The vast majority of students of Spanish as a foreign language I’ve had the chance to meet has always asked one question. What’s the difference between POR and PARA?
Apart from asking them whether they have checked grammar books—or because I’m an asshole but because I want to know what they know already—I usually tell them that English has got one sentence that works wonders!
I bought this for you
FOR can be expanded to avoid different interpretations, as clearly the sentence can mean:
1. I bought this for you (You’ll receive it)
2. I bought this on your behalf.
3. I bought this because of you. (not quite the first idea you’d get when using FOR, but it’s still grammatically correct)
So, if you can use FOR and BECAUSE OF interchangeably, then the Spanish equivalent is POR. Note that in this case, you’re highlighting a reason; the motivation for your buying whatever you at have purchased. Further examples in Spanish are:
Lo hizo por gusto (He/She/It did it because he/she/it wanted to do it) .
Le sucedió por flojo (That happened to him/her because of his/her laziness).
Then, if you can replace FOR with ON SB’S BEHALF, then the Spanish equivalent is EN VEZ DE (QUE).
Finally, if you want to express who the receiver of something is, then you must use PARA. This Spanish preposition is used to convey other meanings; as a general rule, you must append it to infinitives when expressing objectives (this means that there’s no option to express TO GO/FOR GOING at prepositional level). Please remember that infinitives in Spanish end in ~AR, ~ER or ~IR and that if you were to say CANTANDO (singing), that means that someone is singing now.
There is yet another use of PARA. We use this preposition when we want to express the idea of somebody is good at + something/doing something and when somebody is prone to + something/doing something. Regretfully, context is the key to disambiguating these sentences:
Pedro es bueno para comer sandía –> Pedro is prone to eating watermelon.
Pedro es bueno para aprender idiomas –> Pedro is good at language learning.