Acids, Bases and Salts
अम्ल, क्षारक एवं लवण
Class 10 CBSE Science – Chapter 2
Board + Foundation + Competitive Level
Salts – लवण
1. What are Salts? | लवण क्या हैं?
A salt is generally an ionic compound formed when the hydrogen ion
of an acid is replaced by a metal ion or another positive ion.
लवण सामान्यतः एक आयनिक यौगिक है, जो अम्ल के हाइड्रोजन आयन के स्थान पर धातु आयन या किसी अन्य धनायन के आने से बनता है।
लवण सामान्यतः एक आयनिक यौगिक है, जो अम्ल के हाइड्रोजन आयन के स्थान पर धातु आयन या किसी अन्य धनायन के आने से बनता है।
HCl + NaOH → NaCl + H₂O
Here NaCl is the salt.
यहाँ NaCl लवण है।
2. Formation of Salts | लवण का निर्माण
Salts can be formed through several reactions:
- Acid + Base → Salt + Water
- Acid + Metal → Salt + Hydrogen
- Acid + Metal Carbonate → Salt + CO₂ + Water
- Acid + Metal Hydrogen Carbonate → Salt + CO₂ + Water
- Acid + Metal Oxide → Salt + Water
HCl + NaOH → NaCl + H₂O
2HCl + Zn → ZnCl₂ + H₂
2HCl + Na₂CO₃ → 2NaCl + CO₂ + H₂O
HCl + NaHCO₃ → NaCl + CO₂ + H₂O
2HCl + CuO → CuCl₂ + H₂O
3. Types of Salts | लवणों के प्रकार
Neutral Salt:
A salt formed by complete neutralisation.
Example: NaCl
Acidic Salt: Contains replaceable hydrogen and may be formed by partial neutralisation of a polybasic acid.
Example: NaHSO₄
Basic Salt: Contains basic hydroxyl groups or is formed due to incomplete neutralisation of a base.
Example: NaCl
Acidic Salt: Contains replaceable hydrogen and may be formed by partial neutralisation of a polybasic acid.
Example: NaHSO₄
Basic Salt: Contains basic hydroxyl groups or is formed due to incomplete neutralisation of a base.
4. pH of Salt Solutions | लवण विलयन का pH
| Salt | Nature | Approx. pH behaviour |
|---|---|---|
| NaCl | Neutral | ≈ 7 |
| CH₃COONa | Basic | > 7 |
| NH₄Cl | Acidic | < 7 |
5. Important Reactions
Na₂CO₃ + 2HCl → 2NaCl + CO₂ + H₂O
NaHCO₃ + HCl → NaCl + CO₂ + H₂O
AgNO₃ + NaCl → AgCl↓ + NaNO₃
Exam Point:
A salt does not necessarily have a neutral pH.
The nature of a salt solution depends on the acid and base from which
the salt is formed.
लवण का विलयन हमेशा उदासीन नहीं होता।
लवण का विलयन हमेशा उदासीन नहीं होता।
30 MCQ – Salts
30 Questions – 1 to 6 Marks
1 Mark
Q1. Define a salt.
A salt is an ionic compound generally formed by replacement of H⁺ of
an acid by a positive ion.
लवण: अम्ल के H⁺ के स्थान पर धनायन आने से बनने वाला आयनिक यौगिक लवण कहलाता है।
लवण: अम्ल के H⁺ के स्थान पर धनायन आने से बनने वाला आयनिक यौगिक लवण कहलाता है।
1 Mark
Q2. Give one example of a salt.
Answer: NaCl – Sodium chloride.
1 Mark
Q3. Which gas is produced when an acid reacts with a carbonate?
Answer: Carbon dioxide (CO₂).
1 Mark
Q4. Write the formula of common salt.
NaCl
1 Mark
Q5. Name the white precipitate formed when NaCl reacts with AgNO₃.
AgCl – Silver chloride.
2 Marks
Q6. Write two methods of salt formation.
1. Acid + Base → Salt + Water
2. Acid + Metal Carbonate → Salt + CO₂ + Water
2. Acid + Metal Carbonate → Salt + CO₂ + Water
2 Marks
Q7. Write the reaction between HCl and NaOH.
HCl + NaOH → NaCl + H₂O
This is a neutralisation reaction.
This is a neutralisation reaction.
2 Marks
Q8. What happens when sodium carbonate reacts with hydrochloric acid?
2HCl + Na₂CO₃ → 2NaCl + CO₂ + H₂O
Carbon dioxide gas is evolved.
Carbon dioxide gas is evolved.
2 Marks
Q9. Why are salts called ionic compounds?
They contain oppositely charged ions held together by electrostatic
forces.
2 Marks
Q10. Is every salt solution neutral?
No. Salt solutions may be acidic, basic or neutral depending on the
parent acid and base.
3 Marks
Q11. Explain three reactions by which salts are formed.
Acid + Base → Salt + Water
HCl + NaOH → NaCl + H₂O
Acid + Metal → Salt + H₂
2HCl + Zn → ZnCl₂ + H₂
Acid + Carbonate → Salt + CO₂ + H₂O
HCl + NaOH → NaCl + H₂O
Acid + Metal → Salt + H₂
2HCl + Zn → ZnCl₂ + H₂
Acid + Carbonate → Salt + CO₂ + H₂O
3 Marks
Q12. Explain acidic, basic and neutral salts.
Neutral salt: NaCl.
Acidic salt: NaHSO₄.
Basic salt: salts containing basic character or formed by suitable partial neutralisation.
Acidic salt: NaHSO₄.
Basic salt: salts containing basic character or formed by suitable partial neutralisation.
3 Marks
Q13. Write the reaction of sodium bicarbonate with HCl.
NaHCO₃ + HCl → NaCl + CO₂ + H₂O
The brisk effervescence is due to CO₂.
The brisk effervescence is due to CO₂.
3 Marks
Q14. Why does AgCl form a precipitate?
When AgNO₃ reacts with NaCl, insoluble AgCl is formed:
AgNO₃ + NaCl → AgCl↓ + NaNO₃
Therefore AgCl separates as a precipitate.
AgNO₃ + NaCl → AgCl↓ + NaNO₃
Therefore AgCl separates as a precipitate.
3 Marks
Q15. Explain the pH nature of NaCl, NH₄Cl and CH₃COONa solutions.
NaCl → approximately neutral.
NH₄Cl → acidic.
CH₃COONa → basic.
The difference arises from the acid-base strengths of their parent compounds.
NH₄Cl → acidic.
CH₃COONa → basic.
The difference arises from the acid-base strengths of their parent compounds.
4 Marks
Q16. Explain salt formation with four chemical equations.
HCl + NaOH → NaCl + H₂O
2HCl + Zn → ZnCl₂ + H₂
2HCl + Na₂CO₃ → 2NaCl + CO₂ + H₂O
2HCl + CuO → CuCl₂ + H₂O
2HCl + Zn → ZnCl₂ + H₂
2HCl + Na₂CO₃ → 2NaCl + CO₂ + H₂O
2HCl + CuO → CuCl₂ + H₂O
4 Marks
Q17. Explain why salt solutions can have different pH.
