Is a catalyst used to produce LDPE? If so, what is it called?
the molecule that is used is called an initiator it's different from a catalyst (substance that increases rate of reaction for a chemical reaction through providing an alternate pathway and is not actually consumed in the reaction, hence why we never write is a product or reactant, however rather on top of the arrow in a chemical equation).organic peroxide
Yep can confirm it is used up and a part of the final molecule as this forms:http://preparatorychemistry.com/images/Addition_polymer_steps.jpgYeah as Jazz said, I think it's called an initiator instead. The initiator is essentially an organic peroxide such as benzoyl peroxide.
Basically an initiator molecule 'splits' to form free radicals. These free radicals are highly reactive due to its unpaired electron and can react readily with the electron dense double bond of an ethylene monomer to form an initiator-ethylene radical. This is considered the first step of the LDPE production process called 'initiation'.
Just remember that catalysts speed up the reaction rate and aren't used up in the net reaction (like Jazz also said). The initiator benzoyl peroxide is different to a catalyst since it allows the polymerisation process to occur in the first place instead of speeding it up and are technically used in the reaction (since I think the initiator atoms ends up appearing at the ends of the polymer chain once LDPE formation is finished - I'm not fully sure of this though haha).