Recently I asked a similar question on Chinese SE: Why would Antimony (Sb) and Aluminum (Al) be confused?
It seems, though, that this is by no means a Chinese phenomenon.
The Wiki page for Tin foil mentions that:
aluminium foil, [...] is still referred to as "tinfoil" in many regions.
What other chemicals are often confused for different chemicals?
I'm especially interested in things that have retained their incorrect names.