Salt solutions undergo interaction with water depending upon the ions
present.
Strong acid + strong base salt → generally neutral.
Weak acid + strong base salt → generally basic.
Strong acid + weak base salt → generally acidic.
Strong acid + strong base salt → generally neutral.
Weak acid + strong base salt → generally basic.
Strong acid + weak base salt → generally acidic.
4 Marks
Q18. Explain the reaction between sodium carbonate and HCl.
2HCl + Na₂CO₃ → 2NaCl + CO₂ + H₂O
Products are sodium chloride, carbon dioxide and water.
CO₂ can be identified by turning lime water milky.
Products are sodium chloride, carbon dioxide and water.
CO₂ can be identified by turning lime water milky.
4 Marks
Q19. Explain precipitation reaction using NaCl and AgNO₃.
AgNO₃ + NaCl → AgCl↓ + NaNO₃
AgCl is insoluble and forms a white precipitate. This is a precipitation reaction.
AgCl is insoluble and forms a white precipitate. This is a precipitation reaction.
4 Marks
Q20. Differentiate between neutral, acidic and basic salts.
Neutral salt → approximately neutral solution; example NaCl.
Acidic salt → acidic character; example NH₄Cl solution.
Basic salt → basic character; example CH₃COONa solution.
Acidic salt → acidic character; example NH₄Cl solution.
Basic salt → basic character; example CH₃COONa solution.
5 Marks
Q21. Explain the formation, properties and examples of salts.
Salts are ionic compounds.
They can be formed by neutralisation, acid-metal reaction, acid-carbonate reaction and acid-metal oxide reaction.
Examples: NaCl, KNO₃, CuSO₄.
Their solutions may be acidic, basic or neutral.
They can be formed by neutralisation, acid-metal reaction, acid-carbonate reaction and acid-metal oxide reaction.
Examples: NaCl, KNO₃, CuSO₄.
Their solutions may be acidic, basic or neutral.
5 Marks
Q22. Explain five important reactions involved in salt formation.
HCl + NaOH → NaCl + H₂O
2HCl + Zn → ZnCl₂ + H₂
2HCl + Na₂CO₃ → 2NaCl + CO₂ + H₂O
HCl + NaHCO₃ → NaCl + CO₂ + H₂O
2HCl + CuO → CuCl₂ + H₂O
2HCl + Zn → ZnCl₂ + H₂
2HCl + Na₂CO₃ → 2NaCl + CO₂ + H₂O
HCl + NaHCO₃ → NaCl + CO₂ + H₂O
2HCl + CuO → CuCl₂ + H₂O
5 Marks
Q23. Explain how the nature of salt solution depends upon its parent acid and base.
Strong acid + strong base → generally neutral salt solution.
Weak acid + strong base → generally basic salt solution.
Strong acid + weak base → generally acidic salt solution.
Thus the nature of ions determines the solution behaviour.
Weak acid + strong base → generally basic salt solution.
Strong acid + weak base → generally acidic salt solution.
Thus the nature of ions determines the solution behaviour.
5 Marks
Q24. Explain the importance of salts in daily life.
Salts are used in food preservation, baking, medicines, agriculture,
water treatment and several industrial processes.
NaCl is used as common salt. NaHCO₃ is used in baking. Na₂CO₃·10H₂O is washing soda.
NaCl is used as common salt. NaHCO₃ is used in baking. Na₂CO₃·10H₂O is washing soda.
5 Marks
Q25. Explain precipitation reaction with a suitable example.
A precipitation reaction produces an insoluble solid from aqueous
solutions.
AgNO₃ + NaCl → AgCl↓ + NaNO₃
AgCl is the insoluble white precipitate.
AgNO₃ + NaCl → AgCl↓ + NaNO₃
AgCl is the insoluble white precipitate.
6 Marks
Q26. Describe salts in detail with their classification and formation.
Salts are ionic compounds formed by reactions involving acids and bases.
Formation:
Acid + Base → Salt + Water
Acid + Metal → Salt + H₂
Acid + Carbonate → Salt + CO₂ + H₂O
Acid + Metal oxide → Salt + Water
Classification:
Neutral salts, acidic salts and basic salts.
Examples include NaCl, NaHSO₄ and CH₃COONa.
Formation:
Acid + Base → Salt + Water
Acid + Metal → Salt + H₂
Acid + Carbonate → Salt + CO₂ + H₂O
Acid + Metal oxide → Salt + Water
Classification:
Neutral salts, acidic salts and basic salts.
Examples include NaCl, NaHSO₄ and CH₃COONa.
6 Marks
Q27. Explain the chemical reactions of acids that lead to formation of salts.
Acid + Base:
HCl + NaOH → NaCl + H₂O
Acid + Metal:
2HCl + Zn → ZnCl₂ + H₂
Acid + Carbonate:
2HCl + Na₂CO₃ → 2NaCl + CO₂ + H₂O
Acid + Hydrogen carbonate:
HCl + NaHCO₃ → NaCl + CO₂ + H₂O
Acid + Metal oxide:
2HCl + CuO → CuCl₂ + H₂O
HCl + NaOH → NaCl + H₂O
Acid + Metal:
2HCl + Zn → ZnCl₂ + H₂
Acid + Carbonate:
2HCl + Na₂CO₃ → 2NaCl + CO₂ + H₂O
Acid + Hydrogen carbonate:
HCl + NaHCO₃ → NaCl + CO₂ + H₂O
Acid + Metal oxide:
2HCl + CuO → CuCl₂ + H₂O
6 Marks
Q28. Explain why all salts do not give neutral solutions.
The ions present in salts can react with water.
NaCl is formed from strong acid HCl and strong base NaOH, so its solution is approximately neutral.
NH₄Cl is formed from strong acid HCl and weak base NH₄OH, so its solution is acidic.
CH₃COONa is formed from weak acid CH₃COOH and strong base NaOH, so its solution is basic.
NaCl is formed from strong acid HCl and strong base NaOH, so its solution is approximately neutral.
NH₄Cl is formed from strong acid HCl and weak base NH₄OH, so its solution is acidic.
CH₃COONa is formed from weak acid CH₃COOH and strong base NaOH, so its solution is basic.
6 Marks
Q29. Solve and explain: 5.85 g NaCl is dissolved in water.
Calculate the number of moles of NaCl. (Na = 23, Cl = 35.5)
Molar mass of NaCl:
= 23 + 35.5
= 58.5 g mol⁻¹
Moles = Given mass / Molar mass
= 5.85 / 58.5
= 0.1 mol
Answer: 0.1 mol NaCl.
= 23 + 35.5
= 58.5 g mol⁻¹
Moles = Given mass / Molar mass
= 5.85 / 58.5
= 0.1 mol
Answer: 0.1 mol NaCl.
6 Marks
Q30. Explain the complete importance of salts with suitable examples.
Salts are important ionic compounds with wide applications.
NaCl → common salt and raw material for several chemicals.
NaHCO₃ → baking soda.
Na₂CO₃·10H₂O → washing soda.
CaSO₄·½H₂O → plaster of Paris.
They are important in food, medicine, construction, agriculture and industry.
NaCl → common salt and raw material for several chemicals.
