 Ag → Ag** " '
LHS
*0
$g ) $g +
% -
LHS RHS
Ag* * " ' → Ag
N"/
RHS ''''''''''''''''''''''' ''''''''''''''''''''''' Ag*(RHS) → Ag*(LHS)
K%
*0
$g
+
) $g
0 = −* $g + = −+ ) $g
E0"ll% 0.00
# $g+ "./ # $g+ "-./
E"ll % E
0 "ll
& 005&1 005&1 14 × 10 − log % log ' % 0 − % ' 0.01 n 1 '' × 10 −10
T 345" E"ll $s/!" LHS "ll s67l8 9" 4/68" (*!" 64l: "ll)
2
$ssume $ssume that impure impure copper copper contains contains only iron, iron, silver, silver, and gold as impuritie impurities s $fter passage passage of 140 $, for 4!25 s, the mass of the anode decreased y 2220 g and the cathode increased in mass y 22011 g *stimate the 3 iron and 3 copper originally present
2
he he incr increa ease se in in mass mass of of the the cath cathod ode e is sol solel ely y due due to cop coppe per r .en .ence ce,, ther there e is, is, 220 22011 11 g of of copper e6uivalent to 0'44 mol7 and therefore a total of 024& g of iron, gold and silver 8nly the iron and copper are o+idi9ed he gold and silver fall to the ottom in the anode mud /ince each of the active metals re6uires 2 mol electrons per mol metal, 140 C 1mol e: 1mol M2 + ; 0'500 moles of M2< there must e4!25s7 s &500 C 2 mol he no of moles of iron is therefore 000', and the mass of iron is 020g he metal is 98.88% copper and 0.90% iron.
' =hen a rod rod of metall metallic ic lead lead >as added added to to a 001 M solution solution of of #Coen7 #Coen7 '"'<, it >as found that !3 of the coalt comple+ >as reduced to #Coen7 '" 2< y lead i7 Find Find the the valu value e of of % for for ? < 2#Co 2#Coe en7 n7'"'< ?2< < 2#Coen7 '" 2< ii7 ii7 =hat =hat is the the val value ue of *o #Coen7'"'<@#Coen7 '" 2< GivenA *o ?2<@?7 ; : 012
'
i7
#Coen7'"'< ; 000'2, #Coen7'"2< ; 000! , #?2<" ; 000'4
[? + ][Co( en) + ] 2
2
−1
'
%;
[Co( en) ] '+
−1
'
8n putting the various kno>n values , >e get % ; 0.0154 ii7
;.
0
∆G1
; :nF*°cell ; :2'0' - log % From here >e get, * °cell ; :005' From >hich >e can calculate * #Coen7 ''<)#Coen7 '2<" ; −0.18V
4)
#Fe2+ " #Fe+ "
:r =66 /6" :ll=#g =ll 4/ 4s
"l"/r6"34l "ll> *0
+ Cd ) Cd2
= 0402,
*0
+ Fe2< ) Fe'
= −0BB1
Cd @ Cd2+ 10M7 @@ Fe 2+ , Fe'< ?t7 +lg ? % 0.&,
;.
ˆ† ?C284s7 + Ca2+ + 2e− 4) T6" 64l: "ll r"4/# s ?s7 + CaC28s7 ‡ˆ ˆˆ ˆˆ
9) T6" "ll r"4/# s Cds 7 *cell
0 = *cell −
005& 2
+ 2Fe'+ → Cd2+ + 2Fe2+ +
log
+
#Cd2 "#Fe2 " 2 +
#Fe' "2
/ 4/ 4s "l"/r6"34l "ll *cell
∴*0cell >
005& 2
2+
log
>0
2+ 2
#Cd "#Fe " +
#Fe2 "2
0 H"r" *cell = 0BB1 + 04027 = 11B'
∴11B' >
005& 2
2+ 2
log
0#Fe " +
#Fe' "2
+ #Fe2 " r '&B > log0 + 2log# '+ #Fe " 2+
r log
∴ @.
