VOLUMETRIC ANALYSIS
1. A is 0.125mol/dm3 of
H2SO4. B is a solution
containing xgdm^-3 of
NaOH.
(a.) Put A into the burette
and titrate it against
20.0cm3 or 25.0cm3 portion
of B using Methyl Orange
as indicator.
Record the volume of your pipette.
Tabulate your burette
readings and Calculate the average volume of A
used.
THE EQUATION FOR THE
REACTION IS H2SO4(aq) + 2NaOH -->
Na2SO4 + 2H2O
From Your result and
Information provided
above, Calculate
(i) the amount of H2SO4 in
the the average volume of
A used.
(ii) Concentration of B in
mol/dm3
(iii) Value of X.
[H=1,O=16,Na=23]
SOLUTIONS
The Equation for the
Reaction: H2SO4(aq) +
2NaOH --> Na2SO4 + 2H2O
TABLE OF VALUE
Bur Rd|Rough|1st|2nd |3rdFinal|24.00|24.30|
29.30|34.30
Initial|0.00|0.00 |5.00 |10.00
Vol. |24.00|24.30|24.30|
24.30
NOTE: Rough,1st titre,2nd
titre,3rd titre are all in
(cm3)
AVERAGE VOLUME OF ACID USED
= 24.30+24.30+24.30/3
= 72.9/3
=24.30.
(Bi) A contains 0.125mol/
dm3 of H2SO4(given) ie
0.125 in 1000cm3 of H2SO4
.:. X in 24.30; X =
24.30/1000 * 0.125
= 0.00303
= 0.003 mol per 24.30cm3.
(ii) Conc of A * Vol of A/
Conc of B * Vol of B =nA/nB
ie CAVA/CBVB = nA/nB
= 0.125*24.30/CB*25 = 1/2
CB = 6.075/25
= 0.243
= 0.24mol/dm3.
(iii) B contains Xgdm3 of
NaOH, Molar Mass of NaOH
= 40g.
Mass Conc = Mole
Concentration * Molar Mass
= 0.243 * 40
= 9.72g
======================
=======================
SALT ANALYSIS br /> 2.
(a) TEST Xn +
Distilled H2O
OBSERVATION:
White ppt, colourless
solution observed.
INFERENCE Soluble
Salt
=======================
(i) *TEST Filterate
+ BaCl2 + Dil HCl in excess.
*OBSERVATION
White ppt formed.
Precipitate Insoluble.
*INFERENCE:
SO4^2-,SO3^2-, CO3^2-
Present.
=======================
TEST:
Residue + dilute HCl
OBSERVATION:
Effervescence gas
evolved.
An odourless gas.
Deep blue ppt.
INFERENCE: Cu^2+ Present.
=======================
TEST:
Filterate + HNO3 + AgNO3
+ NH3
*OBSERVATION
No visible reaction.
White ppt formed.
Ppt dissolved in excess
NH3(aq)
*INFERENCE Cl^-
present.
Cl^- confirmed.
=======================
(bi) TEST Filterate
+ BaCl2 + dil HCl
*OBSERVATION br />
White ppt remained
insoluble.
*INFERENCE: CO3^2-,
SO4^2- Present.
=======================
(ii) TEST A portion
of (bi) + NaOH solution
dropwise and in excess.
*OBSERVATION:
A light blue ppt insoluble in
excess of NaOH Solution.
*INFERENCE Cu^2+
present
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