D. Gevaña/ Chemistry 26.1 (2017)
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COMMON ION EFFECT AND BUFFERS D. Gevaña1 1
Electrical and Electronics Engineering Institute, College of Engineering, University of the Philippines, Diliman, Quezon City 1101
Performed 08 e!r"ary 2017# $"!mitted 1% e!r"ary 2017
Methodology Results and Discussion
&'sers to "estio's 1. &**o"'t for the di+ere'*es i' *o,or of $o,"tio's 1 a'd 2 after addi'g methy, ora'ge i'di*ator. -ethy, ora'ge i'di*ator is a i'di*ator that is "sed to test if a so,"tio' is a*idi*. ed i'di*ates a ra'ge of ,ess tha' .1 a'd as rises it t"r's ye,,o 3%4. 5he di+ere'*e i' *o,or of so,"tio' 1 (CC) a'd so,"tio' 2 (CC aCC) is a**o"'ted for its *omositio'. at"ra,,y so,"tio' 1 o",d aear redder as *omared to so,"tio' 2 hi*h aeared ye,,o as the former is a' a*id therefore o",d !e e9e*ted to have a ,oer . $odi"m a*etate is the *o':"gate !ase of a*eti* a*id a'd as !oth are mi9ed 'at"ra,,y so,"tio' 2 o",d have a higher as *omared to "re a*eti* a*id therefore e9"di'g a ye,,o *o,or "o' additio' of methy, ora'ge 34. 2. &**o"'t for the di+ere'*es i' *o,or of $o,"tio's a'd ; after addi'g he'o,htha,ei' i'di*ator. Phe'o,htha,ei' is a i'di*ator "sed to test !asi*ity of so,"tio's. <' so,"tio' 1 it *o'tai's a ea= !ase. 5herefore it e9*,"ded a' i'te'se i'= *o,or 3%4. oever i' so,"tio' ; as added ith ;C,. ;C, is formed from the rea*tio' of a ea= !ase a'd stro'g a*id. ;C, therefore is the *o':"gate a*id of hi*h therefore e9,ai's hy so,"tio' ; has a a,er i'= *o,or *omared to so,"tio' . 5herefore so,"tio' ; is e9e*ted to have a ,oer *omared to so,"tio' d"e to the rese'*e of a' a*id 34. . >hi*h *a"ses a ,arger *ha'ge i' additio' of dros of 1.0 - C, (or dros of 1.0 - a) to $o,"tio' 1 2 or ;? @9,ai'. 5he di+ere'*e "o' addi'g dros of a or C, may !e see' i' !"+er so,"tio's s"*h as so,"tio's 2 a'd ;. $ay i' so,"tio' 2 hi*h is a mi9t"re of a*eti* a*id a'd its *o':"gate !ase sodi"m a*etateAA if there is a greater amo"'t of a*eti* a*id tha' sodi"m a*etate it i,, have a greater !"+eri'g *aa*ity agai'st added a tha' C, a'd this hae's vi*e versa he' there is more sodi"m a*etate tha' a*eti* a*id. 5his a,so hae's i' so,"tio' ; hi*h is a mi9t"re of a'd its *o':"gate a*id ;C, 34. ;. Comare the di+ere't methods of determi'i'g B vis"a, i'di*ators meter a'd *a,*",atio's. Comare the a**"ra*y of the three methods em,oyed. is"a, is"a, i'di*ators i'di*ators s"*h as a*idA!ase a*idA!ase i'di*ators i'di*ators ma=e ma=e "se of 'at"ra, 'at"ra, dyes that e9ist as ea= a*id i' estimati'g the ra'ge of a so,"tio' 34. <' estimati'g the ra'ge of a so,"tio' the *o,or that is see' is the res",t after the so,"tio' has rea*hed e"i,i!ri"m. $e*iE* i'di*ator dyes are "sed to determi'e !asi* a*idi* a'd "'iversa, so,"tio's 314. meters are high,y se'sitive i'str"me'ts for ote'tiometri* a'd meas"reme'ts 34. Ca,*",ati'g for the theoreti*a, is o'e mea' of redi*ti'g or meas"ri'g the of a *ertai' s"!sta'*e. >he' *omari'g the a**"ra*y of the three methods em,oyed "si'g the meter is the most eF*ie't i' meas"ri'g the of a s"!sta'*e !e*a"se it gives the o!server a
