Question

15. Quick lime combines vigorously with water to form (A)
which reacts slowly with the carbon dioxide in air to
form (B).
What are (A) and (B)?
(B)
(a) Calcium carbonate Calcium hydroxide
(b) Calcium hydroxide Calcium carbonate
(c) Calcium
Calcium bicarbonate
(d) Calcium bicarbonate Calcium​

Answer 1

Answer:

Quick lime( CaO) combines vigorously with water to form Ca(OH)2 which is product A and Ca(OH)2 reacts with CO2 in air to form CaCO3 .

Explanation:

Part-1

• Quick lime combines vigorously with water to form calcium hydroxide .
• Reaction:

        CaO + H2O → Ca(OH)2

• It is an exothermic reaction.
• Exothermic Reaction: A reaction in which heat is generated as a product of reaction.

Part-2

• Calcium hydroxide reacts with calcium dioxide from air to form calcium carbonate.
• Reaction:

        Ca(OH)2 + CO2 → CaCO3 + H2O

• Calcium hydroxide reacts with carbon dioxide from the air to produce a solid calcium carbonate precipitate and water.
• This reaction is a double displacement reaction.
• It is also a neutralization reaction ,carbon dioxide is acidic in nature as acids and bases react to give salt and water.
• Neutralization is a chemical reaction in which acid and a base react to form salt and water .
• Double displacement reaction is a type of reaction where one reactant is replaced by part of another reactant.
• Double displacement reaction can explain as : AB + CD → AD + CB

Answer 2

Answer:

Quick lime combines vigorously with water to form calcium hydroxide which reacts slowly with the carbon dioxide in the air to form calcium carbonate.

Explanation:

• When calcium oxide(quick lime) reacts with water, the following reaction takes place: CaO + H₂O → Ca(OH)₂
• The product of this reaction is calcium hydroxide, also known as slaked lime.
• The reaction also releases a lot of heat. Thus, it is an exothermic reaction.
• This calcium hydroxide reacts with atmospheric carbon dioxide to form calcium carbonate and water.
• The reaction is Ca(OH)₂ + CO₂ → CaCO₃ + H₂O
• Overall, the reaction is a two-step process.

Therefore, The products (A) and (B) are (b) Calcium hydroxide Calcium carbonate.

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