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Acids, Bases & Salts (C)
Q.1. Write the balanced equations for the preparation of the following compounds (as the major
product) starting from iron and using only one other substance:
(i) Iron (II) chloride (ii) Iron (III) chloride (iii) Iron (II) sulphate (iv) Iron (II) sulphide.
Ans : - (i) Fe + 2HCl (dil) → FeCl2 + H2
(ii) 2Fe (heated) + 3Cl2 (dry) → 2FeCl3
(iii) Fe + H2SO4 (dil) → FeSO4 + H2
Δ
(iv) Fe + S → FeS
Q.2. Copy and complete the following table – Column 3 has the names of the gases to be prepared
using the substance you enter in Column 1 along with dilute or concentrated Sulphuric acid as
indicated by you in Column 2.
Column 1
Column 2
Column 3
Substance
reacted
Dilute or concentrated
with acid
Gas Sulphuric
acid
Hydrogen
Ans : Column 1
Column 2
Column 3
Substance reacted
Dilute or concentrated
with acid
Gas
Any active metal (Mg, Zn) except Na,
K, Ca and Pb
dil. H2SO4
Hydrogen
Na2CO3, NaHCO3
dil. H2SO4
Carbon
dioxide
Bleaching powder Sodium chloride
and Manganese dioxide
dil. H2SO4 conc. H2SO4 Chlorine
Q.3. Write the equations for the laboratory preparation of :
(i) Sodium sulphate using dilute Sulphuric acid.
(ii) Lead sulphate using dilute Sulphuric acid.
Ans : - (i) 2NaOH + H2SO4 (dil) → Na2SO4 + 2H2O
(ii) Pb(NO3)2 + H2SO4 (dil) → PbSO4 + 2HNO3.
Q.4. Write the equation for the laboratory preparation of the following salts using sulphuric acid:
(i) Iron II sulphate from iron.
(ii) Copper sulphate from copper.
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(iii) Lead sulphate from lead nitrate.
(iv) Sodium sulphate from sodium carbonate.
Ans : - (i) Fe + H2SO4 (dil) → FeSO4 + H2
(ii) Cu + 2H2SO2 (conc.) → CuSO4 + H2O + SO2
(iii) Pb(NO3)2 + H2SO2 (dil.) → PbSO2 + 2HNO3
(iv) Na2CO3+ H2SO4 → Na2SO4 + H2O + CO2.
Q.5. Choosing the correct words given in brackets, complete the sentences given below:
(i) An acid is a compound which when dissolved in water gives ________
(hydronium/hydroxide) ions as the only ________ (positive/negative) ions.
(ii) An _________ (acid/basic) salt is one in which the hydrogen of an acid has
been partially replaced by a _________ (metal/non-metal).
Ans : - (i) hydronium, positive. (ii) acid, metal.
Q.6. Which of the following methods, A, B, C, D, or E is generally used for preparing the chlorides
listed below from (i) to (v). Answer by writing down the chloride and the letter pertaining to the
corresponding method. Each letter is to be used only once.
A. Action of an acid on a metal.
B. Action of an acid on oxide or carbonate.
C. Direct combination.
D. Neutralization of an alkali by an acid.
E. Precipitation (double decomposition).
(i) Copper (II) chloride.
(ii) Iron (II) chloride.
(iii) Iron (III) chloride.
(iv) Lead (II) chloride.
(v) Sodium chloride.
Ans : - (i) Copper (II) chloride – B.
(ii) Iron (II) chloride – A.
(iii) Iron (III) chloride – C.
(iv) Lead (II) chloride – E.
(v) Sodium chloride – D.
Q. 7. Fill in the blanks with suitable words:
An acid is a compound which when dissolved in water form Hydronium ions as the only (i)
___________ ions. A base is a compound which if soluble in water contains (ii) ____________
ions. A base reacts with an acid to form a (iii) _________ and water only. This type of reaction is
known as (iv) _________ .
