11.1 pag

PAG 11.1 pH-Problem Solving Introduction:  This investigation will be to test test  given un!nown colourless solutions solutions o" either acids# bases or a bu$er solution which will be tested until identi%ed. Aim:  The aim o" this investigation is to test the given solutions solutions using various di$erent di$erent methods until each is identi%ed as one o" the "ollowing: 1. '. *. ,. 0. . .

Ammo Ammoni niaa- pH & 1 11 1 (tha (thano noic ic Aci Acidd- pH &'. &'.)) )) (thano (thanoate ate +u$er +u$er-- pH &,. &,. Hdro Hdrochl chlori oric c Acid Acid-- pH &1./) &1./) Sul"ur Sul"uric ic 2I3 2I3 Ac Acidid-pH pH &1./ &1./1 1 4ethan 4ethanoic oic Ac Acidid- pH &'.*) &'.*) Sodium Sodium Hdro Hdro5id 5idee- pH&1' pH&1'.)) .))

4ethod: 1. 6a"ti a"ting ng Test est a3 ta!e ta!e each solution solution and and open open the container container b3 holding holding it near near nose# pass pass air air using hand towards towards nose c3 note note obse observa rvatio tions ns in tabl table e '. Phenolphtha Phenolphthalein lein Indicator Indicator Test a3 label  wells p" p" spotting spotting tile tile as solutions solutions A-G A-G b3 add ' drops o" each each solution solution using dropping dropping pipettes pipettes to to the wells under under its label c3 add 1 drop drop o" phenolpht phenolphthalein halein using a dropping dropping pipette pipette each each well d3 note note obser observat vation ions s in tabl table e e3 note note i" basic basic i" solutio solution n turned turned pin! pin! *. Testing pH 2alues 2alues o" o" +ases with with pH 4eter 4eter a3 7alib 7alibra rate te pH pH mete meter: r: Place probe into a pH  bu$er solution and measure pH o 8sing a screw driver# move screw until pH measure me asure is e5actl  o 9inse probe a"ter use o Place probe into a pH 1/ bu$er and measure pH o 8sing a screw driver# move screw until pH measure me asure is e5actl 1/ o b3 test pH pH o" the the solutions solutions identi%ed identi%ed as basic c3 reco record rd val value ues s in tab table le ,. Testing pH 2alues 2alues o" 9emainin 9emaining g Solutions Solutions with pH 4eter 4eter a3 7alib 7alibra rate te pH pH mete meter: r: Place probe into a pH  bu$er solution and measure pH o 8sing a screw driver# move screw until pH measure is e5actl  o 9inse probe a"ter use o Place probe into a pH , bu$er and measure pH o 8sing a screw driver# move screw until pH measure is e5actl , o b3 Test pH pH o" remaini remaining ng solution solutions s c3 9ecord ecord val value ues s in tab table le 0. Titra itrati tion on

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PAG 11.1 pH-Problem Solving a3 label  test tubes A-G b3 place *cm o" each solution into test tube o" its label c3 add ' drops o" phenolphthalein indicator to each test tube bases should turn pin! while acidic solutions remain colourless3 d3 per"orm titration using H7 "or solutions "ound to be basic and ;a
9esults Table:

Soluti on

Smell

Observatio ns with Phenolphth alein

Basi c?

pH Valu e

Number of drops till pH change

A

;o smell

;o change

;o

1.,0

Av=

Sul"uric acid

+

Punge nt smell

7olour change to pin!

 >es

11.0

Av=

Ammonia

7

6ea! smell

;o change

;o

1.'

Av=

Hdrochlo ric acid

?

;o smell

7olour change to pin!

 >es

1*.0@

Av=

Sodium hdro5ide

(

2ineg ar smell

;o change

;o

'.)

Av=

(thanoic acid



2ineg ar smell

;o change

;o

'.@/

Av=

(thanoat e bu$er

G

;o smell

;o change

;o

'.*)

Av= 1

4ethanoi c acid

1 

1 0

Identity

(Buipment:

pparatus pH meter

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!usti"cation To measure the pH o" the un!nown

PAG 11.1 pH-Problem Solving

Glass bea!ers ?ropping pipettes  Test tubes  Test tube rac! Spot tile ?istilled water in wash bottle Phenolphthalein indicator solution /., moldm H7l aB3 /., moldm ;a
solutions to identi" them To wash and hold pH probe To trans"er solutions and use in hand titration To separate solutions "or titrations To hold test tubes during titrations To separate solutions during phenolphthalein test To wash pH probe between uses To measure i" solution is basic To use in hand titration o" bases To use in hand titration o" acids

9is! Assessment: 7hemicals Phenolphthalein indicator solution /.1D3

HaCard Highl Eammable# ee irritant and carcinogenic i" ingested.

/., moldm ;a
S!in irritant and serious ee irritant.

/., moldm H7l aB3

ow haCard /.3 but ma cause irritation to ees and s!in.

Solutions A-G

S!in and ee irritant.

Apparatus

HaCard

Glassware

I" bro!en can cause cuts.

iBuids

I" spilt can cause irritation to s!in# ees and respirator sstem and slips.

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4anagement 6ear ee protection and lab coats. Feep awa "rom an sources o" ignition. 6ash hands and wipe sur"aces a"ter use. 6ear ee protection and lab coats. 6ash hands and wipe sur"aces a"ter use. 6ear ee protection and lab coats. 6ash hands and wipe sur"aces a"ter use. 6ear ee protection and lab coats. 6ash hands and wipe sur"aces a"ter use.

HaCard in Procedure 6hen trans"erring liBuids# washing and transporting liBuids.

6hen being trans"erred or washing apparatus.

4anagement 8se care"ull in isolated area to minimise potential accidents. Have bro!en glass !it and %rst aid !it easil accessible. 8se care"ull and wipe up an spills immediatel. Have chemical spill !it# ee wash and %rst aid !it

PAG 11.1 pH-Problem Solving easil accessible. 9e"erences: (5tension uestions:

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