Answer the questions below in relation to the following organic compounds: ethene (C2H4) and ethyne (C2H2) - Leaving Cert Chemistry - Question 1 - 2012

Solid Y is typically a dehydrating agent such as concentrated sulfuric acid (H2SO4) or alumina (Al2O3), which assists in the elimination reaction to produce ethene.

To prevent a 'suck-back', a one-way valve or a water trap can be implemented in the apparatus to allow gas to escape but not suck back liquid into the reaction vessel. A 'suck-back' can present the risk of causing liquid to be drawn back into the hot reaction vessel, leading to possible explosions or damage.

The type of organic reaction involved is dehydration, which is the removal of water from an alcohol to produce an alkene such as ethene.

In preparing ethyne (acetylene), the common laboratory method involves the reaction of calcium carbide (CaC2) with water (H2O). The reaction can be represented as:

CaC2 + 2 H2O → C2H2 + Ca(OH)2

A labelled diagram should include a reaction vessel with calcium carbide, a delivery tube leading to a water jar overflowing with water to collect the ethyne gas, and labels for each component.

Unsaturated compounds are those that contain at least one double or triple bond between carbon atoms, allowing them to react with additional atoms or molecules. Ethene (C2H4) contains a carbon-carbon double bond, while ethyne (C2H2) contains a carbon-carbon triple bond.

To test for unsaturation in ethene, you can use bromine water. Ethene will decolorize bromine water due to the addition reaction with the double bond, indicating that it is unsaturated.