@.
#Fe " '+
#Fe "
#Fe2+ " '+
#Fe "
< 1&&&log
2+
#Fe " '+
#Fe "
< 20 appro+7
s67l8 9" l"ss /64# 1× 1020
A #87/4#" "ll =4s 4l9r4/"8 9 :ll#g / =/6 4 0.02 M sl7/# : $/4ss73 6lr8" (s$": #87/4#" % 0.2?& / m:1 ) 4#8 3"4s7r#g /6" r"ss/4#" 4/ 2&K =66 =4s :7#8 / 9" ;@. 63s. T6" "ll =4s /6"# :ll"8 =/6 4l73 6lr8" #/4##g 0.@@@g CaCl2 $"r l/r". T6" 3"4s7r"8 r"ss/4#" =4s 10@0 63. C4l7l4/" /6" 3l4r #87/4#" : CaCl2 sl7/#. r KCl sl7/# 1 × cell constant S$": #87/4#" % resistance
02B! ohm:1m−1 =
1 45B'
ohm−1 × cell constant
∴ cell constant ; 02B! × 45B' m:1 % 12?.?
−1
D(1)
m
r CaCl2 sl7/# S$": #87/4#" % C#87/4#" × C"ll #s/4#/ D(2) P7//#g /6" !4l7" : "ll #s/4#/ :r3 "74/# (1) # "74/# (2) ∴ s$": #87/4#" : CaCl2 sl7/#. 1 :1 m−1 % 12 m × 1050
κ = 0120 ohm:1m−1 Q
?.
?.
#. : CaCl2 sl7/# 0555 mole dm:' % 111 % 5 × 10−' mole dm:' % @ 3l" m−' specific conductance Q Molar conductance; concentration 0120 / m2 mol:1 ∧m = 5 % 00241 / m2 mol:1 Ir# s rr8"8 9 4/3s$6"r -g"# 7#8"r 48 #8/# / $r87/ " 2* (4) #s #/4ll. T6" s/4#84r8 r"87/# $/"#/4l 1 − E0"2*F" % −0.;; 4#8 :r /6" r"4/# H 2O ( l ) → 2H* (g) * 82 ( g) + 2e 2 0 E % −1.2 #8 =6"/6"r /6" :r34/# : " 2* (4) s /6"r38#434ll :4!r49l" r #/. T6" r"4/#s 4r" () " (s) () 2H* *
→
1 2
"*2 (4) * 2" '
82 (g) * 2"− →
H2O (l)
0 *Fe ) Fe+2 a67
E0 % *1.2
A88#g "74/# () 4#8 () =" g"/ 1 " (s) * 2H * * 82 (g) → "* (4) * H2O (l) 2 Q
= 044
*0Cell % 1.?
0 ∆G0 = −nF*Cell 0
∴ *Cell % ∴ ∆G
$s/!" % 1.?
0
s #"g4/!". S /6" r"4/# s /6"r38#434ll :4!7r49l" r s$#/4#"7s. .
T6" "3: : /6" "ll r"4/# +2 +2 ns7 + Cua67 → na67 + Cus7 C4l7l4/" /6" "#/r$ 64#g". G!"# /64/ "#/64l$ : /6" r"4/# s − 21?. K 3l −1 0 A#8 *n+2 ) n
.
= −0B 4#8
r /6" "ll r"4/# +2 +2 → na67 ns7 + Cua67
*0Cu+2 ) Cu % * 0.;.
+ Cus7
Q
*0cell
0 = *0ns7 ) n+ + *Cu + 2 a67
2 a67
) Cus7
% 0.? * 0.; % 1.1 0 0 ∴ ∆G % − # *cell % − 2 × ?@00 × 1.1 % − 212. K Q
∆/ = 0
∆.0 − ∆G0
=
−21B − −212'7 2&!