NaHCO₃ → baking soda.
Na₂CO₃·10H₂O → washing soda.
CaSO₄·½H₂O → plaster of Paris.
They are important in food, medicine, construction, agriculture and industry.
Family of Salts – लवणों का परिवार
1. Meaning of Family of Salts
Salts having a common positive ion or a common negative ion are said
to belong to the same family of salts.
जिन लवणों में समान धनायन या समान ऋणायन होता है, वे एक ही family of salts से संबंधित माने जाते हैं।
जिन लवणों में समान धनायन या समान ऋणायन होता है, वे एक ही family of salts से संबंधित माने जाते हैं।
2. Family Based on Common Ions
Chloride family:
NaCl, KCl, CaCl₂
All contain Cl⁻ ion.
Sulphate family: Na₂SO₄, K₂SO₄, CuSO₄
All contain SO₄²⁻ ion.
Nitrate family: NaNO₃, KNO₃, AgNO₃
All contain NO₃⁻ ion.
All contain Cl⁻ ion.
Sulphate family: Na₂SO₄, K₂SO₄, CuSO₄
All contain SO₄²⁻ ion.
Nitrate family: NaNO₃, KNO₃, AgNO₃
All contain NO₃⁻ ion.
3. Important Examples
| Family | Examples | Common ion |
|---|---|---|
| Chlorides | NaCl, KCl, CaCl₂ | Cl⁻ |
| Sulphates | Na₂SO₄, CuSO₄, K₂SO₄ | SO₄²⁻ |
| Nitrates | NaNO₃, KNO₃, AgNO₃ | NO₃⁻ |
| Carbonates | Na₂CO₃, CaCO₃, K₂CO₃ | CO₃²⁻ |
30 MCQ – Family of Salts
Q1. Salts with a common ion form a:
A. Family of salts
B. Element family
C. Metal family only
D. Gas family
Answer: A
Q2. NaCl and KCl belong to which family?
A. Chloride
B. Sulphate
C. Nitrate
D. Carbonate
Answer: A
Q3. Common ion in Na₂SO₄ and CuSO₄ is:
A. Na⁺
B. Cu²⁺
C. SO₄²⁻
D. Cl⁻
Answer: C
Q4. NaNO₃ and KNO₃ belong to:
A. Nitrate family
B. Chloride family
C. Sulphate family
D. Carbonate family
Answer: A
Q5. Common ion in carbonates is:
A. CO₃²⁻
B. SO₄²⁻
C. NO₃⁻
D. Cl⁻
Answer: A
Q6. CaCl₂ belongs to:
A. Chloride family
B. Sulphate family
C. Nitrate family
D. Carbonate family
Answer: A
Q7. Which is a sulphate?
A. CuSO₄
B. NaCl
C. KNO₃
D. Na₂CO₃
Answer: A
Q8. Which is a nitrate?
A. AgNO₃
B. AgCl
C. Ag₂CO₃
D. Ag₂SO₄
Answer: A
Q9. Which pair has a common Cl⁻ ion?
A. NaCl and KCl
B. Na₂SO₄ and K₂SO₄
C. KNO₃ and NaNO₃
D. Na₂CO₃ and CaCO₃
Answer: A
Q10. Common ion of nitrate family is:
A. NO₃⁻
B. Cl⁻
C. SO₄²⁻
D. CO₃²⁻
Answer: A
Q11. Which pair belongs to sulphate family?
A. Na₂SO₄ and CuSO₄
B. NaCl and KCl
C. KNO₃ and AgNO₃
D. Na₂CO₃ and CaCO₃
Answer: A
Q12. A family is identified mainly by:
A. Common ion
B. Colour only
C. Mass only
D. Shape only
Answer: A
Q13. Which contains SO₄²⁻?
A. K₂SO₄
B. KCl
C. KNO₃
D. K₂CO₃
Answer: A
Q14. Which contains CO₃²⁻?
A. CaCO₃
B. CaCl₂
C. CaSO₄
D. Ca(NO₃)₂
Answer: A
Q15. NaCl and NaNO₃ have:
A. Same Na⁺ ion
B. Same anion
C. Same formula
D. Same molecular mass
Answer: A
Q16. KCl and KNO₃ have:
A. Same K⁺ ion
B. Same anion
C. Same formula
D. Same colour
Answer: A
Q17. Which family contains AgNO₃?
A. Nitrate
B. Chloride
C. Carbonate
D. Sulphate
Answer: A
Q18. Which family contains CaCO₃?
A. Carbonate
B. Nitrate
C. Chloride
D. Sulphate
Answer: A
Q19. Which pair has common NO₃⁻?
A. NaNO₃ and AgNO₃
B. NaCl and AgCl
C. Na₂SO₄ and CuSO₄
D. Na₂CO₃ and CaCO₃
Answer: A
Q20. Common ion in chloride salts is:
A. Cl⁻
B. SO₄²⁻
C. NO₃⁻
D. CO₃²⁻
Answer: A
Q21. Which is NOT a chloride?
A. Na₂SO₄
B. NaCl
C. KCl
D. CaCl₂
Answer: A
Q22. Which is NOT a nitrate?
A. KCl
B. KNO₃
C. NaNO₃
D. AgNO₃
Answer: A
Q23. Family of salts is based upon:
A. Common ion
B. Density only
C. Colour only
D. Melting point only
Answer: A
Q24. Which two have common Na⁺?
A. NaCl and Na₂SO₄
B. KCl and KNO₃
C. CaCO₃ and CaCl₂
D. CuSO₄ and CuCl₂
Answer: A
Q25. Na₂CO₃ belongs to:
A. Carbonate family
B. Chloride family
C. Nitrate family
D. Sulphate family
Answer: A
Q26. Which pair belongs to same family?
A. NaCl and KCl
B. NaCl and KNO₃
C. Na₂SO₄ and KNO₃
D. CaCO₃ and KCl
Answer: A
Q27. SO₄²⁻ is called:
A. Sulphate ion
B. Sulphide ion
C. Nitrate ion
D. Chloride ion
Answer: A
Q28. NO₃⁻ is called:
A. Nitrate ion
B. Nitrite ion
C. Sulphate ion
D. Carbonate ion
Answer: A
Q29. CO₃²⁻ is:
A. Carbonate ion
B. Chloride ion
C. Nitrate ion
D. Sulphate ion
Answer: A
Q30. Which statement is correct?
A. Salts with a common ion can form a family
B. Every salt has the same ion
C. Every salt is NaCl
D. Salts cannot contain polyatomic ions
Answer: A
30 Questions – 1 to 6 Marks
1 Mark
Q1. What is meant by family of salts?
Salts having a common ion are said to belong to the same family.
1 Mark
Q2. Name the common ion in NaCl and KCl.
Cl⁻
1 Mark
Q3. Name the common ion in Na₂SO₄ and CuSO₄.
SO₄²⁻
1 Mark
Q4. Give one nitrate salt.
KNO₃
1 Mark
Q5. Give one carbonate salt.
CaCO₃
2 Marks
Q6. Explain chloride family with two examples.
NaCl, KCl and CaCl₂ contain Cl⁻ ion and therefore belong to chloride
family.
