QUANTITATIVE ANALYSIS OF SODA ASH BY D DOUBLEINDICATOR TITRATION E.P. MUNCAL
AND
J.N. GRAGEDA
EPARTMENT OF F OOD SCIENCE AND CIENCE AND NUTRITION, COLLEGE OF H DEPARTMENT OF F OOD HOME ECONOMICS NIVERSITY OF THE THE PHILIPPINES, DILIMAN, QUEZON CITY , PHILIPPINES UNIVERSITY OF ATE PERFORMED: M ARCH 1, 2016 D ATE YLE BENITO INSTRUCTOR’ S N AME: K YLE
1. Why Why is h!"! h!"! # $!!% $!!% & '&i( '&i( h! h! %is %isi( i((! (!% % )#! )#!" " i$ h! h! *"!*#"#i&$ &+ '#s! s&(,i&$ The distilled water should be boil boiled ed to remov emove e the the carb carbon on dioxide in it since it can reach with water to produce carb carbon onat ate e whic which h can can act act as a 1 bufer. . Why Why is h! /i0 /i0," ,"! ! &+ N#OH N#OH #$% N#HCO i$2&/*#i'(! Since Since NaOH NaOH is a strong strong base and NaHCO NaHCO3 is an amphot amphoteri eric c salt the reaction o! the two will produce produce a carbonat carbonate e ion. "!ter the reaction there will be less h#droxide le!t and there!ore the components o! the solution will not be distinguishable. 1 . Why Why is h!"! h!"! # $!!% $!!% & '&i( '&i( h! s&(,i&$ '!+&"! "!#2hi$3 h! /!hy( &"#$3! s&(,i&$ Since Since the the titrat titration ion produ produces ces a Carbon dioxide b# product. This compound could possibl# inter! inter!er ere e with with the accura accurac# c# o! the values values garn garner ered ed !rom !rom the experiment since it can act as a bufer when it becomes carbo carbonat nate. e. $# boilin boiling g most most o! the carbon diox ioxide will be removed thus ma%ing the accura accurac# c# o! the the volume volumes s used used higher. 4. Dis2,ss h! '#si2 2&/*&$!$s &+ h! ,$5$&)$ s&%# s& %# #sh #sh s#/* s#/*(! (! '#s! '#s!% % &$ h! 6&(,/ 6&(,/! ! "!(# "!(#i&$ i&$sh shi* i* # •
h! h! *h!$&(* &(*hh hh#(! #(!i$ #$% #$% /!hy( &"#$3! !$%*&i$s. &n all o! the titrations made the volu volume me neede eeded d to reach each the the meth meth#l #l oran range end poin pointt is alwa alwa#s #s lar larger ger relat elativ ive e to the the ones needed !or the phe phenolp nolph hthal thalei ein n endpo ndpoiint. nt. "ccording to this the soda ash sample is composed o! NaHCO 3 and Na'CO3. 7. Is i *&ss *&ssi'( i'(! ! & ,s! ,s! N#OH N#OH #s h! h! *"i/ *"i/#" #"y y s#$ s#$%# %#"% "% +&" +&" HC( " primar# should not be h#gr h#gros osco copi pic c must must have have high high mola molarr mass mass and and poss posses esse ses s a %now %nown n react eactio ion. n. NaOH NaOH migh mightt have a predictable reaction but it is highl# h#groscopic h#groscopic and light in mola molarr mass mass and and ther thereb eb# # it cann cannot ot be used used as a prim primar ar# # standard. 8. Dis2,s Dis2,ss s h! *"&*! *"&*!"i "i!s !s &+ #$ i%!#( *"i/#"y s#$%#"%. " primar# primar# standar standard d should should not be h#groscopic since it needs to be highl# pure upon standardi(ation. " highl# h#groscopic chemical cannot be used us ed as a prim primar ar# # stan standa darrd since it attracts moisture in its surroundings and b# this characteristic its purit# ' becomes lesser. &t should also have a high molar mass so that it can be measure ured accuratel# with ' minimal errors. •
The reaction o! the standard standard with ith the the titr itrant shoul hould d also also predictable so that it is eas# to predict the possible products o! the titration. ' 9. E0*(#i E0*(#i$ $ h! "#i&$# "#i&$#(! (! '!hi$% '!hi$% $& s&"i s&"i$3 $3 '#si2 '#si2 s&(,i s&(,i&$s &$s i$ 6&(,/!"i2 3(#ss)#"!. $asic solutions are not stored in volumetric glassware beca becaus use e it will will react eact with with the the silic ilica a which ich compo ompos ses the the glass glass to !orm !orm sodiu sodium m silic silicate ate.. This reaction can destro# destro# the insides o! the glassware. 1 :. Dis2,ss Dis2,ss h! *&ssi *&ssi'(! '(! s&,"2 s&,"2!s !s &+ !""&"s #$% h!i" !;!2s &$ 2#(2,(#!% *#"#/!!"s. One o! the possible sources o! errors is the wrong execution o! the procedures. )or instance i! the prepared solutions exceeded the expected conc concen entr trat atio ion n the the valu values es !or !or the endpoints will become erroneous. *oreover the volu volume mes s accou ccount nted ed !or !or the titrat titration ion will will also also wrong wrong i! the amount o! titrant in the burette had not been correctl# measured or when the titration process starts and the amount o! titrant in the burette was not
recorded the correct amount o! titrant will not be determined. <. Dis2,ss h! 2#,s! &+ 2#"'&$#! !""&" #$% is !;!2 &$ h! 2#(2,(#!% 6#(,!s &'#i$!% i$ h! s#$%#"% s#$%#"%i=# i=#i&$ i&$ #$% s#/*(! s#/*(! #$#(ysis. The carbonate error afects the calculated values !or the stan standa darrdi(a di(ati tion on and and samp sample le anal#s anal#sis is since since it incre increas ases es the pH o! the samples to be anal#(ed thus needing more o! the titrant to reach end point. &t might increase or decrease the numb number er o! mol moles need eeded to reach the visible endpoint. 3
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