for - to 
(for purpose)

   
                1)    Purpose of things/objects
                        To explain the use of an object, we use for + ing :

                        ◊  What is this sponge for?
                            It is for cleaning the sink.

                 2)    Purpose of actions
                        To explain for what reason we do something, we use the infinitive
                        (e.g. to do) :

                        ◊ What do you use this sponge for?
                           I use it to clean the sink.

                        ◊ Why did you turn on the radio?
                          I turned on the radio to listen to the news