问题 问答题

某研究小组为比较Al和Fe的金属性强弱,设计了图1所示的装置,甲中锥形瓶内盛放的是100ml稀盐酸(反应前后溶液体积变化可以忽略不计).

(1)若要比较产生气体的快慢有两种方法,一种是比较产生相同体积气体所需的时间,另一种是比较______.

(2)为了确保“Al和Fe的金属活动性不同是导致产生气体速率不同的唯一原因”,实验时需要控制好反应条件.实验时除需保证甲中液体的体积、物质的量浓度和温度相同外,还需保证______.

(3)实验测得产生气体的速率(v)与时间(t)的关系如图2所示,则t1~t2时间内速率逐渐加快说明该反应是______(填放热或吸热)反应,t2~t3时间内速率逐渐减慢的主要原因是______.

(4)能使甲中的反应停止的操作是______.

答案

(1)由v=

△V
△t
知,反应速率与气体的体积和时间有关,所以一种是固定体积比较时间,另一种是固定时间比较体积.

故答案为:相同时间内产生气体体积大小;

(2)影响化学反应速率的因素有反应物的浓度、溶液的温度、固体的表面积等,所以还需保证Al和Fe表面积相同.

故答案为:Al和Fe表面积相同;

(3)该反应是一个放热的反应,随着反应的进行,放出的热量越多,溶液的温度越高,温度越高反应速率越大;随着反应的进行,溶液中盐酸的浓度不断减小,浓度越小反应速率越小.

故答案为:放热;盐酸浓度不断减小;

(4)要想使反应停止,没有反应物即可,所以将铁丝或铝丝从溶液中拔出即可停止反应.

故答案为:铁丝或铝丝从溶液中拔出.

阅读理解

阅读理解。

    What do you think of a forest, what do you see? Just trees? Or do you see many other things, such as

singing birds, colorful plants and wild flowers?

    The forest is a whole of its own. It is full of many different living things. But even though they are all

different, they have one thing in common: they all need each other in order to live on.

    The trees feed the forest "people" by making food in their leaves, by using sunlight to join water and

minerals from the soil and air. Their deep network of roots joins the soil together and stops it from dying

out, making it possible for living things to live in it.

    Human beings are like the living things in the forest. We need one another in order to live. We need the

farmers to grow our food, railroad and truck drivers to bring it to our shops and clerks to sell it to us. We

need people to prepare our food and cook it and others to take our waste things away. Then, of course, we

need doctors, nurses, government leaders, mailmen, telephone operators, and many others.

    We also need other human being in another way. We need people for friendship, to talk over our problems,

exchange ideas. Think how lonely and unhappy you would be if you lived all alone.

    Life is a matter of giving and taking. We need to help other people as much as we need other people to

help us. Think what a good feeling you have when you have done something for someone else. You know,

being a volunteer is so great.

1. According to the text, colorful plants and flowers live on ______. [ ]

A. the leaves of the trees

B. water and minerals

C. the soil and air

D. all of the above

2. It is the _____ that make it possible for living things to live in the forest. [ ]

A. trees

B. birds

C. plants

D. farmers

3. According to the writer, human being are            the forest "people". [ ]

A. different from

B. like

C. dislike

D. unhappy with

4. The write mainly wants to tell us _____. [ ]

A. we need people for friendship

B. we need one another in order to live

C. the forest is a whole world of its own

D. the forest is full of different living things

5. Which one is the relationship between a forest and your life? [ ]

A. We are trees in the forests.

B. We like the living things in the forest.

C. We need farmers to grow our food in the forest.

D. We are the same as the forest: We need each other to live on.

单项选择题