% − 1;.? K −1 3l−1.
&.
A/ 2@C /6" "3: : /6" "ll P9 | P9Cl 2.HCl (0.@ M) || HCl (0.@ M) | AgCl (s) | Ag s 0.; !l/s 4#8 /s /"3$"r4/7r" d* = −1! × 10−4 volt ) degree . C4l7l4/" "::"#/ d 4) /6" "#/r$ 64#g" =6"# 1 g3 3l : sl!"r s 8"$s/"8 4#8 9) /6" 6"4/ : :r34/# : AgCl : /6" 6"4/ : :r34/# : l"48 6lr8" s ' &?000 4l.
&.
T6" #"/ "ll r"4/# 1 1 ? + $gcls7 → $g + ?Cl2 2 2 −1× &500 × 04& ∆G = −nF* = 42 % ' 112?0 4l d∆G7 d* ∆/ = − = nF d d &500 −1! × 10−4 7 % ' ;.1; 4lF8"gr"" % 42 ∆H : /6" r"4/# ∆H % ∆G * T∆S % ' 11200 * 2& × (';.1;) % ' 12;; 4l T6s 6"4/ : r"4/# s /6" 4lg"9r4 s73 : /6" 6"4/s : :r34/# : /6" 3$#"#/s. 1 1 ∆. = . $s + .?Cl2 − .? − .$gCl 2 2 1 1 −124&4 = 0 − × !000 − × 0 − . $gCl 2 2 . $gCl = −4'000 + 124&4 % ' 0@0? 4lF3l"
.
2@ 3L : 4 sl7/# : HCl (0.1M) s 9"#g //r4/"8 $/"#/3"/r4ll 4g4#s/ 0.1 M N4OH sl7/# 7s#g 4 68rg"# "l"/r8" 4s /6" #84/r "l"/r8" 4#8 s4/7r4/"8 4l3"l "l"/r8" (SCE) 4s /6" r":"r"#" "l"/r8". <64/ =7l8 9" /6" EM : /6" "ll #/4ll 4#8 4:/"r /6" 488/# : 20 3L : 4l54l 4/ 2@C> G!"# R"87/# $/"#/4l : SCE % 0.2;22. +lg % 0.@,.
.
T6" g4l!4# "ll :r3"8 # /6s 4s" s 4s :ll=s ?t, .2 1atm7,.+ p. = D7 @@ %Cl satd solution, .g2Cl2s7 , .gl7 , ?t *cell
% */C* redn 7 − *.ydrogen redn 7 % 0.2;22 − 0.0@1 lg + #.+ " % 0.2;22 * 0.0@1 $H 4/ 25°C
Initial pH of the 0.1 HCl: p. = − log#.+ " = − log017 = 1 ∴ *cell % 0.2;22 * 0.0@1 % 0.01 pH after addition of 20 mL alkali: A37#/ : HCl #/4ll $r"s"#/ % 25 × 01 = 25 millimole A37#/ : N4OH 488"8 % 20 × 01 = 2 millimole A37#/ : HCl l":/ 7#r"46"8 % 25 − 2 % 0.@ 3ll3l" 05 05 = 1&5 #.Cl = M ∴ p. = − log 45 45 ∴ *cell = 02422 + 005&1× 1&5 % 0.@;
10.
10.
0 A/ 25°C /6" ∧m !4l7"s :r $g+ 4#8 Cl− #s 4r" 1&2 × 10−4 4#8 B'4 × 10−4 /m2mol −1 r"s$"/!"l 4#8 /6" s$": #87/4#" : 4 s4/7r4/"8 sl7/# : AgCl 4:/"r s79s/r4/#g /6" s$": #87/4#" : =4/"r s 22! × 10−4 /m−1 . C4l7l4/" % sp : AgCl 4/ 25°C .
−4 0 0 ∧m0 $gCl7 = ∧ $g + + ∧ Cl− = 1&2 × B'4710
/m2 mol−1
% 1'!2 × 10−4 /m2mol−1
∧m = % ∴C = ∴ % sp 11.