2 Marks
Q7. Explain sulphate family.
Na₂SO₄, K₂SO₄ and CuSO₄ contain SO₄²⁻ ion and belong to sulphate family.
2 Marks
Q8. What is common in NaNO₃ and KNO₃?
Both contain NO₃⁻ ion and belong to nitrate family.
2 Marks
Q9. Can two salts have same cation but different anions?
Yes. NaCl and NaNO₃ both contain Na⁺ but have different anions.
2 Marks
Q10. Can two salts have same anion but different cations?
Yes. NaCl and KCl have the same Cl⁻ ion but different cations.
3 Marks
Q11. Explain three families of salts with examples.
Chlorides: NaCl, KCl.
Sulphates: Na₂SO₄, CuSO₄.
Nitrates: NaNO₃, KNO₃.
Sulphates: Na₂SO₄, CuSO₄.
Nitrates: NaNO₃, KNO₃.
3 Marks
Q12. Identify the family of Na₂CO₃, CaCO₃ and K₂CO₃.
All contain CO₃²⁻, so they belong to carbonate family.
3 Marks
Q13. Differentiate cation family and anion family with examples.
NaCl and NaNO₃ share Na⁺.
NaCl and KCl share Cl⁻.
Thus common cations or anions can be used to group salts.
NaCl and KCl share Cl⁻.
Thus common cations or anions can be used to group salts.
3 Marks
Q14. Identify common ions in the following pairs: NaCl/KCl and Na₂SO₄/CuSO₄.
NaCl/KCl → Cl⁻.
Na₂SO₄/CuSO₄ → SO₄²⁻.
Na₂SO₄/CuSO₄ → SO₄²⁻.
3 Marks
Q15. Why is grouping salts into families useful?
It helps identify salts by common ions and makes their chemical
properties and reactions easier to study and compare.
4 Marks
Q16. Explain chloride, sulphate, nitrate and carbonate families.
Chloride → Cl⁻ → NaCl, KCl.
Sulphate → SO₄²⁻ → Na₂SO₄, CuSO₄.
Nitrate → NO₃⁻ → NaNO₃, KNO₃.
Carbonate → CO₃²⁻ → Na₂CO₃, CaCO₃.
Sulphate → SO₄²⁻ → Na₂SO₄, CuSO₄.
Nitrate → NO₃⁻ → NaNO₃, KNO₃.
Carbonate → CO₃²⁻ → Na₂CO₃, CaCO₃.
4 Marks
Q17. Explain common cation and common anion with examples.
Common cation:
NaCl and NaNO₃ share Na⁺.
Common anion:
NaCl and KCl share Cl⁻.
NaCl and NaNO₃ share Na⁺.
Common anion:
NaCl and KCl share Cl⁻.
4 Marks
Q18. Classify the following: NaCl, KNO₃, CuSO₄, CaCO₃.
NaCl → Chloride.
KNO₃ → Nitrate.
CuSO₄ → Sulphate.
CaCO₃ → Carbonate.
KNO₃ → Nitrate.
CuSO₄ → Sulphate.
CaCO₃ → Carbonate.
4 Marks
Q19. What is a polyatomic ion? Give two examples found in salt families.
A charged group of two or more covalently bonded atoms acting as one
ion is called a polyatomic ion.
Examples: SO₄²⁻ and NO₃⁻.
Examples: SO₄²⁻ and NO₃⁻.
4 Marks
Q20. Explain the importance of common ions in identifying salts.
A common ion provides a basis for grouping salts.
For example, all salts containing Cl⁻ can be placed in chloride family.
This helps in systematic study of salts and their reactions.
5 Marks
Q21. Explain family of salts in detail with examples.
A family of salts consists of salts sharing a common ion.
Chloride: NaCl, KCl, CaCl₂.
Sulphate: Na₂SO₄, K₂SO₄, CuSO₄.
Nitrate: NaNO₃, KNO₃, AgNO₃.
Carbonate: Na₂CO₃, CaCO₃, K₂CO₃.
The common ion determines the family.
Chloride: NaCl, KCl, CaCl₂.
Sulphate: Na₂SO₄, K₂SO₄, CuSO₄.
Nitrate: NaNO₃, KNO₃, AgNO₃.
Carbonate: Na₂CO₃, CaCO₃, K₂CO₃.
The common ion determines the family.
5 Marks
Q22. Explain how salts can have same cation or same anion.
Same cation:
NaCl and NaNO₃ → Na⁺ common.
Same anion: NaCl and KCl → Cl⁻ common.
Thus salts may be grouped based on either common cation or common anion.
Same anion: NaCl and KCl → Cl⁻ common.
Thus salts may be grouped based on either common cation or common anion.
5 Marks
Q23. Classify ten salts into suitable families.
Chlorides: NaCl, KCl, CaCl₂.
Sulphates: Na₂SO₄, CuSO₄, K₂SO₄.
Nitrates: KNO₃, NaNO₃.
Carbonates: Na₂CO₃, CaCO₃.
Sulphates: Na₂SO₄, CuSO₄, K₂SO₄.
Nitrates: KNO₃, NaNO₃.
Carbonates: Na₂CO₃, CaCO₃.
5 Marks
Q24. Explain the role of ions in classification of salts.
Salts dissociate into ions in aqueous solution.
The common ions allow salts to be grouped into families.
For example, Cl⁻ gives chloride family and SO₄²⁻ gives sulphate family.
5 Marks
Q25. Explain nitrate and carbonate families with formulae.
Nitrate ion = NO₃⁻.
Examples: NaNO₃, KNO₃, AgNO₃.
Carbonate ion = CO₃²⁻. Examples: Na₂CO₃, CaCO₃, K₂CO₃.
Carbonate ion = CO₃²⁻. Examples: Na₂CO₃, CaCO₃, K₂CO₃.
6 Marks
Q26. Describe the major families of salts in detail.
Chlorides → Cl⁻ → NaCl, KCl, CaCl₂.
Sulphates → SO₄²⁻ → Na₂SO₄, K₂SO₄, CuSO₄.
Nitrates → NO₃⁻ → NaNO₃, KNO₃, AgNO₃.
Carbonates → CO₃²⁻ → Na₂CO₃, CaCO₃, K₂CO₃.
Grouping is based on common ions.
Sulphates → SO₄²⁻ → Na₂SO₄, K₂SO₄, CuSO₄.
Nitrates → NO₃⁻ → NaNO₃, KNO₃, AgNO₃.
Carbonates → CO₃²⁻ → Na₂CO₃, CaCO₃, K₂CO₃.
Grouping is based on common ions.
6 Marks
Q27. Explain how common cations and anions can be used to form salt families.
NaCl and NaNO₃ have common Na⁺.
NaCl and KCl have common Cl⁻.
Na₂SO₄ and CuSO₄ have common SO₄²⁻.
NaNO₃ and KNO₃ have common NO₃⁻.
Thus either common positive or negative ions can be used to compare and group salts.
NaCl and KCl have common Cl⁻.
Na₂SO₄ and CuSO₄ have common SO₄²⁻.
NaNO₃ and KNO₃ have common NO₃⁻.
