Due to the unstable nature of ethyne, it is stored by dissolving in

1. Analyze the question

The question asks for the specific solvent used to safely store ethyne (acetylene) gas. Ethyne is highly unstable and can explode if compressed or stored in its pure form under pressure.

2. Explain the concept

Ethyne ($C_2H_2$) is an alkyne that is highly reactive and thermally unstable. When subjected to high pressure, it can undergo explosive decomposition. To transport and store it safely, it is dissolved in a solvent that can hold large volumes of the gas without reacting with it.

The industry standard for this is propanone (also known as acetone). Propanone has a high capacity for dissolving ethyne; at a pressure of about 15 atmospheres, one volume of propanone can dissolve about 300 volumes of ethyne. The gas is usually stored in cylinders filled with a porous material (like diatomaceous earth) soaked in propanone.

3. Show the solution

• Step 1: Identify the chemical properties of ethyne. It is a highly flammable and unstable gas.
• Step 2: Evaluate the options provided: • Ethane-1,2-diol: Used as an antifreeze, not for gas storage. • Propanol: An alcohol, not the standard solvent for ethyne. • Ethanoic acid: A carboxylic acid that would react with many substances and is not suitable for this purpose. • Propanone (Acetone): A ketone that is chemically inert toward ethyne and has a very high solubility for the gas, making it the ideal medium for safe storage.
• Step 3: Conclude that propanone is the correct solvent used in industrial gas cylinders.

4. Identify the answer

The correct option is D.

5. Exam Tip

When you see questions about ethyne (acetylene) in your JAMB or WASSCE exams, always associate it with propanone (acetone). Also, remember that ethyne is produced by the reaction of calcium carbide ($CaC_2$) with water. These two facts are frequently tested together!