The hydrogenation of ethyne acetylene to ethane using a palladium catalyst is a heterogeneous catalytic process that occurs through a series of steps. The mechanism can be described as follows:1. Adsorption: The ethyne molecule and hydrogen molecules adsorb onto the surface of the palladium catalyst. The palladium surface has a high affinity for both ethyne and hydrogen, which allows them to bind to the surface.2. Bond activation: The adsorbed hydrogen molecule dissociates into two hydrogen atoms on the palladium surface. Similarly, the triple bond in the ethyne molecule weakens due to the interaction with the catalyst surface.3. Hydrogen addition: One of the hydrogen atoms on the palladium surface reacts with one of the carbon atoms in the ethyne molecule, forming a C-H bond and converting the triple bond into a double bond. This intermediate species is called ethene ethylene .4. Second hydrogen addition: Another hydrogen atom on the palladium surface reacts with the other carbon atom in the ethene molecule, forming another C-H bond and converting the double bond into a single bond. This results in the formation of ethane.5. Desorption: The ethane molecule, now fully hydrogenated, desorbs from the palladium surface and leaves the catalyst, allowing new reactant molecules to adsorb and continue the reaction.Overall, the hydrogenation of ethyne to ethane using a palladium catalyst is a stepwise process that involves adsorption, bond activation, hydrogen addition, and desorption. The palladium catalyst plays a crucial role in activating the reactants and facilitating the hydrogenation process.