final revision

1. YOU TUBE CHANNEL:
KNOW THE CHEMISTRY
BY RAJIV JAIN

2. THOUGHT FOR THE SESSION

3. HYDROGEN
CHLORIDE

6. FOUNTAIN EXPERIMENT

9. REACTIONS OF dil HCl ACID
Mg + 2HCl  MgCl2 + H2
NH3 + HCl  NH4Cl
ZnO + 2HCl  ZnCl2 + H2O
NaHCO3+HClNaCl +H2O + CO2

10. REACTIONS OF dil HCl ACID
KHSO3+ HCl  KCl + H2O + SO2
ZnS + 2HCl  ZnCl2 + H2S
Na2S2O3 + 2HCl 
2NaCl + H2O + SO2 + S
Pb(NO3)2+ 2HCl  PbCl2 ↓+ 2HNO3
AgNO3 + HCl  AgCl ↓ + HNO3

11. REACTIONS OF Conc. HCl

12. REACTIONS OF Conc. HCl v. imp
2KMnO4 + 16 HCl (conc) 
2 KCl + 2 MnCl2 + 8 H2O + 5 Cl2
MnO2 + 2 HCl (conc)  MnCl2 + 2 H2O + Cl2
Pb3O4 + 8 HCl (conc) heat 
3 PbCl2 + 4 H2O + Cl2

13. Test for HCl
 BLUE Litmus RED / pH PAPER /
INDICATORS (phenolpthalein/ methyl
orange/ alkaline phenolpthalein)
 AgNO3 TEST / WHITE PPT
 AMMONIA SOLUTION TEST / DENSE
WHITE FUMES OF AMONIUM CHLORIDE
 PUNGENT CHOCKING ODOUR
 COLOULESS GAS/ LIQUID IF
HYDROCHLORIC ACID

14. IMPORTANT QUESTIONS ON HCl

15. Q1. This gas produces dense white
fumes with ammonia gas.
Ans1. Hydrogen chloride gas
Q2. Identify the acid. “The acid on
mixing with silver nitrate solution
produces a white precipitate which
is soluble in excess ammonium
hydroxide”.
Ans2. Hydrochloric acid

16. Q3. The following questions are
pertaining to the laboratory
preparation of hydrogen chloride gas.
(i) Write the equation for its preparation
mentioning the condition required.
NaCl + H2SO4 Conc T< 2000C 
NaHSO4 + HCl
(ii) Name the drying agent used and
justify your choice.
Conc H2SO4

17. Q3. The following questions are
pertaining to the laboratory
preparation of HCl
(iii) State a safety precaution you
would take during the
preparation of hydrochloric acid.
Temperature of the reaction
mixture is less than 2000C

18. Q4. Fill in the blanks:
(i) Quicklime is not used to dry HCl gas
because __ (CaO is alkaline, CaO is acidic
, CaO is neutral) alkaline

19. Q5. State one appropriate observation for
each of the following:
(i) Copper sulphide is treated with dilute
hydrochloric acid.
Colorless rotten egg gas evolved which turns
moist lead acetate paper black.
(ii) A few drops of dilute hydrochloric acid
are added to silver nitrate solution,
followed by addition of ammonia
hydroxide solution.
Curdy white ppt formed which dissolved in
ammonium hydroxide solution.

20. Q6. Give balanced equations
for the following reactions:
(i)Concentrated hydrochloric
acid and potassium
permanganate solution
Ans 2KMnO4 + 16 HCl conc 
2 KCl + 2 MnCl2 + 8H2O + 6Cl2

21. DIAGRAM: lab preparation OF HCl

22. Q7. In the laboratory preparation of
hydrochloric acid, HCl gas is dissolved
in water.
(i) Draw a diagram to show the
arrangement used for the absorption of
HCl in water.
(ii) Why is such an arrangement
necessary? Give two reasons.
Ans. Inverted funnel arrangement , To
prevent the back suction . To make
hydrochloric acid and to prevent any
accident.

