Key fact An impure substance is a type of mixture, so melting points can be used to find out if a substance is pure or impure. Impure substances tend to have a slightly lower melting point than ...

Final one now, salt. Katie: Oh, salt. I feel like I want to say that's impure because salt must be a mix of different things. Miss Fong: No, salt is actually pure. Katie: Ah. Miss Fong ...