题干

实验室中有一瓶长期使用的氢氧化钠固体样品,某兴趣小组的同学对该样品的成分及含量进行探究.

发现问题】该样品中含有哪些物质?

【查阅资料】①NaOH在空气中不会转化成NaHCO3

②BaCl2溶液呈中性,Ba(OH)2是可溶性碱

③CO2在饱和的NaHCO3溶液中几乎不溶解

【提出猜想】猜想Ⅰ:NaOH

猜想Ⅱ:Na2CO3

猜想Ⅲ:NaOH和Na2CO3

【设计实验】

实验操作

实验现象

 

步骤①:样品全部溶解

步骤②:观察到现象A

 

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    I have a friend named Monty Roberts who owns a horse ranch(牧马场). The last time I was there he told me his story. When he was young, his family was too poor to have a house to live in.As a result , when he was in high school, all the students were asked to write a paper about what they wanted to be and do when they grew up. That night he wrote a seven-page paper describing his goal of owning a horse ranch. He also drew a picture to show a 4,000-square-foot house that would sit on a beautiful farm. The next day he handed it in to his teacher. Two days later he received his paper back. On the front page was a large red F. Roberts asked, “Why did I receive an F?” He teacher said, “This is an unrealistic dream for a young boy like you. Owning a horse ranch requires a lot of money.” Then the teacher added, “If you will rewrite this paper with a more realistic goal, I will reconsider your grade.”

    The boy went home and thought about it for a long and hard time. He asked his father what he should do. His father said, “ Look, son, you have to make up your own mind on this. However, I think it is a very important decision for you.”Finally, after sitting with it for a week, the boy turned in the same paper, making no changes at all. He told his teacher “you could keep the F and I still keep my dream”.

    He tells me this story because I am sitting in his 4,000-square-foot house in the middle of the 200-acre horse ranch. “I still have that school paper now.” He added, “The best part of the story is that two years ago that  teacher brought 30 kids to camp out on my ranch for a week.” When the teacher was leaving, he said, Look, Monty, I can tell you this now. When I was your teacher, I was something of a dream stealer.During those years I stole a lot of kids' dreams. Luckily, you had enough gumption not to give up on yours. .”