23. Q7. In the lab preparation of hydrochloric
acid, HCl gas is dissolved in water.
(iii) Write the chemical equations for
the lab preparation of HCl gas when the
reactants are: (A) Below 2000C (B)
Above 2000C
NaCl + H2SO4 Conc T< 2000C 
NaHSO4 + HCl
2NaCl + H2SO4 Conc T > 2000C 
Na2SO4 + 2HCl

24. Q8. The diagram shows an apparatus for
the laboratory preparation of hydrogen
chloride. (i) Identify A and B.
Ans. conc sulphuric acid, sodium chloride
(ii) Write the equation for the reaction
NaCl + H2SO4 Conc T< 2000C 
NaHSO4 + HCl

25. Q8. The diagram shows an apparatus for the lab
preparation of hydrogen chloride.
(iii) How would you check whether or not the
gas jar is filled with hydrogen chloride?
Ans. A rod dipped in ammonium hydroxide is
brought near
the mouth of
the collecting
jar. Dense
white fumes
signifies the
gas is filled.

26. Q8.
(iv) What does the method of collection
tell you about the density of hydrogen
chloride?
Ans It is heavier than air.

27. Q9. Write a fully balanced equation
for each of the following cases:
(i)Red lead is warmed with
concentrated hydrochloric acid.
Ans. Pb3O4 + conc 8HCl 
3PbCl2 + 4H2O + Cl2
(i) Magnesium metal is treated
with dilute hydrochloric acid.
Mg + 2HCl  MgCl2 + H2

28. Q10. The diagram shows a simple arrangement
of the fountain experiment: [3]
(i) Name the two gases you have studied which
can be used in this experiment.
Ans, Ammonia, hydrogen chloride
(i) What is the common property demonstrated
by this experiment?
High solubility of
ammonia or
hydrogen chloride
in water.

29. Q11. (i) Of the two gases, ammonia
and hydrogen chloride, which one
is more dense? Name the method
of collection of this gas.
Ans. Hydrogen chloride , upward
displacement of air.
(ii) Give one example of a reaction
between the above two gases,
which produces a solid compound.
NH3 + HCl  NH4Cl

30. Q12. Write balanced equations for the
reaction of dilute hydrochloric acid
(i)Iron
Fe + 2HCl  FeCl2 +H2
(ii) Sodium hydrogen carbonate
NaHCO3 + HCl  NaCl + H2O + CO2
(iii) Iron (II) sulphide
FeS + 2HCl  FeCl2 +H2S

31. Q12. Write balanced equations for the
reaction of dilute hydrochloric acid
(iv) Sodium sulphite
Na2SO3 + 2 HCl 
2NaCl +H2O + SO2
(v) Sodium thiosulphate solution
Na2S2O3 + 2 HCl 
2NaCl +H2O + SO2 +S

32. Q13.A solution of hydrogen chloride in water is
prepared. The following substance are added to
separate portions of the solution:
S.
No.
Substance added Gas evolved Odour
1 Calcium carbonate with
dil HCl
2 Magnesium ribbon with
dil HCl
3 Manganese (IV) oxide
with conc HCl
4 Sodium sulphide with dil
HCl

33. ANS13
S.
No.
Substance added Gas evolved Odour
1 Calcium carbonate
with dil HCl
Carbon
dioxide
Odourless
2 Magnesium ribbon
with dil HCl
Hydrogen Odourless
3 Manganese (IV)
oxide with conc HCl
Chlorine Pungent
chocking
4 Sodium sulphide with
dil HCl
Hydrogen
sulphide
Rotten egg

34. Q14. What must be added to sodium
chloride to get hydrogen chloride?
Ans14. Conc sulphuric acid
Q15. What would you see when
hydrogen chloride mixes with
ammonia?
Ans15. Dense white fumes of
ammonium chloride.

35. Q16. Write equation for the reaction
of hydrochloric acid with
(i) lead nitrate
Pb(NO3)2 + 2HCl  PbCl2 +
2HNO3
(ii) manganese (IV) oxide.
MnO2 + 4HCl (conc)  MnCl2
+ 2H2O + Cl2

36. Q17. From the following list choose the
correct answer: Ammonium hydroxide ,
ammonium nitrate, chlorine, dilute
hydrochloric acid, iron, lead nitrate,
manganese (IV) oxide, silver nitrate,
sodium nitrate, sulphur.
(i) A substance containing both molecules
and ions.
Ammonium hydroxide
(ii) two compounds whose aqueous solution
gives white precipitate with dilute
hydrochloric acid.
Ammonium hydroxide, silver nitrate solution

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