题干

某实验小组欲制取氧化铜并证明氧化铜能加快氯酸钾的分解,进行了如下实验:

(一)制取氧化铜

①称取2gCuSO4•5H2O研细后倒入烧杯,加10mL蒸馏水溶解;

②向上述CuSO4溶液中逐滴加入NaOH溶液,直到不再产生沉淀,然后将所得混合物转移到蒸发皿,加热至沉淀全部变为黑色;

③将步骤②所得混合物过滤、洗涤,晾干后研细备用.

回答下列问题:

(1)上述实验步骤中需要使用玻璃棒的是____ (填实验序号)

(二)证明氧化铜能加快氯酸钾的分解并与二氧化锰的催化效果进行比较

用右图装置进行实验,实验时均以生成25mL气体为准,其它可能影响实验的因素均已忽略,相关数据如下:

实验序号

KClO3质量

其它物质质量

待测数据

④

1.2g

无其他物质


⑤

1.2g

CuO  0.5g


⑥

1.2g

MnO2  0.5g


回答下列问题:

(2)上述实验中的“待测数据”指____ 

(3)若要证明实验⑤中干燥管内收集的气体是O2,可待气体收集结束后,用弹簧夹夹住B中乳胶管,拔去干燥管上单孔橡皮塞____ 

(4)为探究CuO在实验⑤中是否起催化作用,需补做如下实验(无需写出具体操作):

a.____  b.CuO的化学性质有没有改变.

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答案(点此获取答案解析)

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阅读理解

    More and more comment(评论) sections are being shut down online.

    Autumn Phillips had had enough. On August 19, the executive editor of the Quad-City Times in Iowa, and Illinois, US visited her website, qutimes. com, and saw a story about a man who had been shot to death. When she got to the readers' comments section at the end, she was shocked by what she saw. Below the story was a growing string of comments—a racist remark about democratic( 民主的) voters, a negative comment about police...So Phillips decided to do something she had been thinking about for a long time: she shut down the comment section.

    Phillips was not alone in making such a move. Last week, NPR announced it too was closing its online comments section. The decisions don't mean that the news outlets are no longer interested in what their audiences are thinking. Both stressed their eagerness to hear from readers and listeners on social networks. But both agreed that comments had deviated from their original intention. And so they had.

    In the early days of digital journalism, comments were seen as a key part of the new media, a wonderful opportunity for strengthening the dialogue between news producers and their audiences. It was a welcome change, given that for long many news organizations were far too separated from their readers. Much more back and forth conversation seemed like healthy and welcome evolutions. Sadly, that's not the way things turned out. Rather than a place for exchanging ideas, comments sections became the home of ugly name-calling, racism and anti-women language. Besides their poisonous quality, comments seem out of place today.

    “Since we made the announcement, I've received an outpouring of responses from our readers,”she says. “I've heard from parents whose children were hurt by our online comments. I've heard from people who said they wouldn't send in letters to the editor because they were attacked so fiercely by comments, and it wasn't worth it.”