Expressing purpose with to and for

We can use to + infinitive and for + noun to say what is the purpose of an action, or the reason why we do something.
 

To + infinitive

 

For + noun

Compare to vs for:

 

For + -ing

Don’t use for + -ing to talk about why we do something

We don’t use for + -ing to say what is the purpose of our actions, why we do something.

Use for + -ing to talk about the purpose or function of an object

We use for + ing to talk about the purpose or function of a thing, what an object is used for.