C %
∧m
≈
%
∧
0 m
=
22! × 10−4 1'!2 × 10
−4
= 15 × 10 −2 mol m−'
% 15 × 10−5 mol dm−' = 15 × 10−5 72 = 2B2 × 10−10 mol2dm
A/ 2@C /6" s$": #87/4#" : 4 s4/7r4/"8 sl7/# : AgCl 4:/"r s79s/r4/#g /6" s$": #87/4#" : =4/"r s 1.&2 × 10 '; S 3 '1. T6" 3l4r #87/4#" 4/ #:#/" 8l7/# : AgNO HNO 4#8 HCl 4r" r"s$"/!"l1.0 ×10 '; ;21.0 ×10 '; 4#8 ;2?.0 ×10 ';S 3 23l '1.
11.
r3 K6lr47s6Js l4= 0
∧m, $gCl
%
∧ m0 , $gE8 + ∧ m0 , .Cl − ∧ m0 , .E8 '
'
';
% (1 * ;2? ' ;21)10 % 1& × 10 '; S 32 3l '1 0
∧m ≈ ∧m
∴ C
% % %
κ
C
κ /m−1 7 ∧0m /m2mol −17 1!2 ×10 −4 '2 ' −4 % 1.2 × 10 3l 3 % 1.32 1'! ×10
10 –5 mol dm –3
C s /6" #"#/r4/# : s4/7r4/"8 sl7/# : AgCl 4#8 6"#" /s sl79l/ K s$ % +Ag*, +Cl ' , % C2 % (1.2 × 10 '@)2 % 1.; × 10 '10 M2 T6" g!"# 64l: "ll s P/ | 0.@ M KCl s4/7r4/"8 =/6 AgCl 4#8 4ls # #/4/ =/6 AgCl (s) T6" 64l:"ll r"4/# r"87/#
AgCl(s) * " Ag(s) * Cl ' C4l7l4/# : E0 AgCl(s) * " Ag(s) * Cl ' (r"87/#) Ag(s) Ag* * " (-84/#) '''''''''''''''''''''''''''''''' AgCl(s) Ag* * Cl ' ("ll r"4/# =66 s sl79l/ "7l9r73 #/rll"8 9 K s$) 0 0 0 * cell % * reduction (RHE =6"r" r"87/# 7r) ' *reduction (LHE =6"r" -84/# 7rs) 0 % * $gCl, $g, Cl
−
0.0@ lg K s$ %
0 * $g
−
+
0 * $gCl , $g, Cl
−
, $g −
0 !0
0 * $gCl , $g, Cl % 0.224 −
12.
C4l7l4/" /6" "7l9r73 #s/4#/ :r /6" r"4/# 2Fe'+
ˆ† + '− ‡ˆ ˆˆ ˆˆ
2Fe2 +
+ '− . T6" s/4#84r8
r"87/# $/"#/4ls # 48 #8/#s 4r" 0. 4#8 0.@; r"s$"/!"l :r Fe'+ ) Fe2+ 4#8 −
−
' ) 7$l"s. (4#/lg .?? % 2 × 10B ).
12.
r /6" 6"34l 64#g" ˆ† 2Fe2+ + '− 2Fe'+ + '− ‡ˆ ˆˆ ˆˆ A/ "7l9r73 *cell = 0 005& 005& 0 log% c ⇒ *0cell = log% c As *cell = *cell − 2 2 0 0 *0cell = *-? −* = 0BB − 054 = 02' − − '+ 2+ Fe
T67s 02' = log% c
=
-?' ) 7
)Fe
005&
2 2 × 02' 05&
log% c
= BB&
∴%c = 2 × 10B 1.