Thus either common positive or negative ions can be used to compare and group salts.
6 Marks
Q28. Explain the importance of family classification for chemical analysis.
Family classification makes it easier to identify common ions,
predict related reactions and systematically study large numbers of
salts.
For example, chloride salts can be tested for Cl⁻ using suitable chemical reactions.
For example, chloride salts can be tested for Cl⁻ using suitable chemical reactions.
6 Marks
Q29. Identify the families of NaCl, K₂SO₄, AgNO₃ and CaCO₃ and justify.
NaCl → Cl⁻ → Chloride.
K₂SO₄ → SO₄²⁻ → Sulphate.
AgNO₃ → NO₃⁻ → Nitrate.
CaCO₃ → CO₃²⁻ → Carbonate.
Each classification is based on its characteristic common anion.
K₂SO₄ → SO₄²⁻ → Sulphate.
AgNO₃ → NO₃⁻ → Nitrate.
CaCO₃ → CO₃²⁻ → Carbonate.
Each classification is based on its characteristic common anion.
6 Marks
Q30. Explain family of salts with examples of common cations and anions.
Salts can be grouped according to common ions.
Common cation example: NaCl and NaNO₃ → Na⁺.
Common anion example: NaCl and KCl → Cl⁻.
Anion families include chloride, sulphate, nitrate and carbonate. This classification simplifies the study of salts.
Common cation example: NaCl and NaNO₃ → Na⁺.
Common anion example: NaCl and KCl → Cl⁻.
Anion families include chloride, sulphate, nitrate and carbonate. This classification simplifies the study of salts.
Common Salt — Sodium Chloride
1. What is Common Salt?
Common salt is sodium chloride, NaCl.
It is one of the most important salts used in everyday life and
industry.
साधारण नमक का रासायनिक सूत्र NaCl है।
साधारण नमक का रासायनिक सूत्र NaCl है।
2. Sources of Common Salt
Common salt is obtained mainly from:
- Sea water
- Rock salt deposits
- Salt lakes and brine
3. Preparation from Sea Water
Sea water contains dissolved sodium chloride along with several other
salts.
Water is removed by evaporation and salt is obtained.
4. Electrolysis of Brine
Concentrated aqueous solution of sodium chloride is called brine.
Electrolysis of brine produces sodium hydroxide, chlorine and hydrogen.
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
5. Important Uses of NaCl
- Food seasoning
- Food preservation
- Raw material for chemicals
- Production of NaOH
- Production of chlorine
- Production of hydrogen
- Production of baking soda and washing soda indirectly
6. Rock Salt
Rock salt is naturally occurring sodium chloride found in underground
deposits.
It may contain impurities and is mined from the earth.
30 MCQ – Common Salt
Q1. Chemical formula of common salt is:
A. NaCl
B. NaOH
C. HCl
D. KCl
Answer: A
Q2. Common salt is:
A. Sodium chloride
B. Sodium hydroxide
C. Calcium chloride
D. Potassium nitrate
Answer: A
Q3. Concentrated aqueous NaCl solution is called:
A. Brine
B. Lime water
C. Milk of lime
D. Bleach
Answer: A
Q4. Electrolysis of brine produces:
A. NaOH, Cl₂ and H₂
B. NaCl and O₂
C. HCl and O₂
D. Na₂CO₃ only
Answer: A
Q5. The process involving electrolysis of brine is called:
A. Chlor-alkali process
B. Haber process
C. Contact process
D. Solvay process
Answer: A
Q6. One product of chlor-alkali process is:
A. NaOH
B. H₂SO₄
C. CaCO₃
D. NH₃
Answer: A
Q7. Gas released at anode during brine electrolysis is:
A. Chlorine
B. Hydrogen
C. Oxygen
D. Nitrogen
Answer: A
Q8. Gas released at cathode is:
A. Hydrogen
B. Chlorine
C. Oxygen
D. Carbon dioxide
Answer: A
Q9. NaCl is obtained from sea water mainly by:
A. Evaporation
B. Filtration only
C. Sublimation
D. Distillation only
Answer: A
Q10. Naturally occurring impure NaCl is called:
A. Rock salt
B. Baking soda
C. Washing soda
D. Bleaching powder
Answer: A
Q11. NaCl is important industrially because it is:
A. Raw material for several chemicals
B. Only a food colour
C. An acid
D. A metal
Answer: A
Q12. NaCl contains:
A. Na⁺ and Cl⁻
B. Na²⁺ and Cl²⁻
C. H⁺ and OH⁻
D. K⁺ and Cl⁻
Answer: A
Q13. Brine is:
A. Concentrated aqueous NaCl
B. Solid NaOH
C. Pure HCl
D. Dry NaCl
Answer: A
Q14. Which chemical is produced directly in chlor-alkali process?
A. Sodium hydroxide
B. Sodium carbonate
C. Calcium carbonate
D. Ammonium chloride
Answer: A
Q15. Common salt is mainly used in food as:
A. Seasoning
B. Fuel
C. Catalyst only
D. Indicator
Answer: A
Q16. Rock salt is found in:
A. Underground deposits
B. Clouds
C. Pure air
D. Metals only
Answer: A
Q17. Sodium chloride is a:
A. Salt
B. Base
C. Acid
D. Element
Answer: A
Q18. Which gas is useful for manufacture of HCl?
A. H₂
B. N₂
C. O₂
D. CO₂
Answer: A
Q19. Which product is a strong base?
A. NaOH
B. Cl₂
C. H₂
D. NaCl
Answer: A
Q20. Which product is a halogen gas?
A. Cl₂
B. H₂
C. NaOH
D. NaCl
Answer: A
Q21. NaCl is present abundantly in:
A. Sea water
B. Pure distilled water
C. Oxygen gas
D. Nitrogen gas
Answer: A
Q22. Electrolysis requires:
A. Electric current
B. Sunlight only
C. Pressure only
D. Freezing
Answer: A
Q23. Chlorine is obtained at:
A. Anode
B. Cathode
C. Salt bridge
D. Filter
Answer: A
Q24. Hydrogen is obtained at:
A. Cathode
B. Anode
C. Both always
D. Neither
Answer: A
Q25. The chlor-alkali process uses:
A. Brine
B. Pure ethanol
C. Dry nitrogen
D. Sulphur
Answer: A
Q26. Which is NOT a product of brine electrolysis?
A. NaOH
B. Cl₂
C. H₂
D. Na₂SO₄
Answer: D
Q27. Formula of sodium chloride is:
A. NaCl
B. Na₂Cl
C. NaCl₂
D. Na₂Cl₂
Answer: A
Q28. Common salt is used as a raw material for:
A. Chlor-alkali process
B. Photosynthesis
C. Respiration only
D. Rusting
Answer: A
Q29. The equation 2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂ represents:
A. Chlor-alkali process
B. Neutralisation
C. Combustion
D. Precipitation
Answer: A
Q30. Which statement is correct?
A. NaCl has major industrial importance
B. NaCl is an acid
C. NaCl is a metal
D. NaCl cannot dissolve in water
Answer: A
30 Questions – 1 to 6 Marks
1 Mark
Q1. What is the chemical formula of common salt?
