Day
: Monday
Date
: July 10th, 2006
Name : -------IC : -------Class : Lower Six Science Experiment 1 Topic
:
Volumetric analysis – Acid ase
Purpose
:
!etermine the exact concentration o" a mineral acid, #$%&, and to determine the relati'e atomic mass o" the element $
Materials
:
KA 1 is a material acid, #$%& KA 2 is a solution containin( 1)*0 ( o" %# - ions +er dm- henol+hthalein as indicator
Apparatus
:
.ea/er unnel etort stand and clam+ hite tile 230 cm4 conical "las/ 23 cm4 +i+ette i+ette "iller .urette %ne wash ottle with distilled water
Theory
:
An acid +roduces hydro(en ions which causes acidity) hile a solution which contains contains hydroxyl ions is an al/ali al/ali solution) solution) hen oth the solutions solutions are added to(ether oth the hydro(en ions hydroxyl h ydroxyl ions will react to "orm mater and this +rocess is called neutrali5ation) Procedure a
:
1) ara ara+h +her erna nali liaa neede needed d to ma/e ma/e the the ex+e ex+eri rime ment nt was was ota otain ined ed "rom "rom the the teac teacher her)) Laoratory (lassware was then rinsed with distilled water) 7his +rocedure ta/e +lace to assure that the a++aratus are in (ood and clean +osition + osition e"ore it is use to ma/e an ex+eriment) 2) Later Later on, a urett urettee was clam+ clam+ed ed to a retort retort stan stand) d) ) 7hen, 7hen, 8A 1 solutio solution n was "illed "illed into the urett urettee that was clam+ed clam+ed onto the retort retort stand care"ully to a'oid systematic error) A little o" 8A 1 solution was "low out o" the urette 9ust enou(h to dis+ose the ule o" air at the ottom o" o " the urette)
&) 7he 8A 1 solution meniscus le'el was ad9usted to a readin( 5ero) .y +uttin( the eye:s at the le'el o" the (raduation, the initial readin( o" 8A 1 solution in the urette was recorded in the result tale) 7his is to a'oid +arallax error) 3) ;sin( a 23)0 cm +i+ette, 8A 2 solution was trans"erred into a titration "las/) 6) ) hile the dro+s o" 8A 1 solution dro+ into titration "las/, the "las/ was swirl slowly until the colour o" 8A 2 solution in the "las/ chan(e "rom +in/ to +lain) 10) 7he sto+coc/ was ?uic/ly close to +re'ent the "low o" 8A 1 solution "rom comin( out 9ust a"ter the colour o" 8A 2 solution chan(e colour) 7he readin( was ta/en and then recorded in the result tale) 11) 7he +rocedure was re+eated "rom +rocedure 2 to +rocedure 10 aout two times 9ust necessarily to achie'e accurate results)
esults
@
:
ecord your titration readin(s in the tale elow)
Titration number
ou(h
Accurate
1
2
inal readin(cm4
23.90
23.80
23.90
24.00
Bnitial readin(cm4
0.00
0.00
0.00
0.00
23.90
23.80
23.8 0
24.00
Volume o" KA 1cm4 @i
23)0 cm4 o" KA 2 re?uired
@ ii
calculate your a'era(e titre 'alue showin( the suitale titre 'alues
2,)==
cm4 o" KA 1 "or a com+lete
reaction) that you use) 2,)>0 + 2,)=0 + 2,)=0 + 2&)00 &
!uestion
@c
=
2,)== cm
,
:
Calculate the concentration, in mol dm-, o" solution KA 2) Concentration o" 8A 2 Molar Mass o" solute
D 1)*0 ( dm- D 16 E 1 D 1* D 1* ( mol-1
Concentration o" 8A 2 in mol dm-
1)*0 =
1* =
0)1 mol dm
−,
∴ 7o (et mol dm- "rom ( dm-, we need to di'ide the concentration with relati'e atomic mass @Ar o" hydroxyl ions which is 1*) @d
rite a alanced ionic e?uation "or the reaction etween solution KA1 and solution KA 2) +
H
@ aq 6
+
−
OH
→
@ aq 6
H 2O @ li 6
∴
is reaction etween the hydro(en ions and the hydroxyl ions which the end +roduct will e water)
@e
Calculate the concentration, in mol dm-, o" mineral acid #$%& in solution KA 1) ∴ .y
which
usin( cross-multi+lyin( method, 23)0 cm o" al/ali 8A 2 solution which is 0)10 mol dm- needs 2)== cm o" acidic 8A 1 solution is Ma mol dm- to e neutrali5ed com+letely) M aV a M bV b
a =
b
M a x 2,)== cm 0)1 mol dm
−,
,
1
x 23)00 cm
,
=
1
0)1 x 23)0 M a =
M a
@"
=
2,)==
0)10&* mol dm
−,
B" the concentration o" mineral acid #$%& in solution KA 2 is 20)1 ( dm-, calculate the relati'e molecular mass o" #$%&) n
=
Mr
=
Mr
=
M M r M n
20 )1 0)10&*
= 1>1 )>= ∴ .y
( in mol
com+arin( the concentration in mol dm- with the concentration in dm- which has to e di'ided y the Mr to (et the concentration dm-, we will ale to "ind the M r y cross-multi+lyin()
@(
;sin( the answer to @", determine the relati'e atomic mass o" element $) elati'e atomic mass 1>1)>= $
= HXO &
(
= 1 + Χ + & 16
)
= 1>1)>= − 1 − 6&
= 126 )>=
the remo'in( the Ar o" @h
∴ 7he Mr o" #$%& is the summation o" all the relati'e atomic mass o" entire element which is hydro(en, $, and oxy(en) 7hus, y the other entire /nown element "rom the Mr , we will (et element $) Su((est an identity "or element $) Flement $ which ha'e Ar o" 126)>= is actually Bodine)
