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Difficulty: MediumAlkenes and Alkynes: Preparation, Reactions, and Unsaturation Tests

In the laboratory preparation of ethyne gas, water is added dropwise to solid calcium carbide (CaC2CaC_2). What is the IUPAC name of the inorganic compound produced as a byproduct in this reaction?

Answer: Calcium hydroxide / calcium hydroxide / Ca(OH)2 / Ca(OH)₂

Answer

Calcium hydroxide
Hydrolysis of calcium carbide (CaC2CaC_2) produces ethyne (C2H2C_2H_2) as the desired hydrocarbon gas along with calcium hydroxide (Ca(OH)2Ca(OH)_2) as the inorganic byproduct.

Step-by-Step Solution

1
Write the balanced chemical equation for the hydrolysis of calcium carbide.
CaC2(s)+2H2O(l)→C2H2(g)+Ca(OH)2(s)CaC_2(s) + 2H_2O(l) \rightarrow C_2H_2(g) + Ca(OH)_2(s)
Calcium carbide reacts exothemically with water to liberate ethyne gas and leave behind a solid residue of calcium hydroxide.
2
Identify the chemical name of the inorganic byproduct Ca(OH)2Ca(OH)_2.
Calcium hydroxide
The inorganic salt contains calcium ions (Ca2+Ca^{2+}) and hydroxide ions (OH−OH^-), giving the IUPAC name calcium hydroxide.

Key Concept

Laboratory preparation of ethyne by hydrolysis of calcium carbide
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Topics

Alkenes and Alkynes: Preparation, Reactions, and Unsaturation Tests

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