Learn Spanish (Latin America): El representante con quien conversaste es un experto. - The representative with whom you chatted is an expert.

In Spanish, when a relative pronoun referring to a person follows a preposition (like con, de, or a), you generally must use quien (singular) or quienes (plural). You cannot use just que after a preposition when referring to a person.

In English, I would normally say 'The representative you chatted with.' Can I put the con at the end of the sentence in Spanish?

No, Spanish never allows you to leave a preposition at the end of a sentence. The preposition must always come immediately before the relative pronoun. That is why it has to be con quien (with whom).

Could I use el que instead of quien here?

Yes! You can also say con el que or con el cual. All of these are grammatically correct, but con quien is very common and sounds slightly more elegant when talking about people.

What is the difference between using conversaste and hablaste?

They are very similar and often interchangeable. Hablar is the general word for to speak or to talk, while conversar specifically means to converse or to have a conversation. Using conversar emphasizes that there was a back-and-forth discussion.