Sl7/#
0.@ N sl7/# : 4 s4l/ $l4"8 9"/=""# /= $l4/#73 "l"/r8" 2.0 3 4$4r/ 4#8 : 4r"4 : rsss"/# ;.0 s. 3 64s 4 r"ss/4#" : 2@ 63s. C4l7l4/" /6" "7!4l"#/ #87/4#" : sl7/#. S$": #87/4#" (κ ) % C#87/4#" × C"ll #s/4#/ %
l 1 2 × × ÷ % 0.02 63 '1 3 '1 % ÷ 25 4 - a 1
∧ %
1;.
1;.
specific
conduc t an ce C e6uiv
×1000
−1
7
%
02 × 1000 05
% ;0 63 '1 32 " '1
#8 /6" sl79l/ $r87/ : 4 s4/7r4/"8 sl7/# : Ag 2CrO; # =4/"r 4/ 2&K : /6" "3: : /6" "ll Ag | Ag * (s4/ Ag2CrO; sl7/#) || Ag * (0.1 M) | Ag s 0.1?; 4/ 2&K r "ll Ag | Ag* (s4/7r4/"8 sl7/# : Ag 2CrO;) || Ag* (0.1 M) | Ag E"ll % 0.1?; 005&
E"ll % E0"ll '
1
log
#$g+ "./ +
#$g "-./
⇒ 0.1?;
% * $g) $g+ + * $g+ ) 4 − 0
0
*
005& 1
log
#$g+ "./ 01
';
∴ +Ag
,LHS % 1.?? × 10 M K s$ :r Ag2CrO; 2Ag* * CrO;2' * 2
K s$ % +Ag , +CrO ∴ K s$ %
1 × 10−4 , % +1.?? × 10 , 2
2' ;
'; 2
2.2& × 10 '12 3l ll/r" '
1@.
A #s/4#/ 7rr"#/ =4s :l=# :r 2 67r /6r7g6 4 sl7/# : KI. A/ /6" "#8 : "-$"r3"#/ l9"r4/"8 8#" #s73"8 21.@ 3L : 0.0&1 M sl7/# : s873 /6s7l$64/" :ll=#g /6" r"4/# I2 * 2S2O2' → 2I ' * S;O?2' . <64/ =4s /6" 4!"r4g" r4/" : 7rr"#/ :l= # 43$"r">
15A
2S2O2' → S;O?2' * 2" #:4/r : s873 /6s7l$64/" % #. : "l"/r#s ls/ $"r 3l"7l" % 1 ∴ Ml4r/ : N4 2S2O sl7/# % Nr34l/ 3". : I 2 l9"r4/"8 % 3 "7!. : N4 2S2O % 21.@ × 0.0&1 % 1.&0 T67s = × 1000 % 1.&0 * = ' *
% 1.& × 10 %
∴
i ×t &500
=
i × 2 × 0 × 0 &500
% 0.02;2A
1@.
T6" 64l: "ll $/"#/4l : 4 64l: "ll A-* A(-*#)*FP/ ="r" :7#8 / 9" 4s :ll=s P"r"#/ : r"87"8 :r3 2;.; ;&.& C"ll $/"#/4l F 0.101 0.11@ "/"r3#" /6" !4l7" : #
1@.
T6" 64l: "ll r"4/# s A(-*#)* * #" ' → A-* I/s N"r#s/ "74/# 005&
E % E '
n
log
#reduced form" #o+idised form"
S79s//7/#g /6" g!"# !4l7"s =" g"/ 244 005& lg () B5 n
0.101 % E '
005&
0.11@ % E '
n
log
4!! 512
()
S79s/r4/#g "74/# () :r3 () 4#8 sl!#g :r # n 1.!" 2 1?.
1?.
