Variation of Conductance with Temperature in Electrolytes
CERTIFICATE This is to certify that Deen Dayal student of Class XII A, Mother Divine Public School has completed the project titled Variation of Conductance with Temperature in Electrolytes during the academic
year 2008-2009 toards partial fulfillment of credit for the Chemistry practical e!aluation of AI""C# 2009, and su$mitted satisfactory report, as compiled in the folloing pages, under my super!ision% Mrs Janet Garrison
&epartment of Chemistry 'other &i!ine (u$lic "chool
Acknowledgements
“There are times when silence speaks so much more loudly than words of praise to only as good as belittle a person, whose words do not epress, but only put a !eneer o!er true feelings, which are of gratitude at this point of time"# I would like to epress my sincere gratitude to my chemistry mentor Mrs Janet Garrison, for her !ital support, guidance and encouragement $ without which this pro%ect would not ha!e come forth" I would also like to epress my gratitude to the sta& of the 'epartment of Chemistry at (outh )ark Elementary for their support during the making of this pro%ect"
Inde )% Certificate***************************%% + 2% Acnoledgements***********************% +% Aim******************************* . % Apparatus**************************** / .% Important Terms************************%% /% Conducti!ity**************************%% 8 % 1actors Affecting #lectrical Conducti!ity************%% 9 8% (rocedure***************************%% )0 9% (hysical Constants*********************** )) )0%
$ser!ation "et )*********************%% )2
))% 3raph of $ser!ation "et)****************% )+ )2%
$ser!ation "et2*********************%% )
)+%
3raph of $ser!ation "et2****************% ).
)%4esult***************************** )/ ).%Conclusion**************************%% ) )/%(recautions**************************% )8
)%5i$liography************************** )9
I6T4&7CTI6
AI' To find the !ariation of conductance ith temperature in electrolytes
A((A4AT7" 3lass $eaer, Cu" solution, Cu electrodes, n" solution, n electrodes, rheostat, $attery eliminator, ater, $urner, thermometer, flas, ammeter, !oltmeter
T#4: ;
Conductance The property of ease of flo of electric current
through a $ody is called conductance% ;
!esistance The o$stacle offered to the flo of electric current is
called resistance% ;
Electrolysis The operation in hich electricity causes a chemical
reaction is called electrolysis% ;
"hm#s $aw This la states that the current floing through a
resistance is directly proportional to the potential difference applied across it
V=IxR % &araday#s $aws
o 1irst =a> The mass of a su$stance produced or consumed in electrolysis is directly proportional to the ?uantity of charge passing through it% m
(X
Q
or, m = @ I @ t
here, is electrochemical e?ui!alent I is current t is time in seconds Q is charge% o "econd
=a>
The mass of su$stance
produced
in electrolysis
directly proportional to its e?ui!alent mass% !" # E" = !$ # E$ = !% # E%& o Third =a> The mass of a su$stance produced in electrolysis is
directly proportional to the num$er of electrons per mole needed to cause desired change in o@idation state% Conducti!ity Bhen !oltage is applied to the electrodes immersed into an electrolyte solution, ions of electrolyte mo!e, and thus, electric current flos through the electrolytic solution% The electrolytic solution and the metal conductors e@hi$it resistance to the passage of the current $oth of hich o$ey hm
The reciprocal of resistance is called electrical conductance% The unit of electrical conductance is 'iemens (' or ohm-) or mho% If a solution is placed $eteen to parallel electrodes ha!ing cross sectional area ) and distance * apart then the resistance is gi!en $y R = " # C p called Drho
conducti!ity of the solution, hich is denoted $y + called +appa-. Its unit is 'iemens#meter. /="#R0*#) *# ) is a fi@ed ?uantity for a cell and is called the Dcell constant<%