NaCl.
1 Mark
Q2. What is brine?
A concentrated aqueous solution of sodium chloride.
1 Mark
Q3. Name the process used to manufacture NaOH from brine.
Chlor-alkali process.
1 Mark
Q4. Name the gas produced at anode during brine electrolysis.
Chlorine (Cl₂).
1 Mark
Q5. Name the gas produced at cathode.
Hydrogen (H₂).
2 Marks
Q6. Name two sources of common salt.
Sea water and rock salt deposits.
2 Marks
Q7. Write two uses of common salt.
Food seasoning and food preservation.
2 Marks
Q8. What is rock salt?
Naturally occurring sodium chloride found in underground deposits,
usually containing impurities.
2 Marks
Q9. Write the equation of chlor-alkali process.
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
2 Marks
Q10. Why is the process called chlor-alkali?
Because chlorine (chlor) and sodium hydroxide (an alkali) are produced.
3 Marks
Q11. Explain preparation of common salt from sea water.
Sea water contains dissolved NaCl.
Water is removed by evaporation, leaving salt behind.
Further purification may be carried out depending on intended use.
3 Marks
Q12. Explain brine electrolysis.
Concentrated NaCl solution is electrolysed.
NaOH forms in solution, chlorine is liberated at anode and hydrogen
at cathode.
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
3 Marks
Q13. State three products of chlor-alkali process.
1. Sodium hydroxide.
2. Chlorine.
3. Hydrogen.
2. Chlorine.
3. Hydrogen.
3 Marks
Q14. Explain two uses of sodium chloride.
NaCl is used as a food seasoning and preservative.
It is also an important industrial raw material.
3 Marks
Q15. Explain the importance of rock salt.
Rock salt is a natural source of NaCl and is obtained from underground
deposits through mining.
4 Marks
Q16. Explain the chlor-alkali process with equation.
Brine is electrolysed using electricity.
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
NaOH is formed in solution, Cl₂ at anode and H₂ at cathode.
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
NaOH is formed in solution, Cl₂ at anode and H₂ at cathode.
4 Marks
Q17. Explain the industrial importance of common salt.
NaCl is used in food and preservation.
More importantly, it is used as a raw material for NaOH, chlorine,
hydrogen and several other chemicals.
4 Marks
Q18. Explain the products obtained from brine.
Sodium hydroxide remains in solution.
Chlorine is liberated at the anode.
Hydrogen is liberated at the cathode.
Overall: 2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
Overall: 2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
4 Marks
Q19. Explain the difference between sea salt and rock salt.
Sea salt is obtained mainly by evaporation of sea water.
Rock salt is mined from underground deposits.
Both are sources of sodium chloride, though rock salt can contain
more mineral impurities.
4 Marks
Q20. Why is NaCl called an important industrial raw material?
Because it is used to manufacture NaOH, chlorine and hydrogen through
the chlor-alkali process and is also involved in preparation of other
important chemicals.
5 Marks
Q21. Explain common salt from source to industrial use.
Common salt is NaCl.
It is obtained from sea water, brine and rock salt deposits.
It is purified and used as food seasoning and preservative.
Industrially, concentrated NaCl solution is electrolysed to produce
NaOH, Cl₂ and H₂.
5 Marks
Q22. Explain chlor-alkali process in detail.
Brine is concentrated aqueous NaCl.
During electrolysis, chloride ions are oxidised at the anode to form
Cl₂, while water is reduced at the cathode to form H₂ and OH⁻.
Na⁺ combines with OH⁻ to form NaOH.
Overall: 2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
Overall: 2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
5 Marks
Q23. Describe three products of chlor-alkali process and their uses.
NaOH: soaps, detergents, paper and chemical industries.
Cl₂: water treatment, bleaching and chemical manufacture.
H₂: fuel and manufacture of chemicals.
Cl₂: water treatment, bleaching and chemical manufacture.
H₂: fuel and manufacture of chemicals.
5 Marks
Q24. Explain how common salt connects household chemistry with industrial chemistry.
At home NaCl is used for seasoning and preservation.
In industry it serves as raw material for producing NaOH, chlorine
and hydrogen through electrolysis of brine.
Thus the same compound has both domestic and industrial importance.
5 Marks
Q25. Explain sources and uses of sodium chloride.
Sources:
1. Sea water.
2. Rock salt.
3. Natural brine.
Uses:
Food seasoning, preservation and industrial manufacture of important chemicals.
1. Sea water.
2. Rock salt.
3. Natural brine.
Uses:
Food seasoning, preservation and industrial manufacture of important chemicals.
6 Marks
Q26. Describe common salt and chlor-alkali process comprehensively.
Common salt is NaCl and is obtained from sea water and rock salt.
A concentrated NaCl solution is called brine.
Electrolysis:
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
NaOH forms in solution, chlorine at anode and hydrogen at cathode. The process is called chlor-alkali process. It has major industrial importance.
Electrolysis:
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
NaOH forms in solution, chlorine at anode and hydrogen at cathode. The process is called chlor-alkali process. It has major industrial importance.
6 Marks
Q27. Explain the electrochemical reactions in chlor-alkali process.
At anode:
2Cl⁻ → Cl₂ + 2e⁻
At cathode:
2H₂O + 2e⁻ → H₂ + 2OH⁻
In solution:
Na⁺ + OH⁻ → NaOH
Overall:
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
2Cl⁻ → Cl₂ + 2e⁻
At cathode:
2H₂O + 2e⁻ → H₂ + 2OH⁻
In solution:
Na⁺ + OH⁻ → NaOH
Overall:
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
6 Marks
Q28. Explain the importance of common salt in everyday life and industry.
Domestic uses include seasoning and preservation of food.
Industrial uses include production of NaOH, chlorine and hydrogen. These chemicals are used in soaps, paper, bleaching, water treatment and many other industries.
Industrial uses include production of NaOH, chlorine and hydrogen. These chemicals are used in soaps, paper, bleaching, water treatment and many other industries.
6 Marks
Q29. 11.7 g NaCl is dissolved in water. Calculate moles of NaCl.
(Na = 23, Cl = 35.5)
Molar mass NaCl = 23 + 35.5 = 58.5 g mol⁻¹.
Moles = 11.7 / 58.5
= 0.2 mol.
Answer: 0.2 mol NaCl.
Moles = 11.7 / 58.5
= 0.2 mol.
Answer: 0.2 mol NaCl.
6 Marks
Q30. Explain why brine is preferred instead of solid NaCl in chlor-alkali process.
Electrolysis requires mobile ions.
In aqueous brine, Na⁺ and Cl⁻ ions are free to move and conduct
electricity.
Therefore electrolysis can occur efficiently.
Solid NaCl does not provide freely mobile ions in the same way.
Chemicals from Common Salt – साधारण नमक से रसायन
1. Chlor-Alkali Process
Electrolysis of brine produces three important chemicals:
Sodium hydroxide (NaOH)
Chlorine (Cl₂)
Hydrogen (H₂)
Sodium hydroxide (NaOH)
Chlorine (Cl₂)
Hydrogen (H₂)
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
2. Sodium Hydroxide
NaOH is a strong alkali.
