EXPERIMENT 3: ACID AND BASE TITRATION
TITLE:
Acid and Base Titration
OBJECTIVES:
To determ determine ine the concen concentrat tration ion of sodium sodium hydro hydroxid xidee soluti solution on throug through h titrati titration on technique using hydrochloric acid and sulfuric acid.
CONCEPTS: •
To determ determine ine the concen concentrat tration ionss of acid and base base soluti solution on throug through h titrati titration on with with standard solution.
•
To apply the correct technique in titration.
•
To carry out acid base titration using phenolphthalein as indicator.
INTRODUCTION:
Acid base titration involves a neutralization reaction in which an acid is react wih an equivalent amount of base. For the neutralization of hydrochloric acid with sodium hydroxide:
!l " #a$
%$ " #a!l
#eutralization occurs when acid and base exists in comparable stoichiometry& for instance the amount of hydrochloric acid 'mole( is equivalent with the amount of sodium hydroxide 'mole(. The end point of titration c an be determined using indicator.
MATERIALS:
a( )** ml *.) + !l solution b( )** ml *.) + %,$%,$- solution c( )* ml C solution containing #a$ 'with pipette( d( henolphalein solution
METHODS:
). )* ml of ! solution was put into volumetric flas/& was diluted with distilled water to the mar/ and was mar/ troughly. The solution was transferred to a clean bea/er and was labeled as !. Then a flas/ was rinsed with water twice. %. The burette was clean and was rinsed with 0 +l !l solution '*.) +( twice. Then 0* ml of !l solution '*.)+( to burette using funnel. 1. The pipette was clean and was rinsed twice using ! solution. %0 +l of ! solution in three 2rlenmeyer flas/. % drops of phenolphthalein was added as indicator. -. The initial volume reading was recorded to the nearest two decimal points. The ! solution was titrated with !l from burette to a colourless solution end point. The final volume reading was recorded and was calculated the used of acid volume. 0. The titration was repeated until the different volume of acid is in the range of *.1* for three experiments. 3. The concentration of #a$ solution 'that was in flas/( the concentrations of ! was calculated. 4. The steps 1 to 4 was repeated by replace !l with %,$-.
RESULTS:
)( Titration #a$ with !l HCl + NaOH
H2O + NaCl
Reading 5olume of !l ' initial (
Tial ! **.**
Tial 2 **.**
Tial 3 **.**
m6 5olume of !l ' final (
-3.0*
-3.7*
-0.**
m6 5olume
-3.0*
-3.7*
-0.**
' m6(
of
!l
used
T"e e#$a%i&n i': NaOH (a#) + HCl (a#)
NaCl (a#)
+ H2* (l)
CALCULATIONS :
calculation for !l : ) mol of !l react with ) mol of #a$ !oncentration of #a$ :
TRIAL ! :
+ol !l react with #a$ : +ole 8 +5 )*** 8 '*.)('-3.0*(
)***
+ole of !l react 8 -.30 9 )* 1 mol of !l. +ole of #a$ present 'in 2rlenmeyer flas/( From the equation& ) mole of !l react with ) mole of #a$& ,o& ) mole of !l 8 ) mole of #a$ ,o that& mole of #a$ present 8 -.30 9 )* - mol
M&lai% &, NaOH- .NaOH/ ! :
+olarity 8
mole of solute
.
5olume of solution '6( 8 -.30 9 )*1 mol *.*0* 6 8 7.1* 9 )*% +
TRIAL 2 :
+ol !l react with #a$ : +ole 8 +5 )*** 8 '*.)('-3.7*(
)***
+ole of !l react 8 -.37 9 )* 1 mol of !l.
+ole of #a$ present 'in 2rlenmeyer flas/( From the equation& ) mole of !l react with ) mole of #a$& ,o& ) mole of !l 8 ) mole of #a$ ,o that& mole of #a$ present 8 -.37 9 )* 1 mol
M&lai% &, NaOH- .NaOH/ 2 :
+olarity 8
mole of solute
.
5olume of solution '6( 8 -.37 9 )*1 mol *.*0* 6 8 7.1; 9 )*% +
TRIAL 3 :
+ol !l react with #a$ : +ole 8 +5 )*** 8 '*.)('-0.**(
)***
+ole of !l react 8 -.0* 9 )* 1 mol of !l. +ole of #a$ present 'in 2rlenmeyer flas/( From the equation& ) mole of !l react with ) mole of #a$& ,o& ) mole of !l 8 ) mole of #a$ ,o that& mole of #a$ present 8 -.0* 9 )* 1 mol
M&lai% &, NaOH- .NaOH/ 2 :
+olarity 8
mole of solute
.