Ans.: - (i) positive (ii) hydroxide (iii) salt (iv) neutralization.
Q. 8. The preparation of Lead sulphate from Lead carbonate is a two-step process. (Laed sulphate
cannot be prepared by adding dilute Sulphuric acid to Lead carbonate.)
(i) What is the first step that is required to prepare Lead sulphate from Lead carbonate ?
(ii) Write the equation for the reaction that will take place when this first step is carried out. (iii)
Why is the direct addition of dilute sulphuric acid to Lead carbonate an impractical method of
preparing Lead sulphate?
Ans.: - (i) The first step is to convert insoluble lead carbonate into soluble lead nitrate by
treating lead carbonate with dilute nitric acid.
(ii) PbCO3 (s) + 2HNO3(dil) → Pb(NO3)2 (aq) + H2O (l) + CO2 ↑
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(iii) When dilute sulphuric acid is added directly to lead carbonate, the lead
sulphate thus formed will be deposited on solid lead carbonate disconnecting
lead carbonate from sulphuric acid.
Q. 9. (i) Which feature of the Ammonia molecule leads to the formation of the
Ammonium ion when Ammonia dissolves in water?
(ii) Name the other ion formed when Ammonia dissolves in water.
(iii) Give one test that can be used to detect the presence of the ion produced
in(ii).
Ans.: - (i) Basic nature.
(ii) Hydroxide ion.
(iii) If an aqueous solution Fe2+ ions is added to a solution containing hydroxide
ions, a dirty green precipitate is formed.
Q. 10. Match the descriptions below with the appropriate term from the list A to F: A: Acidic oxide, B: Alkali, C: Amphoteric oxide, D: Basic oxide,
E: Deliquescence, F: Efflorescence.
(i) The property of spontaneously giving up water of crystallization to the
atmosphere. (ii) A compound, soluble in water and the only negative ions in the
solution are hydroxide ions.
Ans : - (i) F (ii) B.
Q.11. What is observed when, neutral litmus solution is added to sodium hydrogen
carbonate solution.
Ans.: - Colour of litmus solution is changed to blue.
Q. 12. Acids dissolve in water to produce positively charged ions. Draw the structure
of these ions.
Ans.: H+
!
:O: H
!
H
Q. 13. Mention the colour changes observed when the following indicators are added
to acids :(i) Alkaline phenolphthalein solution.
(ii) Methyl orange solution.
(iii) Neutral litmus solution.
Ans : - (i) From pink to colourless.
(ii) From pale yellow to pink.
(iii) Neutral litmus solution changes to red colour.
Q.14. Which of the following hydroxides is not an alkali :–
(a) ammonium hydroxide (b) calcium hydroxide
(c) copper hydroxide (d) sodium hydroxide.
Ans : - (c) copper hydroxide.
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Q.15. From the list given below, select the word(s) required to correctly complete blanks (i) to (v)
in the following passage :ammonia, ammonium, carbonate, carbon dioxide, hydrogen, hydronium, hydroxide, precipitate,
salt, water.
A solution X turns blue litmus red, so it must contain (i) ---------- ions; another solution Y turns red
litmus blue and therefore, must contain (ii) ------------- ions. When solution X and Y are mixed
together, the products will be a (iii) ------------- and (iv) ------------- . If a piece of magnesium were put
into solution X, (v) -------------- gas would be evolved.
Ans.: - (i) hydronium (ii) hydroxide (iii) salt (iv) water (v) hydrogen.
Q.16. Match the following :Column A
Column B
1. Acid salt
A. Sodium potassium
carbonate
2. Mixed salt
B. Alum
3. Complex salt
C. Sodium carbonate
4. Double salt
D. Sodium zincate
5. Normal salt
E. Sodium hydrogen carbonate
Ans :- 1. (E), 2. (A), 3. (D), 4. (B), 5. (C).