What is the difference between preguntar and pedir?
I know these both mean "to ask" but would you use these in different circumstances or are they interchangeable?
They are not interchangeable.
Preguntar= to ask (as in a question)
Por ejemplo: preguntar algo a alguien = to ask somebody something (a question)
Pedir=to ask for (as in a request)
Por ejemplo: pedir algo a alguien = to ask somebody for something (a drink of water)
Here's a link to study the differences a bit more.
p.s I got these examples straight from SpanishDict's dictionary.