T= ="45 48 sl7/#s . $ 4#8 . $ "46 =/6 s43" #"#/r4/# 4#8 64!#g $K4 !4l7"s 4#8 @ 4r" $l4"8 # #/4/ =/6 68rg"#"l"/r8" (1 4/3 2@) 4#8 4r" #/"r##"/"8 /6r7g6 4 s4l/9r8g". #8 ".3.:. : "ll. T6" "ll s r"$r"s"#/"8 4s P/ H2(1 4/3) | HA2 || HA1 | H2 (1 4/3) P/ 1
A/ L.H.S. *.) .+
=
0 % *. ).+ + 005&2 p.72
0 *.) .+
−
2
005&2 log#.+ "2 1
A/ R.H.S. *.
.
= *.0 + ) . −
).
005&2 1
log
1 +
#. "1
0 % *.+ ). − 005&2p.71
−
r 48 . $ . $ 1
H* * $1
1
+H*, % % a × c
∴ ($H)1 %
1
S3l4rl ($H)2 %
2
p%a2
−
1 1 p%a1 − lg 2 2
1 2
C
logc
+S#" #"#/r4/# : 9/6 48s HA 1 4#8 HA2 4r" s43" .". , ∴ E"ll % *.) .+ for 7 + *.+ ) . 0
%
0
005&2
7 % 0.0@2 ×
1 2
p%a − p%a 2
1
E"ll % 0.05!2
#5 − '"
2
for
1B
he standard reduction potential for the half:cell − E8' a67 < 2.<a67 < e → E82g7 < .28 is 0B! volt i7 Calculate the reduction potential in ! M .< ii7 =hat >ill e the reduction potential of the half cell in a neutral solutionD $ssume all other species to e at unit concentration
1B
he half cell is E8'− a67 ; 2.< a67 < e → E82g7 < .2;8 Given
0 *E8 − ) E8 '
∴ *E8'− ) E82
; 0B! ; 0B!
2
1
005&2
log #.+ "2
1
1 0 005&2 = *E8 − log #.+ "2 )E8 : 1 '
2
005&2
log
1 005&2 1
1 !72 −1
log47
; 0B! < 005&2 log 4 ; 0B! < 005&2 log2 ; 0!!&& volt n neutral solution #.<" ; 10 B M 0
∴ *el ; *el
;
*0el
−
005&2
; 0B!
1
005&2 1 log
1
log #.+ "2
1 −B
2
10 7
; 0B!
005&2 1
14
log10
005&2 14 × log10 ; 0B! 0!2!! 1
; – 0.0488 volt 1!
Calculate the potential of an indicator electrode versus the standard hydrogen electrode >hich originally 01M Mn84 and 0!M . < and >hich has een treated >ith &03 of the Fe 2< necessary to reduce all the Mn84 to Mn2< Mn84 < !.< < 5e → Mn2< < 4.28 *H ; 151
1!
et us consider Galvanic cell is .< 1M7 @ .21atm7, ?t @@ Mn84 .<7 @ Mn<2, ?t $node half cell A 2.< 1M7 → .2 1atm7 < 2e Cathode half cellA Mn84 < !.< < 5e → Mn<2 < 4.28
nitial ConcA
01 01 $lter Complete 01 ÷ 100
0! 0! − 01× &0 × ! ÷ 100
0
0 01× &0 100
reaction >ith Fe<2 0017 00!7 /o, electrode potential of indicator electrode *Mn8− ) Mn+2
o ; * Mn8− ) Mn+
2
4
4
−
005&1 5
00&7 +
log
#Mn2 " #Mn8:4 " #.+ "!
; 151
005&1 00&7 log 5 0017 00!7!
; 151
005&1 & log 5 1B × 10−&
; 151
005&1 log 5' × 10&7 5
; 151 0114& ; 1.395 V hus, potential of an indicator electrode versus the /.* is 1'&5 ecause * /.* ; 0
1.
T6" ".3.: : "ll #s|#SO;|| C7SO;|C7s 4/ 2@°C s 0.0 4#8 /"3$"r4/7r" "::"#/ : ".3.: s ('1.;×10; ) $"r 8"gr"". C4l7l4/" /6" 6"4/ : r"4/# :r /6" 64#g" /45#g $l4"
1.
