问题 问答题

为了培养自己解决实际化学问题的能力,李阳把家中厨房里的苏打和食盐各取若干混合,然后取该混合物进行实验.如果他称取42.8g混合物加入到116g稀盐酸中恰好完全反应,测得产生的气体质量为8.8g.请你帮小李计算:

(1)42.8g混合物中碳酸钠的质量?

(2)反应后所得溶液中溶质的质量分数?

答案

(1)设混合物中碳酸钠的质量为x.生成氯化钠的质量为y.

Na2CO3+2HC1=2NaC1+H2O+CO2

106
x
     
117
y
   
44
8.8

106
44
=
x
8.8g
,解之得:x=21.2g,

117
44
=
y
8.8g
,解之得:y=23.4g;

(2)反应后所得溶液中溶质的质量分数=

23.4g+42.8g-21.2g
42.8g+116g-8.8g
×100%=30%.

答:(1)42.8g混合物中碳酸钠的质量为21.2g;

(2)反应后所得溶液中溶质的质量分数是30%.

问答题
阅读理解

Astronauts on shorter shuttle missions often work very long days. Tasks are scheduled so tightly that break times are often used to finish the day's work. This type of schedule is far too demanding for long missions on the International Space Station (ISS). ISS crewmembers usually live in space for at least a quarter of a year. They work five days on and two days off to mimic the normal way they do things on Earth as much as possible. Weekends give the crew valuable time to rest and do a few hours of housework. They can communicate with family and friends by email, internet phone and through private video conferences.

While astronauts cannot go to a baseball game or a movie in orbit, there are many familiar activities that they can still enjoy. Before a mission, the family and friends of each ISS crewmember put together a collection of family photos, messages, videos and reading material for the astronauts to look at when they will be floating 370 kilometers above the Earth. During their mission, the crew also receives care packages with CDs, books, magazines, photos and letters. And as from early 2010, the internet became available on the ISS, giving astronauts the chance to do some "web surfing" in their personal time. Besides relaxing with these more common entertainments, astronauts can simply enjoy the experience of living in space.

Many astronauts say that one of the most relaxing things to do in space is to look out the window and stare at the universe and the Earth. Both the shuttle and the ISS circle the planet several times each day, and every moment offers a new view of the Earth's vast land mass and oceans.

小题1:What does the word "mimic" in Paragraph 1 probably mean?

A.copy

B.find

C.change

D.lose小题2:Which of the following best describes the families of the astronauts on the ISS?

A.They are impatient and annoyed.

B.They are worried and upset.

C.They are caring and thoughtful.

D.They are excited and curious.小题3:In the final paragraph, the author shows that astronauts ________.

A.love to see the Earth from space

B.find living in space a bit boring and tiring

C.regard space life as common

D.get more pleasure in space than on the Earth小题4:The passage mainly discusses how astronauts ________.

A.work for longer missions in space

B.spend their free time in space

C.observe the Earth from space

D.connect with people on the Earth