Potash alum is a colourless inorganic compound typically made of potassium, aluminium, and sulphates in 1:1:2. Its chemical formula is K2SO4.Al2(SO4)3.24 H2O. It has a wide range of applications. It is used as a coagulant, water cleaner, antiseptic and in the textile and pharmaceutical industries.
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Definition: Potash alum, commonly known as fitkari, is a double salt containing potassium and aluminium. It is used as an antiseptic agent. |
Potash Alum Chemistry Questions with Solutions
Q1. What is the chemical formula of the potash alum?
(a) K2SO4.Al2(SO4)3.24 H2O
(b) KHSO4.Al2(SO4)3.24 H2O
(c) K2SO4.Al2(SO4)3.21 H2O
(d) None of the above
Answer: (a) K2SO4.Al2(SO4)3.24 H2O
Q2. What is the common name of the potash alum?
(a) Alum
(b) Fitkari
(c) Both (a) and (b)
(d) None of the above
Answer: (c) Both (a) and (b)
Q3. What is the colour of the potash alum?
(a) White
(b) Colourless
(c) Off-white
(d) None of the above
Answer: (b) Colourless
Q4. What is the shape of the crystal of the potash alum?
(a) Dihedral
(b) Octahedral
(c) Tetrahedral
(d) None of the above
Answer: (b) Octahedral
Q5. What is the IUPAC name of the potash alum?
(a) Aluminium potassium sulphate dodecahydrate
(b) Alumio potassium sulphate dodecahydrate
(c) Potassium aluminium sulphite dodecahydrate
(d) Potassium alumino sulphite dodecahydrate
Answer: (a) Aluminium potassium sulphate dodecahydrate
Q6. Why is the potash alum known as double salt?
Answer: Potash alum is known as double salt because it has two cations (potassium and aluminium). Its chemical formula is K2SO4.Al2(SO4)3.24 H2O.
Q7. Which acid is used in the preparation of the potash alum?
Answer: Diluted sulfuric acid is used to prepare potash alum to inhibit the hydrolysis of aluminium sulphate. It helps in dissolving aluminium sulphate in warm water.
Q8. What is the potassium, aluminium and sulphate ratio in the potash alum?
Answer: The chemical formula of potash alum is K2SO4.Al2(SO4)3.24 H2O.
The total number of potassium cations = 2.
The total number of aluminium cations = 2.
The total number of sulphate anions = 4.
The ratio of potassium, aluminium, and sulphate = 2:2:4.
The ratio of potassium, aluminium, and sulphate = 1:1:2
Q9. Write the reaction involved in the preparation of the potash alum.
Answer: Al2(SO4)3 (aq) + K2SO4 (aq) → K2SO4.Al2(SO4)3.24 H2O (s)
Q10. What are the properties of potash alum?
Answer: Potash alum is a double salt containing potassium and aluminium. The few properties of potash alum are mentioned below.
1. It is colourless.
2. It is soluble in water.
3. It is acidic and turns blue litmus red.
4. Its crystal is octahedral in shape.
Q11. What are the applications of potash alum?
Answer: Potash alum, commonly known as fitkari, has wide applications.
1. It is used in tanning leather.
2. It is used in the coagulation and flocculation of water during water treatment.
3. It is used to reduce teeth gum inflammation.
4. It is used in the textile industry as a drying agent.
5. It is used as an antiseptic agent.
6. It is used for dyeing wool.
Q12. What is the shape of a potash alum?
Answer: The crystal of potash alum is octahedral in shape.
Q13. Is alum edible?
Answer: Yes, we can consume potash alum. It is an active ingredient of baking powder.
Q14. What will happen if alum is added to sludgy water?
Answer: Alum will react with the bicarbonate alkalinities impurities in the sludgy water and form thick sediment.
Q15. Is alum an antiseptic?
Answer: Yes, alum is an antiseptic. It is used in cosmetic industries to manufacture deodorants.
Practise Questions on Potash Alum
Q1. What happens when potash alum is heated?
Q2. How is potash alum used to clean water?
Q3. Why is alum used after shaving?
Q4. What happens when alum is rubbed on blood?
Q5. Give any three characteristics of the potash alum.
Click the PDF to check the answers for Practice Questions.
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