D. Gevaña/ Chemistry 26.1 Page | 2 (2017) '"meri*a, va,"e of " to fo"r de*ima, ,a*es of the he or she 'eeds. oever the rearatio' a'd roer mai'te'a'*e i' "si'g a meter is tedio"s a'd there are a ,ot o f *o'sideratio's to !e made to e's"re a**"ra*y of data a'd to avoid erro'eo"s va,"es. -oreover it is a' e9e'sive devi*e. si'g i'di*ators is 'ot eF*ie't e'o"gh i' meas"ri'g a s"!sta'*eHs as it o',y gives a ra'ge. Ca,*",ati'g for the theoreti*a, is 'ot eF*ie't as e,, si'*e this is o',y a hyotheti*a, va,"e 'ot the a*t"a, va,"e. %. >hat are the ossi!,e so"r*es of errors a'd their e+e*t o' the *a,*",ated arameters? atio'a,iIe. &'y *rysta,s i' the refere'*e *omo'e't of a *om!i'atio' e,e*trode *a' *a"se ro!,ems !y *,oggi'g the :"'*tio'. 5his may ,ead to erro'eo"s va,"es d"ri'g the meas"ri'g of the of the sam,es. >he' the meter is 'ot *a,i!rated roer,y !efore meas"ri'g the of the sam,es. <' rea,ity the e,e*trode might rod"*e res",ts that are s,ight,y di+ere't from the theoreti*a, !ehavior. Ca,i!ratio' of the meter *ome'sates for this !y determi'i'g the a*t"a, s,oe a'd o+set of the e,e*trode !y "si'g !"+er so,"tio's a'd "dati'g the setti'gs (!"+er *o'tro, a'd s,oe *o'tro,) of the meter a**ordi'g,y 324. >ii'g the se'si'g g,ass of the e,e*trode. <' doi'g so the a*tivity *a' rod"*e a stati* *harge. 5he stati* *harge i'terferes ith the vo,tage readi'g of the e,e*trode 324. $im,y !,otti'g the e'd of the ro!e ith a tiss"e or *,oth i,, remove dro,ets itho"t a+e*ti'g the e,e*trodeHs se'sitivity. 5he e,e*trode is 'ot ri'sed ith disti,,ed ater i' !etee' ea*h meas"reme't. Deosits may form o' the e,e*trode *oat a'd th"s as a res",t the meter i,, !e meas"ri'g the deosits a'd the sam,e rather tha' :"st the sam,e. 5his m ay ,ead to *o'tami'atio' of so,"tio's a'd i'a**"rate res",ts. <'ade"ate ro!e s"!mersio' may ,ead to erro'eo"s va,"es. 5he ro!e m"st !e *om,ete,y s"!merged i' the so,"tio' i' order to roer,y f"'*tio'. 5he meter m"st !e stored i' a room ithi' its se*iEed temerat"re ra'ge. D"ri'g the e9erime't the room i' hi*h the meter as stored i' as re,ative,y hot. 5his *a' a+e*t severa, e"i,i!ria givi'g ri se to *om,i*ated meas"reme't errors.
References 314 Jr"''i'g &'dy. K5he Co,o"rs L Chemistry of P <'di*ators.K Compound Interest . .. 1 -ay 201%. >e!. 12 e!. 2017. 324 KP -eters a'd 5heir @,e*trodesB Ca,i!ratio' -ai'te'a'*e a'd se.K P !eters and "heir Electrodes# Cali$ration, !aintenance and Use ('.d.)B '. ag. I%!&. <'stit"te of Jiomedi*a, $*ie'*e &r. 201. >e!. 12 e!. 2017. 34 <'stit"te of Chemistry. Chem '()1# *nalytical Chemistry +a$oratory !anual. 'iversity of the Phi,ii'es Di,ima'. 2017. Pri't. 3;4 <'str"me'ts a''a. K5o 10 -ista=es i' P -eas"reme't.K anna Instruments %log. a''a <'str"me'ts 20 &r. 2016. >e!. 12 e!. 2017. 3%4 $=oog Do"g,as &. Do'a,d -. >est . Mames. o,,er a'd $ta',ey . Cro"*h. undamentals of *nalytical Chemistry . Nth ed. Je,mo'tB Jroo=s/Co,e Ce'gage Oear'i'g 201. Pri't.
