class 12 chemistry viva questions salt analysis

1. MOST IMPORTANT
VIA Questions
CHEMISTRY Boardsus
PRACTICALS
·o
eRINGZEIFETIME
BMaval
Panemal Sir
& Bharat Panchal-Chemistry Gurujic.o

2. qualitative chemical analysis, branch of chemistry that deals with
the identification of elements or grouping of elements present in a
sample.
Negatively charged radicals are called acidic radicals. Positively charged
radicals are called a basic radical.
QI. what is Qualitative Analysis ?
Dw'
QI what are acidic radicals and basic radicals ?
Auf
NaOH + tell → May + tho
to I
G-
A A ☐ c.
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3. Due to the high dielectric constant of water, the force of attraction
holding the two ions in a salt decreases. Thus, the two ions
separate
Cu2+,Fe2+, Fe3+, Cr3+, Ni2+, Co2+ and Mn2+
Cu2+,Fe2+, Fe3+, Cr3+, Ni2+, Co2+ and Mn2+
03 .
why do
inorganic salts ionise when dissolved
in water ?
78-4
Aye
94.
Name the coloured basic radicals ?
A-
05.
Name the basic radicals which are absent if
the given salt is white.
At
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4. Due to the formation of black lead-sulphide by the action of
H2S in atmosphere
96 . Name the colour of iron and nickel salts .
AE feat →
light Green
Fest →
Brown
Mist→ Bluish Green
QF.
why a salt
containing lead turns black in
colour when placed for a
long time in lab?
¢146007,
Pb 1-
Hgs → pbste
lead sulphide
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cBlack in colour)
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5. Mg has very high ionisation energy it has one more proton in its nucleus
to hold on to the electrons in the 3s orbital, so it does not impart any
characteristic color to the Bunsen burner flame.
A flame test is an analytic procedure used in chemistry to
detect the presence of certain elements, primarily metal
ions, based on each element's characteristic emission spectrum.
98.
In the flame test Na impart yellow colour to
the flame while magnesium doesn't impart any
colour.
why?
Ay
QQ.
Write the chemistry of flame test ?
ay

6. 910.
why do we use conc. the in preparing
a paste of the salt
for flame test?
Auf
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7. This is because glass contains sodium silicate which imparts its
own golden yellow colour to the flame.
1) Platinum doesn't impart any color to the flame.
2) It is not oxidised under the high temperature of the flame from a bunsen burner.
3) It is almost chemically inert. Even at high temperatures, it remains unattacked
by free radicals / acid radicals.
911.
why can't we use glass rod instead of platinum
wire
for performing flame test ?
AE
912.
Why is Pt metal G.referred to other metals for
flame test ?
BE
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8. Because their ionisation energies are high, so they need large amount of
energy for the excitation of their valence electrons to higher energy level
which is usually not available in the bunsen flame. So they do not impart
any colour to the flame.
911 why do Barium salts not impart colour to
the flame immediately.
Argue.
What is Nessler 's Reagent & where is it
used !
Auf Solh of Mercuric iodide & potassium iodide
to
kg Hg I
G. used to check ammonium Fou em a sample
Ga a reddish brown pbtn formed

9. Gis
.
Name the acid radicals detected by dittlzsoy
Aug ( 0,2
-
→ carbonate
S2-
→ sulphide
SOI
-
→ sulphile
NO
,
-
→ Nitrile
916 . Name the acid radicals detected by conctksoy.
Ay a- → Chloride
☐g- → Bromide
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-
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No,
-
→ Nitrate
CH
>
COO
-
→ Acetate ion

10. When the salt is treated with HCl, during reaction HCl gas is also
given out along with the gas evolved by the salt. So the actual gas
cannot be identified whereas with H2SO4, no such problem arises
The white ppt. of CaCO3 changes into soluble calcium bicarbonate and the
milkiness, therefore, disappears.
Q -
a-Why dit Hasoy is preferred while testing acid
radicals over dit HU
Qiaowhat happens if excess of co
,
is passed
through time water.
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11. 9kgIs there
any gas other than co
,
which turns
lime water Milky
Avi 802
920.
All nitrates on
heating with conc.
tyson in
the presence of paper pellets evolve NO
, gas
what is the function of paper pellet.
KNO,
-1
Hgfdy
→ KHSO at HNO
,
UNO,
-1C → NO
,
+
Cq -1110
(paper
pellet) GoaBzown gas

12. 921 How is the
ring test performed for Nitrate.
Ay
ffectkos)gN0]S0y
f-

13. The chromyl chloride test is used to detect chloride ions in the
qualitative analysis. If any chloride salt like sodium chloride is
heated with acidified potassium dichromate it produces red
colour fumes of chromyl chloride. It confirms the presence of
chloride ions in that salt.
921.
What is chromyl chloride fest ?
Ay
Nall -1 Conc.
Hasoy +
Kira07 → GO
,
I
,
chromyl chloride
creddish Brown)
croak +
H2O →
Ha GOY
yellow
Hacroy -1 NaOH + @↳ cool,pb → Pbcroy
Yellow ppt
C lead chlorinate )

14. Nitric acid is generally not used for preparation of original
solution in analysis of basic radicals, because it is an oxidizing
agent which will convert all low oxidation cations into higher
one and these cations can not be recognised in presence of this
acid.
023.
why original solution is not prepared in cone.
tenors ?
HE HNO
,
+ Has → NO
,
-1110 +
S
C Yellow colloidal
s )
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15. 0,24.
Name group reagent for different groups.
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16. Question. What is the principle of volumetric analysis?
Answer. In volumetric analysis, the concentration of a solution is determined by
allowing a known volume of the solution to react, quantitatively with another
solution of known concentration.
Question. Burette and pipette must be rinsed with the solution with which they
are filled, why ?
Answer. The burette and pipette are rinsed with the solution with which they
are filled in order to remove any water sticking to their sides, which otherwise
would decrease the cone, of the solutions to be taken in them.
Question. Why a titration flask should not be rinsed ?
Answer. This is because during rinsing-some liquid will remain sticking to the
titration flask therefore the pipetted volume taken in the titration flask will
increase.
My =
Mak
Titration
flask
!
But T
o
←pipette

17. Question. What is a molar solution ?
Answer. A molar solution is a solution, a litre of which contains one gm-mole
of the substance. This is symbolised as 1M.
Question. What is titration ?
Answer. The process of adding one solution from the burette to another in the
conical flask in order to complete the chemical reaction involved, is known as
titration.
Pipette should never be held from its bulb, why ?
Answer. The body temperature may expand the glass and introduce an error in
the measurement volume.
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