#s8" /6" "ll. % ?@00 C E % 0.0 T % 2*2@ % 2& K #%2
d* % 1.;×10; $"r 8"gr"" d ? d* − * As ∆H % # d ? % 2×?@00 +2& ×(1.;×10;)0.0, % 1&;2 F3l % '1.&;2 KF3l 20.
20.
A /"s/ :r 3$l"/" r"3!4l : C7 2* #s :r3 4 sl7/# : C7 2*(4) s / 488 NH (4). A 9l7" l7r sg#:"s /6" :r34/# : 3$l"- +C7(NH );,2* 64!#g K : % 1.1 × 101 4#8 /67s #:r3s /6" $r"s"#" : C72* # sl7/#. 2@0 3l : 0.1M C7SO ;(4) s "l"/rl"8 9 $4ss#g 4 7rr"#/ : .@ 43$"r" :r 1@0 s"#8s. T6"# s7::"#/ 74#// : NH (4) s 488"8 / /6" "l"/rl"8 sl7/# 34#/4##g +NH , % 0.1 M. I: +C7(NH);,2* s 8"/"/49l" 7$/ /s #"#/r4/# 4s l= 4s 1 × 10 '@ =7l8 4 9l7" l7r 9" s6=# 9 /6" "l"/rl"8 sl7/# # 488/# : NH > C72* * ;NH +C7(NH);,2* #CuE.' 74 "2+ K : % #Cu2+ "#E.' "4 Bl7" l7r =ll 9" #/"8 7$/ +C7(NH );,2*% 1 × 10 '@ T67s 4/ /6s s/4g" 2*
+C7 , %
10 ×10 −5 11×10
1'
C7 8"$s/"8 (=) %
× 017
4
*it &500
% .1 × 10 '1@M %
'5 × '5 ×1'50 2 × &500
% 1.@@;? g3s
Mll3l"s : C72* $r"s"#/ (#/4l) % 2@0 × 0.1 250 × 01× '5
<"g6/ : C72* %
% 1.@&@ g3s
1000
<"g6/ : C72* l":/ # sl7/# % 1.@&@ ' 1.@@;? % 0.02 g3s +C72*, l":/ %
00'2& × 1000 '5 × 250
% 2.0 × 10 '
T67s sl7/# =ll s6= 9l7" l7r 4s / =ll $r!8" 4$$r"49l" C7 2* / :r3 3$l"-. 21.
A s43$l" : l"48 ="g6#g 1.0@ g =4s 8ssl!"8 # 4 s34ll 74#// : #/r 48 / $r87" 47"7s sl7/# : P9 2* 4#8 Ag* (=66 s $r"s"#/ 4s 3$7r/). T6" !l73" : /6" sl7/# =4s #r"4s"8 / 00 3l 9 488#g =4/"r 4 $7r" sl!"r "l"/r8" =4s 33"rs"8 # /6" sl7/# 4#8 /6" $/"#/4l 8::"r"#" 9"/=""# /6s "l"/r8" 4#8 4 s/4#84r8 68rg"# "l"/r8" o =4s :7#8 / 9" 0.@0 4/ 2@C. <64/ =4s /6" : Ag # /6" l"48 3"/4l> G!"# * $g ) $g 7 %0. . N"gl"/ 437#/ : Ag * #!"r/"8 / Ag. +
1
005&
21.
E % E '
1
lg # $g " +
005&
0.@0 % 0. '
1
log
1 +
# $g "
+Ag*, % .?2 × 10 '? M '00
Ml"s : Ag* % .?2 × 10 '? × 1000 % 2.& × 10 '? M4ss : Ag % 2.& × 10 '? × 10& % .11 × 10 '; g ∴ P"r"#/4g" : Ag % 0.02? 22.
