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.
where is the electron transport chain located
The only membrane in prokaryotes is the cellular membrane, that is where the ETC is located.
where is the electron transport chain locatedin eukaryotes
In Eukaryotes it occurs in inner membrane of mitochondria while in prokaryotes it occurs in cell plasma membrane.

Question: why the difference
Self-contained rewrite: why is the location of the electron transport chain different in eukaryotes and prokaryotes?