5olume of solution '6( 8 -.0* 9 )*1 mol *.*0* 6 8 7.**9 )*% +
Average molarity 8 7.1* 9 )*% + " 7.1; 9 )* % + " 7.** 9 ).* % + 1 8 7.%1 9 )*% +
S%andad de0ia%i&n .NaOH/ 1 .NaOH/ .NaOH/ a0 !**4
.NaOH/a0
TRIAL ! :
,tandard deviation 8
7.1* 9 )* % + '7.%1 9 )* % +( x )**< '7.%1 9 )*% +(
1
*.43 <
TRIAL 2 :
,tandard deviation 8
7.1; 9 )* % + '7.%1 9 )*% +( x )**< '7.%1 9 )* % +(
1
).31<
TRIAL 3 :
,tandard deviation 8 7.** 9 )* % + '7.%1 9 )* % +( x )**< '7.%1 9 )* % +( 1 %.-7<
The accepted value of concentration of #a$ is 7.1* 9 )* % + because the standard deviation is the smallest value. The concentration of #a$ solution'that was in flas/( and the concentration of ! is calculated as: +)5)8+%5% '+)( '*.*)6(8' 7.1* x )* % +( '*.*0*6( +) 8 *.-3%+
Ti%a%i&n NaOH 5i%" H2SO6
Reading 5olume of %,$- ' initial (
Tial ! **.**
Tial 2 **.**
Tial 3 **.**
m6 5olume of %,$- ' final ( m6
%1.4*
%-.%*
%1.1*
5olume of %,$- used
%1.4*
%-.%*
%1.1*
' m
6(
T"e e#$a%i&n i': 2 NaOH + H2SO6
Na2SO6 + 2 H2*
'%( calculation for %,$- : % mol of #a$ react with ) mol of %,$!oncentration of #a$ :
TRIAL ! :
+ol !l react with #a$ : +ole 8 +5 )*** 8 '*.)('%1.4*(
)***
+ole of %,$- react 8 %.14 9 )* 1 mol of %,$+ole of #a$ present 'in 2rlenmeyer flas/( From the equation& ) mole of %,$- react with % mole of #a$& ,o& ) mole of !l 8 % mole of #a$ ,o that& mole of #a$ present 8 -.4- 9 )* 1 mol
M&lai% &, NaOH- .NaOH/ ! :
+olarity 8
mole of solute
.
5olume of solution '6(
8 -.4- 9 )*1 mol *.*0* 6
8 7.-;9 )*% +
TRIAL 2 :
+ol %,$- react with #a$ : +ole 8 +5 )***
8 '*.)('%-.%*(
)***
+ole of %,$- react 8 %.-% 9 )* 1 mol of %,$-. +ole of #a$ present 'in 2rlenmeyer flas/( From the equation& ) mole of %,$- react with % mole of #a$& ,o& ) mole of %,$- 8 % mole of #a$ ,o that& mole of #a$ present 8 -.;- 9 )* 1 mol
M&lai% &, NaOH- .NaOH/ 2 :
+olarity 8
mole of solute
.
5olume of solution '6(
8 -.;-9 )*1 mol *.*0* 6
8 7.3; 9 )* % +
TRIAL 3 :
+ol !l react with #a$ : +ole 8 +5 )*** 8 '*.)('%1.1*(
)***
+ole of %,$- react 8 %.11 9 )* 1 mol of %,$+ole of #a$ present 'in 2rlenmeyer flas/( From the equation& ) mole of %,$- react with % mole of #a$& ,o& ) mole of !l 8 % mole of #a$ ,o that& mole of #a$ present 8 -.33 9 )* 1 mol
M&lai% &, NaOH- .NaOH/ ! :
+olarity 8
mole of solute
.
