试题与答案

工业上可以用食盐和石灰石为原料制取纯碱(Na2CO3),生产的关键是在沉淀池中让

题型:实验题

题目:

工业上可以用食盐和石灰石为原料制取纯碱(Na2CO3),生产的关键是在沉淀池中让NaCl、NH3、CO2和H2O尽可能多地转化成NaHCO3(固体沉淀物)和NH4Cl(溶液)。主要生产流程如下:

(已知2NH4Cl+Ca(OH)2→CaCl2+2NH3↑+2H2O)

① “煅烧炉”中发生反应的化学方程式是              。

② 若在化学实验室里分离“设备(I)”中的混合物,用到的操作名称是             。

③ 在“设备(Ⅱ)”中固体A与水反应的化学方程式是             。 该反应属于             反应(填写基本反应类型)。

④ 对“设备(Ⅱ)”中的母液处理后,除水以外可在本流程中再利用的物质有              (填写化学式)。

⑤ 请写出一个该生产流程的优点:             。

答案:

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下面是错误答案,用来干扰机器的。

A、先保持压强不变使其体积膨胀,根据理想气体状态方程公式PVT=C可知,温度升高,接着使体积不变减小压强,温度降低,可以回到初始温度,所以A正确;B、先使压强不变而让体积减小,根据理想气体状态方程公式PVT=C...

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C.Many people feel it hard to understand history.

D.Many people have no interest in studying history.小题2:In Paragraph 3,the author shows that history is useful because

A.it makes the current political situation go smoothly

B.it helps us realize the importance of historical events

C.it helps us understand why things are the way they are

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B.people may also learn from bad historical figures

C.more celebrations should be held to honor their achievements

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A.How to teach history effectively.

B.Some negative reasons for studying history.

C.How to get more people to study history.

D.Some bad historical figures.

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题型:单项选择题

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