题干

雯雯在自学碳酸钠性质时,查到了以下资料:

①CO2+Na2CO3+H2O═2NaHCO3,CO2通入饱和碳酸钠溶液会产生白色沉淀,CO2不溶于饱和碳酸氢钠溶液.

②碳酸钠、碳酸氢钠在不同温度下的溶解度

0℃

10℃

20℃

30℃

Na2CO3

7.1

12.2

21.8

39.7

NaHCO3

6.9

8.1

9.6

11.1

【进行实验1】验证CO2通入饱和碳酸钠溶液会产生白色沉淀

①配制碳酸钠溶液:取100g 20℃的水,加入35g碳酸钠固体,搅拌后,静置,取上层清液.

②利用装置一进行实验,连续5分钟向新制得的碳酸钠溶液中通入CO2.

【发现问题】实验中,始终没有看到沉淀现象,原因是什么呢?雯雯进行了以下实验探究.

【进行实验2】

实验操作

实验现象

①取100g 20℃的水,加入35g碳酸钠固体,搅拌后,静置,取上层清液

②利用装置二进行实验,连续5分钟向新制得的碳酸钠溶液中通入CO2

没有出现白色沉淀

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       The evidence for harmony may not be obvious in some families. But it seems that four out of five young people now get on with their parents, which is the opposite of the popularly held image of unhappy teenagers locked in their room after endless family quarrels.
    An important new study into teenage attitudes (态度) surprisingly shows that their family life is happier than it has ever been in the past. “We were surprised by just how positive (积极的) today’s young people seem to be about their families,” said one member of the research team.     “They're expected to be rebellious(叛逆的)and selfish but actually they have other things on their minds; they want a car and material goods, and they worry about whether school is serving them well. There's discussion between parents and children, and children expect to take part in the family decision-making process. They don't want to rock the boat.”
          So it seems that these parents are much more likely than parents of 30 years ago to treat their children as friends. “My parents are happy to discuss things with me and willing to listen to me,” says 17-year-old Daniel LaSalle. “I always tell them when I'm going out clubbing. When they know what I'm doing, they're fine with it.” Susan Cromer, who is now 21, agrees. “Looking back on the last 10 years, there was a lot of what you could call talk or discussion. For example, when I'd done all my homework, I could go out on a Saturday night. But I think my grandparents were a lot stricter with my parents than that.”
        Maybe this positive view of family life should not be unexpected. It is possible that the idea of teenage rebellion(叛逆)is not based on real facts. A researcher explains, “Teenagers were thought to be different from others in a part of time in our social history. But to our surprise, they say they are getting on well with their parents. But that idea of rebelling and breaking away from their parents really only happened during that one time in the 1960s when everyone rebelled.”