Question

08. Write the chemical reactions of following statement:
i) Decomposition of zinc carbonate
ii) Passing carbon di oxide gas into the lime water.
iii) Aluminum oxide reacts with hydrochloric acid.​

Answer 1

Answer:-

i) Decomposition of zinc carbonate.

Decomposition reaction: The reaction in which a compound splits or decomposes in two or more elements or compounds is called Chemical decomposition reaction.

Chemical equation :

ZnCO₃ ⟶ ZnO + CO₂

ii) Passing Carbon dioxide gas into lime water.

Lime water is nothing but Calcium hydroxide.

When calcium hydroxide reacts with carbon dioxide, a precipitate called calcium carbonate I'd formed along with water.

This is an example of Precipitation reaction (Double displacement reaction).

" A double displacement reaction in which two compounds react with each other to form a precipitate along with water is called Precipitation reaction".

Chemical equation :

Ca(OH)₂ + CO₂ ⟶ CaCO₃ (↓) + H₂O

iii) Aluminium oxide reacts with hydrochloric acid.

Aluminium oxide which is a base reacts with hydrochloric acid to form a salt called Aluminium chloride along with water.

"A double displacement reaction in which an acid and a base react with each other to form a salt and water is called Neutralisation reaction."

So, this is an example of neutralisation reaction.

Chemical equation :

Al₂O₃ + HCl ⟶ AlCl₃ + H₂O

Answer 2

Explanation:

i) Decomposition of zinc carbonate.

Chemical equation :

• ZnCO₃ ⟶ ZnO + CO₂

Zinc carbonate is a white powdery solid.

• When it is heated strongly, it starts to turn yellow and decompose - carbon dioxide gas is evolved, which forms a white precipitate in limewater.

• The yellow solid left behind in the test-tube is hot zinc oxide.

ii) Passing Carbon dioxide gas into lime water.

Chemical equation :

• Ca(OH)₂ + CO₂ ⟶ CaCO₃ (↓) + H₂O

Lime water is the solution of calcium hydroxide in water.

• When it is passed on with carbon dioxide gas, it turns the lime water milky due to the formation of a white precipitate of calcium carbonate.

iii) Aluminium oxide reacts with hydrochloric acid.

Chemical equation :

• Al₂O₃ + HCl ⟶ AlCl₃ + H₂O

Reaction with acids:

• Aluminum oxide contains oxide ions, and thus reacts with acids in the same way sodium or magnesium oxides do.

• Aluminum oxide reacts with hot dilute hydrochloric acid to give aluminum chloride solution.

• This reaction and others display the amphoteric nature of aluminum oxide.