问题 实验题

实验室有一包暗红色粉末样品可能是CaCO3、Fe2O3或FeO的混合物。后经测定已确定不存在FeO。

Ⅰ.某学生想自己设计实验方案,以证明样品中确实没有FeO.除样品外,实验室只提供以下试剂:KMnO4溶液、稀盐酸、稀硫酸、KSCN溶液、NaOH溶液和双氧水.你认为要完成该实验所选择的试剂是_________,请你描述实验操作时的步骤、实验现象和结论:_____________________。

Ⅱ.测定混合物中Fe2O3的含量实验室可用多种方法测出上述样品中Fe2O3的质量分数.现有学生准备用题图中各装置按一定顺序连接成一套完整的组合装置来进行实验以测定Fe2O3的质量分数.

请根据题意回答下列问题:    

(1)装置的连接顺序是_________(填字母,每个装置只能用一次)    

(2)实验过程中需要持续通入空气,其作用除可以起到“搅拌”A、D中反应物达到充分反应外,还有一个重要作用是_________________    

(3)下列各项措施中,能提高测定准确度的是__________(填标号)     

a.在加入盐酸之前,应该排尽装置内的CO2气体     

b.快速加入盐酸     

c.在B中装入浓硫酸     

d.在B中装入NaOH溶液     

e.D之后增添盛有饱和碳酸氢钠溶液的洗气装置    

(4)实验室准确称取26.0g固体样品装入D中,充分反应后,测得A中沉淀质量为19.7g,则样品中Fe2O3的质量分数为__________

 (5)在进行实验方案评价时,有学生认为不必测定A中的沉淀质量,而只要测出装置A在吸收反应产生的气体前后的质量差,就能完成实验要求.实验证明,若用此法测得Fe2O3的质量分数将______(填“偏高”、“偏低”、“不变”)

答案

Ⅰ.KMnO4溶液、稀硫酸;取少量样品溶于试管中,配成溶液后,再滴入几滴稀硫酸和几滴KMnO4溶液,只要溶液不褪色或不变浅,即说明样品中无FeO

Ⅱ.(1)BDAC;(2)将反应产生的CO2气体尽可能彻底的赶入装置A中,使之完全被Ba(OH)2溶液吸收;(3)ad;(4)61.5%;(5)偏低

选择题
阅读理解

Why play games? Because they are fun, and a lot more besides. Following the rules…planning your next move...acting as a team member…these are all “game” ideas that you will come across throughout your life.

Think about some of the games you played as a young child, such as rope-jumping and hide-and-seek. Such games are entertaining and fun. But perhaps more importantly, they translate life into exciting dramas that teach children some of the basic rules they will be expected to follow the rest of their lives, such as taking turns and cooperating (合作) .

Many children’s games have a practical side. Children around the world play games that prepare them for work they will do as grown-ups. For instance, some Saudi Arabian children play a game called bones. Which sharpens the hand-eye coordination(协调)needed in hunting.

Many sports encourage national or local pride. The most famous games of all, the Olympic Games, bring athletes from around the world together to take part in friendly competition. People who watch the event wave flags, knowing that a gold medal is a win for an entire country, not just the athlete who earned it. For countries experiencing natural disasters or war, an Olympic win can mean so much.

Sports are also an event that unites people. Soccer is the most popular sport in the world. People on all continents play it—some for fun and some for a living. Nicolette Iribarne, a Californian soccer player, has discovered a way to give people hope through soccer. He created a foundation(基金会) to provide poor children with not only soccer balls but also a promising future.

Next time you play your favorite game or sport, think about why you enjoy it, what skills are needed, and whether these skills will help you in other aspects of your life.

小题1:Through playing hide-and-seek, children are expected to learn to ________.

A.be a team leader

B.obey the basic rules

C.act as a grown-up

D.predict possible danger小题2:The underlined part in Paragraph 2 most probably means that games can________.

A.describe life in an exciting way

B.turn real-life experiences into a play

C.make learning life skills more interesting

D.change people’s views of sporting events小题3:According to the passage, why is winning Olympic medals so encouraging?

A.It makes people have a deep love for the country.

B.It proves the exceptional skills of the winners.

C.It helps the country out of natural disasters.

D.It earns the winners fame and fortune.小题4:Iribarne’s goal of forming the foundation is to _______.

A.bring fun to poor kids

B.provide soccer balls for children

C.give poor kids a chance for a better life

D.appeal to soccer players to help poor kids小题5:What can be learned from the passage?

A.Games benefit people all their lives.

B.Sports can get all athletes together.

C.People are advised to play games for fun.

D.Sports increase a country’s competitiveness.