题干

为测定碳酸钙粉末与稀盐酸反应生成二氧化碳的质量(假设二氧化碳全部从溶液中逸出,不考虑试剂的挥发),实验如下:将小烧杯中的稀盐酸倒入盛有5g碳酸钙粉末的大烧杯中,记录天平的示数直至充分反应(如图二),天平示数与反应时间的关系如图三所示。

①分析图三可知t3时反应已停止,理由是____;

②如果5g碳酸钙粉末完全反应,产生多少摩尔的二氧化碳?(根据化学方程式列式计算)____;

③天平示数m的值____140.00g。(用“>”“=”、“<”、“≤”、“≥”等符号表示)。

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天平示数不再发生变化,0.05mol,=

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A Book Review—The Snake-Stone by Berlie Doherty

    The setting: Urban England (the cities), but also rural England (the countryside) including remote English villages.

    The theme: The main theme is a teenage search of self-discovery, in this case the search for a mother from whom the hero was separated at an early age. Its other concerns are love, getting on with others, being persistent and courageous and trying to deal with doubts, troubles and worries. As the book moves to a close, James' swimming coach says to him: “You are not like a kid obeying instructions any more. You are diving like a young man who knows where he is going.”

    The characters: James is the hero of the story. He is a championship diver, and has a comfortable life with his foster parents (养父母). Yet he also has the qualities to take him on a long journey to find his birth mother. The other characters in The Snake-Stone, James' parents, his diving instructor, best friend, the villagers, people he meets on his journey, are pictured realistically.

    The turning point: The turning point in the story comes while James' foster parents are away in London, and he wonders about the identity of his birth mother. The only clue he has is a fossil, “the snake stone” which she left behind along with a note on which she had written: “Take good care of Sammie. It was written on a torn envelope with parts of an address still there.

    The journey: Instead of going to London, James decides to find his birth mother. With help from his geography teacher, James sets out for the remote country village where his mother might be found. James has painful, challenging, but also humorous and happy travels. The mother he finally meets, Anne, has a minor yet powerful voice in the novel. He comes to understand why she left him at a stranger's door fifteen years before. Although the meeting is not long, it leaves him with a feeling of completeness. As a journey of self-discovery The Snake-Stone also provides its readers with a happy ending. Its hero says, on returning to his foster parents, “I was home.”