题干

用NaOH溶液处理铝土矿(主要成分为Al2O3),反应的化学方程式:Al2O3+2NaOH=2NaAlO2+H2O.欲对含Al2O3 204吨的铝土矿进行处理(杂质不参与反应),需消耗800吨NaOH溶液,求该NaOH溶液的溶质质量分数?
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答案(点此获取答案解析)

解:设理论上需要消耗NaOH的质量为x

Al2O3+

2NaOH=2NaAlO2+H2O

102

同类题3

任务型阅读

    My mother is a diligent and kind woman. She is very busy from morning till night. As a teacher, she works hard.____ Both my brother and I love her dearly as she loves us.

    My mother has been teaching math at a middle school in my hometown. She goes to work early in the morning and does not return home until late in the afternoon. ____ She treats them with patience and teaches them well. For her excellent quality and very good teaching results, she has been elected as a model teacher several times.

    ____ Every day, when she comes back home from work, she sets about doing housework, sweeping the living room and bedrooms or cleaning the furniture, and putting everything in good order. She seems to be busy all the time. As she has been very busy working every day, she looks older than her age. But she looks as cheerful and happy as ever. Mother never buys expensive dresses for herself, but she often buys some inexpensive but high quality clothes for us.____She just eats a plain meal outside when she is too busy to cook herself. She lives a busy yet simple life, without any complaints.

    Often she says to us, “Work while you work, and play while you play. That is the way to be happy and gay. If you do not work, you will become lazy and be of no use to society”. What a piece of good advice this is! ____This advice of hers will always serve as a guide to my behavior. My mother is great indeed, and I always feel proud of her.

A. She enjoys listening to classical music.

B. As a mother, she takes good care of us and gives us every comfort.

C. She loves her students and cares for them.

D. She never goes to expensive restaurants to enjoy meals.

E. My mother is hard-working and never wastes money.

F. I never forget it and always bear it in my mind.

G. Can you tell us something about your mother?

同类题5

阅读下面的文言文,完成下面题目。

    韦凑字彦宗,京兆万年人。永淳初,解褐婺迁杨州法曹州参军事。徙资州司兵,观察使房昶才之,表于朝。州人孟神爽罢仁寿令,豪纵,数犯法,交通贵戚,吏莫敢绳,凑按治,杖杀之,远近称伏。入为相王府属,时姚崇兼府长史,尝曰:“韦子识远文详,吾恨晚得之。”六迁司农少卿。忤宗楚客,出为贝州刺史。睿宗立,徙太府,兼通事舍人。

    景云初,作金仙等观,凑谏,以为:“方农月兴功,虽赀出公主,然高直售庸,则农人舍耕取顾,趋末弃本,恐天下有受其饥者。”不听。凑执争,以“万物生育,草木昆蛟伤伐甚多,非仁圣本意”。帝诏外详议。中书令崔缇、侍中岑羲曰:“公敢是耶?”凑曰:“食厚禄,死不敢顾,况圣世必无死乎?”朝廷为减费万计。出为陕、汝、岐三州刺史。

    开元初,欲建碑靖陵,凑以古园陵不立碑,又方旱不可兴工,谏而止。迁将作大匠。诏复孝敬皇帝庙号义宗,凑谏曰:“传云:‘必也正名。’礼:祖有功,宗有德,其庙百世不毁。历代称宗者,皆方制海内,德泽可尊,列于昭穆,是谓不毁。孝敬皇帝未尝南面,且别立寝庙,无称宗之义。”遂罢。

    迁右卫大将军,玄宗谓曰:“故事,诸卫大将军与尚书更为之,近时职轻,故用卿以重此官,其毋辞!”寻徙河南尹,封彭城郡公。会洛阳主簿王钧以赇抵死,诏曰:“两台御史、河南尹纵吏侵渔,《春秋》重责帅,其出凑曹州刺史,侍御史张洽通州司马。”久之,迁太原尹,兼北都军器监,边备修举,诏赐时服劳勉之。及病,遣上医临治。卒,年六十五。

(节选自《新唐书•韦凑传》)