小明同学将13.9g含杂质的纯碱样品（碳酸钠与氯化钠的混合物） 与90.5g稀盐酸相混合，充分反应，测得反应生成气体的质量（m）与反应时间（t）的数据如下表所示：

根据题目要求，回答下列问题：

（1）碳酸钠完全反应后，生成CO₂的质量　．

（2）求完全反应后所得溶液中溶质的质量分数．

阅读理解

                                                                                         Enjoying Dinner with Friends in America

        Americans, like many people else where in the world, like to invite friends to their homes for an evening of food, drink and conversation. Formal dinners, in fine homes and hotels in the United States are much the same as formal dinners anywhere in the world. But as most people in the United States have no servants (佣人) , their dinner parties at home are mostly informal. Guests may sit down at a table, or, as many new small homes have no separate (单独的) dining room or very small dining space, guests can also serve themselves and eat in the living room, holding their plates on their knees.

        A more enjoyable form of entertainment is the picnic. Americans are great picnickers, and almost every family has a picnic basket. Summer invitations are often for a picnic at a park or in the open countryside. Unless hamburgers or hot dogs are cooked over a fire, picnic food is usually cold sandwiches, salads, potato chips, etc. Watermelon is a favourite dessert, followed very often by baseball for the young and active, and naps (打盹) for the weary (疲惫的； 困乏的).

“一般不用K、Ca、Na等活泼金属来置换盐溶液中的其他金属元素”，这是教科书上的一句话。 小科对此进行了思考，并查阅资料，对金属钠和硫酸铜溶液的反应进行探究。

【查阅资料】钠常温下就能与水发生剧烈反应，反应方程式为:2Na+2H₂O==2NaOH +H₂↑。

【提出猜想】猜想一:金属钠和硫酸铜溶液反应会有铜生成。

猜想二:金属钠和硫酸铜溶液反应，生成的沉淀只有氢氧化铜。

【实验及现象】切取不同大小的钠块分别投入到两种不同浓度的硫酸铜溶液中，有关产生沉淀

的现象如下表所示。

小科咨询老师后得知蓝绿色沉淀为碱式铜盐。