题目

    Rules for the University Entrance Examination •    You must be at the examination center ten minutes before the examination starts. If you are more than ten minutes late, you may not enter the examination center. The examination takes place at the same time in different states. •    You must have proof of your name and grade as well as official examination number. Show these when you come to the examination center. •    Depending on which examination you are taking, you may bring certain items into the examination center. Mathematics examinations may allow you to （1）向硫酸氢钠溶液中，逐滴加入Ba(OH)2溶液至中性。请写出发生反应的化学方程式：                         ；（2）在以上中性溶液中，继续滴加Ba(OH)2溶液，请写出此步反应的离子方程式                     ；