write the acid-base reaction between KHP and water

1. in the standardization of NaOH with KHP titration what is the secondary standard?2. write the acid-base reaction between KHP and water showing the chemical structure of KHP. in other words show the proton transfer between KHP and water.3. why is it assumed that the reaction between NaOH and KHP goes to completion? would it be a source of error in the experiment if it did not? why or why not?