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