Uses include:
- Soap and detergent manufacture
- Paper industry
- Artificial textile fibres
- Aluminium extraction
- Various chemical processes
3. Chlorine
Chlorine is a greenish-yellow toxic gas with a characteristic
odour.
Uses:
- Disinfection of drinking water
- Manufacture of bleaching agents
- PVC and other chemicals
- Preparation of hydrochloric acid
4. Hydrogen
Hydrogen is a combustible gas.
It is used as a fuel and in chemical manufacturing.
5. Baking Soda
Baking soda is sodium hydrogen carbonate:
NaHCO₃
It can be prepared industrially using sodium chloride as one of the starting materials.
NaHCO₃
It can be prepared industrially using sodium chloride as one of the starting materials.
NaCl + CO₂ + H₂O + NH₃ → NH₄Cl + NaHCO₃
6. Washing Soda
Washing soda is sodium carbonate decahydrate:
Na₂CO₃·10H₂O
It is obtained from sodium hydrogen carbonate by heating and subsequent crystallisation.
Na₂CO₃·10H₂O
It is obtained from sodium hydrogen carbonate by heating and subsequent crystallisation.
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
7. Important Chain
NaCl → NaOH + Cl₂ + H₂
NaCl → NaHCO₃ → Na₂CO₃·10H₂O
30 MCQ – Chemicals from Common Salt
Q1. Which chemical is obtained directly from brine electrolysis?
A. NaOH
B. Na₂CO₃·10H₂O
C. CaCO₃
D. CaSO₄
Answer: A
Q2. Which gas is produced at anode?
A. Cl₂
B. H₂
C. CO₂
D. O₂
Answer: A
Q3. Which gas is produced at cathode?
A. H₂
B. Cl₂
C. CO₂
D. N₂
Answer: A
Q4. NaOH is:
A. Strong alkali
B. Weak acid
C. Salt only
D. Neutral gas
Answer: A
Q5. Formula of baking soda is:
A. NaHCO₃
B. Na₂CO₃
C. NaCl
D. NaOH
Answer: A
Q6. Formula of washing soda is:
A. Na₂CO₃·10H₂O
B. NaHCO₃
C. NaCl
D. CaCO₃
Answer: A
Q7. Baking soda is:
A. Sodium hydrogen carbonate
B. Sodium chloride
C. Sodium hydroxide
D. Sodium sulphate
Answer: A
Q8. Washing soda is:
A. Sodium carbonate decahydrate
B. Sodium bicarbonate
C. Sodium chloride
D. Sodium hydroxide
Answer: A
Q9. Heating NaHCO₃ produces:
A. Na₂CO₃
B. NaCl
C. NaOH
D. HCl
Answer: A
Q10. The gas evolved on heating NaHCO₃ is:
A. CO₂
B. H₂
C. Cl₂
D. N₂
Answer: A
Q11. NaHCO₃ is used in:
A. Baking
B. Making steel only
C. Fuel only
D. Mining only
Answer: A
Q12. Which is a product of chlor-alkali process?
A. Chlorine
B. CaCO₃
C. NH₃
D. H₂SO₄
Answer: A
Q13. Which product is used for water disinfection?
A. Chlorine
B. NaHCO₃
C. NaCl
D. Na₂CO₃
Answer: A
Q14. NaOH is used in manufacture of:
A. Soap
B. Oxygen
C. Nitrogen
D. Sand
Answer: A
Q15. Washing soda contains:
A. 10 molecules of water of crystallisation
B. No water
C. 2 molecules only
D. 1 molecule only
Answer: A
Q16. Which reaction produces sodium carbonate?
A. 2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
B. NaCl → NaOH
C. HCl → NaCl
D. NaOH → NaCl
Answer: A
Q17. Which is an alkali?
A. NaOH
B. NaCl
C. HCl
D. CO₂
Answer: A
Q18. Which is used in baking powder formulations?
A. NaHCO₃
B. NaCl only
C. HCl
D. Cl₂
Answer: A
Q19. Na₂CO₃·10H₂O is:
A. Washing soda
B. Baking soda
C. Common salt
D. Bleaching powder
Answer: A
Q20. Which compound is used in glass and soap industries?
A. Washing soda
B. HCl only
C. H₂
D. Cl₂ only
Answer: A
Q21. Which substance releases CO₂ on heating?
A. NaHCO₃
B. NaCl
C. NaOH
D. KCl
Answer: A
Q22. Which chemical can be produced from NaCl through brine electrolysis?
A. NaOH
B. Na₂CO₃ directly by electrolysis
C. CaCO₃
D. CaSO₄
Answer: A
Q23. Which process uses brine?
A. Chlor-alkali process
B. Photosynthesis
C. Fermentation
D. Respiration
Answer: A
Q24. Which product of chlor-alkali process is combustible?
A. H₂
B. Cl₂
C. NaOH
D. NaCl
Answer: A
Q25. Which product is a toxic gas?
A. Cl₂
B. NaOH
C. NaCl
D. Na₂CO₃
Answer: A
Q26. Which substance is used in soap manufacture?
A. NaOH
B. H₂
C. CO₂
D. Cl₂ only
Answer: A
Q27. Which is obtained from common salt indirectly?
A. Baking soda
B. Oxygen
C. Nitrogen
D. Sulphur
Answer: A
Q28. The starting material in Solvay process is:
A. Brine / NaCl solution
B. Pure oxygen
C. Sulphuric acid only
D. Hydrogen only
Answer: A
Q29. What is the common name of NaHCO₃?
A. Baking soda
B. Washing soda
C. Common salt
D. Bleaching powder
Answer: A
Q30. What is the common name of Na₂CO₃·10H₂O?
A. Washing soda
B. Baking soda
C. Common salt
D. Caustic soda
Answer: A
30 Questions – 1 to 6 Marks
1 Mark
Q1. Name the three products of chlor-alkali process.
NaOH, Cl₂ and H₂.
1 Mark
Q2. Give the formula of baking soda.
NaHCO₃.
1 Mark
Q3. Give the formula of washing soda.
Na₂CO₃·10H₂O.
1 Mark
Q4. Name the gas evolved on heating NaHCO₃.
CO₂.
1 Mark
Q5. What is NaOH commonly called?
Caustic soda.
2 Marks
Q6. Write two uses of NaOH.
Soap manufacture and paper industry.
2 Marks
Q7. Write two uses of chlorine.
Water disinfection and manufacture of bleaching chemicals.
2 Marks
Q8. What is baking soda?
Sodium hydrogen carbonate, NaHCO₃, commonly called baking soda.
2 Marks
Q9. What is washing soda?
Sodium carbonate decahydrate, Na₂CO₃·10H₂O.
2 Marks
Q10. Write the thermal decomposition reaction of NaHCO₃.
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
3 Marks
Q11. Explain three products of chlor-alkali process.
NaOH is an alkali.
Cl₂ is a useful industrial gas.
H₂ is a combustible gas.
Cl₂ is a useful industrial gas.
H₂ is a combustible gas.
3 Marks
Q12. Explain baking soda and its formula.
Baking soda is sodium hydrogen carbonate.
