Conversation so far:
where is the electron transport chain located in eukaryotes and prokaryotes
In eukaryotes the electron transport chain is situated in the mitochondiral membrane. Prokaryotes do not have organelles such as mitochondria, but they do have an ETC.
what is required for the electron transport chain to work
A membrane is required for the ETC to work, otherwise it would not be possible to build a gradient of hydrogen atoms.

Question: where is the chain located
Self-contained rewrite: where is the electron transport chain located