5olume of solution '6( 8 -.33 9 )*1 mol *.*0* 6
8 7.1% 9 )*% +
Average molarity 8 7.-;9 )* %+ " 7.3; 9 )* % + " 7.1% 9 )* % +
1 8 7.-7 x )*% +
S%andad de0ia%i&n .NaOH/ 1 .NaOH/ .NaOH/ a0 !**4
.NaOH/a0
TRIAL ! :
,tandard deviation 8
7.-; 9 )* % + '7.-7 9 )*% +( x )**< '7.-7 9 )* % +(
1 7*.))<
TRIAL 2 :
,tandard deviation 8
7.3; 9 )* % + '7.-7 9 )*% +( x )**< '7.-7 9 )* % +(
1 %.**<
TRIAL 3 :
,tandard deviation 8
7.1% 9 )* % + '7.-7 9 )*% +( x )**< '7.-7 9 )* % +(
1 ).47<
From the calculation of the standard deviation above&there are no accepted value for concentration #a$ because of no smallest standard deviation which is approaching zero. 7.-;9 )* %+. But the nearest value to the average value is The concentration of #a$ solution'that was in flas/( and the concentration of ! is calculated as: +)5)8+%5% '+)( '*.*)6(8' 7.-;x )* % +( '*.*0*6( +) 8 *.-4-+
DISCUSSION:
Ti%a%i&n 'e%$89 T"e $e%%e 5&$ld n&;all e "eld a
To determine the concentration of a particular solute in a solution& chemists often carry out a titration& which involves combining a sample of the solution with a reagent solution of /nown concentration& called standard solution. A titration is a procedure in which a solution of /nown concentration is reacted with /nown volume of a solution of un/nown concentration in order to measure the latter=s concentration. Titrations can be conducted using acidbase& precipitation& or oxidation reactions. $ne of the reactants is the titrate which is added to other one& the analyte is an un/nown. An acidbase titration is a method in chemistry that allows quantitative analysis of the concentration of an un/nown acid or base solution. >t ma/es use of the neutralization reaction that occurs between acids and bases& and that we /now how acids and bases will react if we /now their formula. From our experiment& we want to determine the concentration of sodium hydroxide solution through titration technique using hydrochloric acid and sulfuric acid. For the first experiment is the neutralization of hydrochloric acid with sodium hydroxide& the equation is :
HCl + NaOH
H2O + NaCl
>n the titration by using !l as the acid solution and #a$ as the base solution& the concentration of solution ! containing #a$ solution that we got is 7.1* 9 )* % +. This molarity was accepted because the standard deviation shows the value zero and also near to the average value. The concentration of #a$ solution 'that was in flas/( and the
concentration of ! is calculated and the result is *.-3% +. For the second experiment is the neutralization of sulfuric acid with sodium hydroxide& the equation of the reaction is: 2 NaOH + H2SO6
Na2SO6 + 2 H2
Besides that& in the titration by using !l as the acid solution and #a$ as the base solution& the concentration of solution ! containing #a$ solution that we got is 7.-;x )*% +. This value is zero and near to average value. The concentration of #a$ solution 'that was in the flas/ ( and the concentration of ! using sulfuric acid we got is *.-4- +. The concentration of solution ! containing #a$ should be the same either by using !l or %,$- as the acid solution& but in this experiment& we got the value of concentration #a$ through the experiment by using !l& *.-3% + and concentration of #a$ by using %,$- is *.-4-+ . To titrate an un/nown with standard solution& there must be some way to determine when equivalence point of the titration has been reached. >n acidbase titrations& dyes as acid base indicators are used for this purpose. The indicator that use in this experiment is phenolphthalein is colorless in acidic solution but is pin/ in basic solution. >f we add phenolphthalein to an un/nown solution of acids& the solution will be colorless. ?e can then add standard base from buret until the solution barely turns from colorless to pin/. This color change indicates that the cid has been neutralized and drop of base that caused the solution to become colored has no acid react with. The solution therefore becomes basic& and the dye turns pin/. The color change signals the end point of the titration.& which usually coincides very nearly with the equivalence point. !are must be ta/en choose indicators whose end points correspond to the equivalence point of the titration. ,ome precaution during do this experiment. First& each apparatus must be rinse with the solution that will fill into their apparatus. Besides that& we must measure the volume of the solution properly especially during ma/e dilution solution. ?e must sha/e the sha/e the solution in 2rlenmeyer flas/ during titration process. +a/e sure the solution from the burrete flow very slowly to avoid some mista/e during ta/e the reading.
CONCLUSION:
For the conclusion& in this experiment we can determine the concentration of sodium hydroxide solution through titration technique using hydrochloric acid and sulfuric acid. The concentration of un/nown solution ! containing #a$ can be determined by using the titration of two different acids& !l and %,$- where when the titration of #a$ with !l& the concentration of solution ! or #a$ is *.-3% +& and the titration of #a$ with %,$- is *.-4- +. From this experiment ?e also can apply correct technique in titration and we were carry out acid base titration using phenolphthalein as indicator that will change the colourless solution into pin/ color.
RE>ERENCES:
). Brown& 6emay& Bursten& +urphy ')744%**7( !hemistry: The !entral ,cience 2leventh 2dition. @nited ,tates $f America. earson 2ducational >nternational. %. http:en.wi/ipedia.orgwi/iAcidbasetitration
UNIVERSITI PENDIDI?AN SULTAN IDRIS
>UNDAMENTAL CHEMISTR@ (T?U !*33)
EXPERIMENT 2: ACID AND BASE TITRATION
NAME: NURHASNI BINTI MARU> MATRIC NUMBER: D2**!*32363 LECTURERS NAME: PUAN >ARIDAH BINTI @USO> SESSION: 29** PM 9** PM (MONDA@) ROUP : 2
