题目

Hotel Icaria Barcelona Hotel Location Hotel Icaria Barcelona is 330 yards from Barcelona’s Nova Icaria Beach. It is located in the Olympic Port area, a 10-minute walk from Ciutadella Park and Barcelona Zoo. Ciutadella Metro Station is half a mile away, and is just 2 stops from Barcelona Cathedral (大教堂) and the historic Gothic Quarter.Hotel Facilities GeneralRestaurant, 24-Hour Front Desk, Non-Smoking Rooms, Rooms / Facilities for Disabled Guests, Family Rooms, Luggage Storage, Smoking Area. ActivitiesSauna, Fitness Centre, Wellness Centre, Table Tennis, Hiking, Cycling, Steam Bath,15．某同学在实验室发现一瓶标签残缺（如图1所示）的硫酸镁溶液．为了测定此溶液的溶质质量分数，他取出25g该溶液，向其中逐滴加入溶质质量分数为10%的NaOH溶液．反应过程中生成沉淀的质量与所用NaOH溶液质量的关系如图2所示．请计算：（1）此溶液的溶质质量分数．（2）实验中所生成的沉淀的质量是多少克？