T6" EM : /6" "ll P/ |H 2 (1 4/3) HA (0.1 M 0 3l) || Ag * (0.& M) | Ag s 0.. C4l7l4/" /6" EM =6"# 0.0@ M N4OH (;0 3l) s 488"8 / /6" 4/68" 3$4r/3"#/. HA s 4 ="45 48. 0 + * $g+ ) $g = 0BB lg ?.%0.& lg 2%0.01,
005& 22.
S#" E % E0C ' E0A ' 0. % 0. ' 0 ' ∴ K 4 %
005& 1
1 log
log
.+
[ +] [? ] $g 1) 2
.2
%a ×c 1×0!
';
2.@ × 10 <6"# ;0 3l 4#8 N4OH s 488"8 /6" +H *, s g!"# 9
( 005 × 40
$H % $K 4 * lg ( 01× '0 − 005 × 40 ) $H % ; ' lg 2.@ * 0.0120 % . +H*, % 1.2@ × 10 '; 005& 125 × 10 −4 log E % 0. 1 1× 0! % 0.; 2. 2.
S$": #87/4#" : 4 8"#r34l sl7/# : KCl s 0.022; ohm−1cm−1 . T6" r"ss/4#" : 4 "ll #/4##g /6" sl7/# =4s :7#8 / 9" ?;. <64/ s /6" "ll #s/4#/> <" 5#=# /64/ s$. #87/4#" % "ll #s/4#/ × #87/4#" sp conduc tance C"ll #s/4#/ % conduc tance % s$ #87/4#" × r"ss/4#" % 0.022; ×?; % 1.;? 3 1
2;.
2;.
2@.
2@.
C4l7l4/" /6" "l"/r8" $/"#/4l : 4 $$"r "l"/r8" 8$$"8 # 4 0.1 M sl7/# : $$"r +2 s7l$64/" 4/ 250 C /6" s/4#84r8 "l"/r8" $/"#/4l : Cu @ Cu ss/"3 s 0.; !l/s 4/ 2& K. 005&1 o = + * * log10 ion7 red red <" 5#=# /64/ n o P7//#g /6" !4l7"s : *red % 0.; # % 2 4#8 +C7 2*, % 0.1 M 005&1 log017 Er"8 %0.& * 2 % 0. ;*0.02@@ ×(1) % 0.; ' 0.02@@ % 0.10;@ !l/ +2 + T6" s/4#84r8 r"87/# $/"#/4l : Cu @ Cu and $g @ $g "l"/r8"s 4r" 0.; 4#8 0.&0 !l/ r"s$"/!"l. C#s/r7/ 4 g4l!4# "ll 7s#g /6"s" "l"/r8"s s /64/ /s s/4#84r8 "3: s + $s/!". r =64/ #"#/r4/# : $g =ll /6" "3: : /6" "ll 4/ 250 C 9" "r. I: #"#/r4/# : Cu+2 s 0.02 M> ° ° G!"# *Cu+2 ) Cu = 0'4 !l/ 4#8 * $g+ ) $g = 0!0 !l/ /6" s/4#84r8 "3: =ll 9" $s/!" :
C7FC72* s 4#8" 4#8 Ag *FAg s 4/68". T6" "ll 4# 9" r"$r"s"#/"8 4s C7FC7 *2||Ag*|Ag T6" "ll r"4/# s C7*2Ag* → C72* * 2Ag *° % - $/"#/4l : 4#8" * r"8 $/"#/4l : 4/68" cell
% 0.; * 0.&0 % 0.;? !l/ 4$$l#g #"-/ "74/# *Cell
= *°cell −
005&1 2
Cu+2 log 2 $g+
<6"# E"ll % 0 *°cell
=
005&1 2
Cu+2 log 2 $g+
Cu+2 = 2 × 042 = 15'45 lg 2 005&1 $g+ Cu2+ = 4'102 × 1015 2 $g+ 2
002 $g+ = 0440 × 10 −1B = 4'102 × 1015
+Ag*, % 2.1@; ×10 M
