When water drops are added to calcium carbide in a container and the gas produced is passed through a jet and lighted, the resultant flame is called an?

1. Analyze the question

The question asks for the name of the flame produced when the gas generated from the reaction between calcium carbide ($CaC_2$) and water is ignited.

2. Explain the concept

• The Reaction: When water is added to calcium carbide, a chemical reaction occurs that produces ethyne (also known as acetylene) gas and calcium hydroxide. • Equation: $CaC_2(s) + 2H_2O(l) \rightarrow C_2H_2(g) + Ca(OH)_2(aq)$
• The Gas: The gas produced is $C_2H_2$, which is ethyne (acetylene).
• The Flame: When this gas is burned in the presence of oxygen (often through a specialized jet or torch), it produces an extremely hot flame. This specific type of flame is widely used in welding and cutting metals and is famously known as an oxyacetylene flame.

3. Show the solution

• Step 1: Identify the gas produced: $CaC_2 + 2H_2O \rightarrow C_2H_2 + Ca(OH)_2$. The gas is ethyne ($C_2H_2$).
• Step 2: Recognize the common name for ethyne: Ethyne is commonly referred to as acetylene.
• Step 3: Combine the gas name with the oxygen source: Burning acetylene in oxygen creates the "oxyacetylene" flame.
• Step 4: Compare with options: Option C matches this terminology perfectly.

4. Identify the answer

The correct option is C.

5. Exam Tip

In chemistry exams, remember that Ethyne = Acetylene. Whenever you see "calcium carbide" in a question, immediately associate it with the production of ethyne gas. Also, remember that the oxyacetylene flame is famous for its very high temperature, which is why it is the standard for industrial welding.