There's the French expression -- which is used in English -- "raison d'être," which means something's reason for being, for existing at all. Example: Art is the artist's raison d'être. (Maybe that's too romantic a use for you.) A more common expression is "made for," as in "A shovel was made for digging." Or, "A woman was made to have babies." (LOL...a little dated humor, but still great.)

“Used to” sounds okay in all of those sentences. “Used for” also sounds good. But “used in” does not sound right to me. Also, in each of those examples, I would put the word “A” before your first word. “A hammer is used...” And “soups” sounds funny to me. You just need to say “soup” in the singular.

used to is legit: What algorithm is used to decide when ... Cream of tartar is used to increase ... ... which is used to treat a problem ... All citations are from the Corpus of Contemporary American English.