Something specific or a specific something ,which one to use? [duplicate]

Question

As in the title , I want to know which one of these sentences is correct and why?

I want to do something specific.
or
I want to do a specific something.   

Answer 1

Using "something" as a noun is informal, which is what you are doing when you say, "a something." As such, if this is for any formal communication, you would write, "something specific." Otherwise, either way is fine.