Formula: NaHCO₃.
It is used in baking and releases CO₂ under suitable conditions.
Formula: NaHCO₃.
It is used in baking and releases CO₂ under suitable conditions.
3 Marks
Q13. Explain washing soda formation.
On heating NaHCO₃:
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
Na₂CO₃ can then crystallise with water to form Na₂CO₃·10H₂O.
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
Na₂CO₃ can then crystallise with water to form Na₂CO₃·10H₂O.
3 Marks
Q14. Why is chlorine important?
It is used in water disinfection, bleaching and manufacture of several
important chemicals including chlorinated polymers.
3 Marks
Q15. Why is NaOH called an alkali?
NaOH is a base that is soluble in water and produces OH⁻ ions.
Therefore it is classified as an alkali.
4 Marks
Q16. Explain chlor-alkali process and its products.
Brine is electrolysed:
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
NaOH, Cl₂ and H₂ are the three major products.
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
NaOH, Cl₂ and H₂ are the three major products.
4 Marks
Q17. Explain baking soda preparation from common salt.
In the Solvay process, brine is treated with ammonia and carbon dioxide
under suitable conditions to precipitate sodium hydrogen carbonate.
NaCl + CO₂ + H₂O + NH₃ → NaHCO₃ + NH₄Cl
NaCl + CO₂ + H₂O + NH₃ → NaHCO₃ + NH₄Cl
4 Marks
Q18. Explain the conversion of baking soda into washing soda.
Heating baking soda gives sodium carbonate:
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
Crystallisation with water produces Na₂CO₃·10H₂O.
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
Crystallisation with water produces Na₂CO₃·10H₂O.
4 Marks
Q19. Give four uses of chemicals obtained from common salt.
NaOH → soap manufacture.
Cl₂ → water disinfection.
H₂ → fuel/chemical manufacture.
Na₂CO₃ → glass, soap and detergent industries.
Cl₂ → water disinfection.
H₂ → fuel/chemical manufacture.
Na₂CO₃ → glass, soap and detergent industries.
4 Marks
Q20. Explain the chemical chain from NaCl to washing soda.
NaCl is used as a starting material in the Solvay process.
NaCl → NaHCO₃ → Na₂CO₃ → Na₂CO₃·10H₂O
Thus common salt contributes to production of washing soda.
NaCl → NaHCO₃ → Na₂CO₃ → Na₂CO₃·10H₂O
Thus common salt contributes to production of washing soda.
5 Marks
Q21. Explain the manufacture and uses of sodium hydroxide.
Sodium hydroxide is manufactured by electrolysis of brine:
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
Uses include soap, paper, detergents, textile fibres and several chemical processes.
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
Uses include soap, paper, detergents, textile fibres and several chemical processes.
5 Marks
Q22. Explain baking soda: preparation, reaction and uses.
Baking soda = NaHCO₃.
Preparation:
NaCl + CO₂ + H₂O + NH₃ → NaHCO₃ + NH₄Cl
On heating:
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
It is used in baking and some household applications.
Preparation:
NaCl + CO₂ + H₂O + NH₃ → NaHCO₃ + NH₄Cl
On heating:
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
It is used in baking and some household applications.
5 Marks
Q23. Explain washing soda: formula, formation and uses.
Formula: Na₂CO₃·10H₂O.
It is obtained by crystallisation of sodium carbonate with water.
Uses include glass, soap and detergent industries and water softening.
It is obtained by crystallisation of sodium carbonate with water.
Uses include glass, soap and detergent industries and water softening.
5 Marks
Q24. Explain the industrial importance of chlorine.
Chlorine is obtained from brine.
It is used for disinfection of drinking water, manufacture of
bleaching chemicals, HCl and chlorinated compounds such as PVC.
5 Marks
Q25. Explain the relationship between common salt, baking soda and washing soda.
Common salt provides the NaCl starting material.
NaCl can be used to obtain NaHCO₃.
NaHCO₃ on heating gives Na₂CO₃.
Na₂CO₃ crystallises with water to form washing soda:
Na₂CO₃·10H₂O.
NaCl can be used to obtain NaHCO₃.
NaHCO₃ on heating gives Na₂CO₃.
Na₂CO₃ crystallises with water to form washing soda:
Na₂CO₃·10H₂O.
6 Marks
Q26. Explain all major chemicals obtained from common salt.
Through chlor-alkali process:
NaCl → NaOH + Cl₂ + H₂
Through Solvay-related chemistry:
NaCl → NaHCO₃ → Na₂CO₃ → Na₂CO₃·10H₂O
Thus common salt is an important raw material for several industrial chemicals.
NaCl → NaOH + Cl₂ + H₂
Through Solvay-related chemistry:
NaCl → NaHCO₃ → Na₂CO₃ → Na₂CO₃·10H₂O
Thus common salt is an important raw material for several industrial chemicals.
6 Marks
Q27. Explain the chlor-alkali process with electrode reactions.
At anode:
2Cl⁻ → Cl₂ + 2e⁻
At cathode:
2H₂O + 2e⁻ → H₂ + 2OH⁻
Na⁺ combines with OH⁻ to form NaOH.
Overall:
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
2Cl⁻ → Cl₂ + 2e⁻
At cathode:
2H₂O + 2e⁻ → H₂ + 2OH⁻
Na⁺ combines with OH⁻ to form NaOH.
Overall:
2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
6 Marks
Q28. Explain the Solvay process concept related to common salt.
Brine is saturated with ammonia and treated with carbon dioxide.
Sodium hydrogen carbonate precipitates because of its limited
solubility:
NaCl + NH₃ + CO₂ + H₂O → NaHCO₃ + NH₄Cl
NaHCO₃ is heated:
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
The sodium carbonate can then be crystallised to give washing soda.
NaCl + NH₃ + CO₂ + H₂O → NaHCO₃ + NH₄Cl
NaHCO₃ is heated:
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
The sodium carbonate can then be crystallised to give washing soda.
6 Marks
Q29. Explain the complete reaction chain from NaCl to Na₂CO₃·10H₂O.
Step 1:
NaCl + NH₃ + CO₂ + H₂O → NaHCO₃ + NH₄Cl
Step 2:
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
Step 3:
Na₂CO₃ + 10H₂O → Na₂CO₃·10H₂O
The final product is washing soda.
NaCl + NH₃ + CO₂ + H₂O → NaHCO₃ + NH₄Cl
Step 2:
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
Step 3:
Na₂CO₃ + 10H₂O → Na₂CO₃·10H₂O
The final product is washing soda.
6 Marks
Q30. A student says “common salt is only useful for cooking.” Explain why this statement is incorrect.
The statement is incorrect because NaCl is a major industrial raw
material.
It is used to manufacture:
1. NaOH
2. Cl₂
3. H₂
4. NaHCO₃
5. Na₂CO₃
6. Na₂CO₃·10H₂O
Therefore common salt has extensive domestic as well as industrial importance.
It is used to manufacture:
1. NaOH
2. Cl₂
3. H₂
4. NaHCO₃
5. Na₂CO₃
6. Na₂CO₃·10H₂O
Therefore common salt has extensive domestic as well as industrial importance.
