题干

  “Cool" is a word with many meanings.Its old meaning is used to express a temperature that is a little bit cold.As the world has changed,the word has had many different meanings.
  “Cool"can be used to express feelings of interest in almost everything When you see a famous car in the street,maybe you will say,“It's cool." You may think,“He's so cool," when you see your favorite footballer.
    We all maximize(扩大) the meaning of “cool". You can use it instead of many words such as “new" or "surprising".Here's an interesting story we can use to show the way the word is used.A teacher asked her students to write about the waterfall(瀑布)they had visited.On one student's paper was just the one sentence, “It's so cool.Maybe he thought it was the best way to show what he saw and felt. But the story also shows a lack of words.Without “cool”,some people have no words to show the same meaning.So it is quite important to keep some credibility(可信性).Can you think of many other words that make your life as colorful as the word "cool"? I can.And I think they are also very cool.

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同类题3

硫酸亚铁铵的化学式为(NH42SO4•FeSO4•6H2O,是浅绿色晶体,商品名为莫尔盐,易溶于水,不溶于乙醇.

温度/℃

溶解度/g

0

10

20

30

40

50

60

(NH42SO4

70.6

73.0

75.4

78.0

81.0

88.0

FeSO4•7H2O

15.7

20.5

26.5

32.9

40.2

48.6

(NH4)SO4FeSO4•6H2O

12.5

17.2

21.6

28.1

33.0

40.0

完成下面的实验报告:

【实验原理】

【实验用品】

10%Na2CO3溶液、Fe屑、3mol/LH2SO4、(NH42SO4固体、蒸馏水、无水乙醇.锥形瓶、蒸发皿、酒精灯、玻璃棒、烧杯、铁架台、漏斗、托盘天平、量筒、滤纸.

【实验步骤】

(1)Fe屑的处理和称量

称取3g铁屑,放入锥形瓶,用10%Na2CO3溶液,除去Fe屑表面的油污,将剩余的碱液倒掉,用蒸馏水把Fe冲洗干净,干燥后称其质量m1g.

(2)FeSO4的制备

将称量好的Fe屑放人锥形瓶中,加入15mL 3mol/LH2SO4,加热10min后(有氢气生成,用明火加热注意安全).       a       ,并用少量热水洗涤锥形瓶及滤纸,将滤液和洗涤液一起转移至蒸发皿中.将滤纸上的固体干燥后称得质量为m2g.

①a处的操作是____ ;

②制取FeSO4时,加入的Fe为什么要过量?(用离子方程式表示)____  

(3)(NH42SO4•FeSO4•6H2O的制备

根据FeSO4的物质的量,计算并称取(NH42SO4固体,并将其加入上面实验的蒸发皿中,缓缓加热,浓缩至表面出现结晶薄膜为止.____ ,得到硫酸亚铁铵的晶体.过滤后用无水乙醇洗涤晶体,除去其表面的水分,称量得到的晶体质量为m3g.

①b处的操作是____ ;②制备莫尔盐晶体时,为什么不能将溶液蒸发至干?____

(4)产品检验

微量Fe3+的分析.称0.5g产品置于25mL比色管中,加水溶解后加1mL 25%的KSCN溶液,继续加水至25mL刻度,摇匀,与教师所给标准对比,评价产品质量.写出该过程所发生反应的离子方程式:____ 

【实验记录】

起始铁的质量m1/g

反应后铁的质量m2/g

莫尔盐的质量

产率

理论产量/g

实际产量m3/g

5.0

2.2

c

14.7

d