1actors Affecting #lectrical Conducti!ity The factors hich affect the electrical conducti!ity of the solutions are> ;
'nter(ionic attraction It depends on solute- solute interactions%
;
Solvation of ions It depends on solute-sol!ent interactions%
;
Viscosity of the solvent It depends on sol!ent-sol!ent
interactions% (hysical Constants 1or the purpose of accuracy and con!enience, some important aspects of the electrolyte process are ept constant in the e@periment as their !ariation might affect the conducti!ity of the electrolyte% They are>
;
Foltage
;
6ature of electrodes
;
"iGe of electrodes
;
"eparation $eteen the electrodes
;
Concentration of the electrolytes
;
6ature of the electrolytes
;
4esistance in the circuit
(4C#&74# )% The electrolyte chosen is n" and the electrodes are of n% 2% 4eadings for the measurement of conductance are taen at inter!als of + &C% +% (roper precautions are taen to a!oid e!aporation and to eep other factors constant% % The !essel and electrodes are remo!ed and the !essel is cleaned and filled ith n" solution% .% The electrodes are refitted in their original place so that the distance $eteen them does not change%
/% Current is passed and hen the !oltmeter and ammeter sho steady readings, they are noted% % The current is sitched off% )% It is seen that hile the ammeter reading returns at once to 0 position% The !oltmeter needle pauses for a hile at a particular reading hich is noted don% 2% This reading indicates the $ac #'1 in the electrolyte% )% "imilarly, more sets of reading are taen, and resistance is calculated% 2% Thus, the !alue of conductance is calculated% )% The sitched on circuit readings in !oltmeter and ammeter are taen% 2% The current through the electrolyte is changed $y adjusting the rheostat and more sets of readings are taen% +% Thus, the mean !alue of resistance is calculated% )% A$o!e steps are repeated for Cu" as electrolyte ith electrodes made of Cu%
5"#4FATI6 "#T ) 1or n'23 electrolyte with n electrodes
"
Temperatur e
6 o
4eading of
4eading of
4esistanc e
Conductanc e
Ammete r
Foltmete r
I
V
R = V #"
C="#R
)
2+
)00 mA
)%0 F
)0 H
0%)00 H -)
2
2/
)00 mA
0%9. F
9%. H
0%)0. H -)
+
29
))0 mA
0%89 F
8%09 H
0%)20 H -)
+2
))0 mA
0%8 F
%/+ H
0%)+0 H -)
.
+.
)20 mA
0%80 F
/%// H
0%).0 H -)
/
+8
)2. mA
0%. F
/%00 H
0%)/0 H -)
)
)+0 mA
0%) F
%/ H
0%)80 H -)
8
)+0 mA
0%/. F
.%00 H
0%200 H -)
3raph of $ser!ation "et ) inc "ulphate #lectrolyte 0%) 0%0.
Temperature in degree CelsiusE
5"#4FATI6 "#T 2 1or Cu'23 electrolyte
" 6o
Temper -ature
4eading of Foltmeter
4esistance
Conductanc e
I
V
R = V #"
C = "#R
4eading of Ammeter
)
2.C
. mA
)% F
)8%/ H
0%0.+ H -)
2
28C
. mA
)%+. F
)8%00 H
0%0.. H -)
+
+)C
. mA
)%+ F
)%++ H
0%0. H -)
+C
. mA
)%2. F
)/%/ H
0%0/0 H -)
.
+/C
80 mA
)%2 F
).%00 H
0%0// H -)
/
+8C
80 mA
)%). F
)%+8 H
0%0/9 H -)
2C
80 mA
)%)0 F
)+%. H
0%02 H -)
8
C
8. mA
)%)0 F
)2%9 H
0%0. H -)
9
C
8. mA
)%0. F
)2%+. H
0%080 H -)
)0
9C
90 mA
)%)0 F
))%)) H
0%090 H -)
))
.2C
90 mA
)%90 F
)0%00 H
0%)00 H -)
3raph of $ser!ation "et 2 0%0/ o )c
"
0%0 T" "
0%02 o"
4#"7=T The rele!ant graph shos that the " # Resistance of an electrolyte increases at a steady rate as the temperature increases%
C6C=7"I6 n heating a solution, it is non that !iscosity gradually decreases, ith decrease in !iscosity, the speed and mo!ement of the ions increases% In other ords, the conductance of the electrolyte increases ith increases in temperature% ence, the result of the e@periment agrees ith reasoning% (recautions ;
Fariation of resistance due to one of the factors should $e ept
constant% ;
The electrodes used in each case should alays $e ept parallel to
each other%
;
The solution should $e ept undistur$ed throughout the
e@periment% ;
1or each o$ser!ation, three readings are taen and the mean
!alue is considered%
5I5=I34A(: ;
Chemistry (4art I 5 Text6oo+ for Class XII7 6ational Council of
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