Grade 12 Titration Stellenbosch Version Prac Sheet ONLY

 

 

SU$C OI

Stellenbosch University Chemistry Outreach Initiative  in collaboration with the WCED 1

Grade 12 Practical !earner "and# out The titration of oxalic acid against sodium hydroxide

$ame Date "i%h School

[1]

MZ Moera Moerat, t, Subj Subject ect Adviso Advisorr Physi Physical cal Scienc Sciences, es, Western estern Cape Cape Educa Educatio tion n epart!ent, Moha!!ed"Moerat#$esterncape"%ov"&a Moha!!ed"Moerat#$esterncape"%ov"&a

 

&'() O*+'I$ED O*+'I$ED

,-.

Titration of oxalic acid against sodium hydroxide. SAFETY: 1.

Ox Oxal alic ic ac acid id is co corr rros osiv ive. e. It ca can nb be e ffat atal al if swal swallo low wed ed..

2.

So Sodi dium um h hy ydrox droxid ide e is po pois ison onou ous, s, h har armfu mfull if in inha hale led, d, bur burns ns tthe he skin skin an and d it may be fatal if swallowed.

3.

ll ll c che hemic mical als sa are re ha ha!a !ard rdou ous. s. " "le leas ase ec con onsu sult lt y you ourr la labo bora rato tory ry m man anua uall fo for  r  more mo re info inform rmat atio ion n ab abou outt wh why y ox oxal alic ic ac acid id,, so sodi dium um hy hydr drox oxid ide e an and d sulphuric acid are ha!ardous.

#.

$e $ear ar sa safe fety ty % %o% o%%l %les es a and nd %lov %loves es w whe hen n ha hand ndli lin% n% ch chem emic ical als. s.

Formal experiment 1: Titration Aim &etermine &eterm ine the con concen centra tratio tion n of a %iv %iven en sod sodium ium hy hydro droxid xide e sol solutio ution n of unk unknow nown n concentration by titration a%ainst a standard solution of Oxalic acid. Apparatus 'ou will need the followin% items for this experiment( • • • • • • • • • • • • • • •

),1 mol.dm*3 Oxalic acid +standard solution -aO solution +unknown concentration "henolphthalein indicator  &istilled water  "ipette of volume 2/ ml 0eakers, volume 2/) ml and 1)) ml 0alance Spatula rlenmeyer flask, volume 2/) ml olumetric o lumetric measurin% flask, volume 1)) ml "iece of paper  etort stand with base, retort clamp 0urette, volume /) ml $ash bottle &ropper 

Method '

 

1 "ipe "ipette tte 2/ml of th the e stand standard ard aci acid d solut solution ion into an  rlenme rlenmeyer yer flas flask k and add 3 drops of phenolphthalein indicator. 2 i ins nse e yo your ur bu bure rett tte e on once ce wi with th dist distill illed ed wat water er an and d th then en wi with th sm smal alll +/ +/*1 *1) ) ml portions of the -aO solution you have prepared, drainin% off the solution throu%h the burette tip. 3 4hec 4heck k if your burett burette e drains pro properly perly,, no air bubbl bubbles es are trapp trapped ed in the tip and no leaks are apparent. # 5il 5illl the bure burette tte to the !ero mar mark k with the -aO -aO  solut solution ion and mak make e sure that the burette tip is full of solution. $ith a piece of paper towel, remove any drop of -aO han%in% from the tip. / 6ake a pre prelimina liminary ry titrati titration on to learn ap approx proximately imately h how ow the titrat titration ion proc proceeds eeds.. "lace a piece of white paper under the flask so that the colour of the solution is easily observed. Swirl the flask and add the -aO solution. Occasionally rinse down the walls of the flask with distilled water from your wash bottle. 7itrate until the last drop of -aO solution leaves a permanent pink colour in the solution. ead and record the position on the burette of the lowest point of  the meniscus of the -aO solution. 8 the -o -ow wburette ti titr trat ate e is atrefilled llea east st three  more standard acid,and bein% that to the !ero samples mark withof-aO solution thatcertain you use a clean flask. 9 In this and su subse: bse:uent uent run runs s you may ad add d -aO solu solution tion fro from m the burett burette e very rapidly up to about 2 ml of the volume you estimate on the basis of your first titration. 7hen carefully add the rest of the base drop by drop so that you can determine the endpoint accurately accurately.. ; eco ecord rd the result results s in a table. &eci &ecide de which v values alues are ac accurat curate e and calc calculate ulate the the av aver era% a%e e vo volu lume me of -a -aO O us used ed..