问题 填空题

6分)某实验小组用下图装置研究CO2的性质。

提示:①忽略块状大理石中杂质对本实验的影响

②碱性碳酸钠溶液与中性氯化钙溶液能发生复分解反应

(1)如下图所示,装入药品,打开K,玻璃管b中反应的化学方程式为__________,导管口处的现象是______________。

(2)关闭K,一段时间后反应停止。反应能够停止的原因是______________。

(3)反应停止后,向a中滴入酚酞溶液,并加入一定量碳酸钠固体,充分反应后 a中溶液呈红色。打开K,待a、b中液面相平后立即关闭K,轻轻振荡b管。一段时间后观察到的现象是____________,最终b中红色褪去,此时b中溶液的溶质可能为__________。

答案

(1)CaCO3 + 2HCl ="=" CaCl2 + H2O + CO2↑ , 紫色石蕊小花变红;(2)大理石与稀盐酸反应产生CO2,使b管中的气压增大,b中液体被压入a中,大理石与稀盐酸脱离接触,所以反应停止。(3)液面上升,溶液变浑浊。NaCl 或 NaCl、CaCl2(酚酞)(0或2分)

题目分析:(1)打开K,玻璃管b中反应的化学方程式为CaCO3 + 2HCl ="=" CaCl2 +H2O + CO2↑,导管口处的现象是紫色石蕊小花变红;(2)关闭K,一段时间后反应停止。反应能够停止的原因是大理石与稀盐酸反应产生CO2,使b管中的气压增大,b中液体被压入a中,大理石与稀盐酸脱离接触,所以反应停止。(3)反应停止后,向a中滴入酚酞溶液,并加入一定量碳酸钠固体,充分反应后 a中溶液呈红色。打开K,待a、b中液面相平后立即关闭K,轻轻振荡b管。一段时间后观察到的现象是液面上升,溶液变浑浊。,最终b中红色褪去,说明没有碱性物质存在,此时b中溶液的溶质可能为。NaCl 或 NaCl、CaCl2

阅读理解

阅读理解

     Our children and grandchildren may not have a chance to visit many of the most famous places around

the world. War, weather, age, traffic and pollution damage these famous places. Looking after these places often costs more than one country can afford.

     In the early 1970s, world governments decided that if they joined together, they would be able to

preserve our history. If every country paid some money, they said, it would be possible to look after

important historic places. Also, if they discovered that a monument needed urgent help, they would have

money for repairs. For these reasons, countries around the world united to form the World Heritage

Organization in 1972. Today, the organization helps to maintain and restore the most important places from our history.

     However, one of the biggest problems for historic places is vandalism. People sometimes enter the sites and destroy or damage the buildings. At some sites, such as Stonehenge(巨石阵) in England, governments have built high fences to protect the site from vandals.

     There are many different ideas about how to solve the problem of vandalism. Stone experts say that if

guards patrolled the sites, vandals would not be able to get in. Some experts say that if they fixed more

television cameras, they would not need so many guards. Other experts say that the best solution is

education. If people learned to respect history, they would not destroy or damage it. They would also want to spend money looking after old places. For this reason, the World Heritage Organization helps to spread information about the value of historic sites.

1. According to this passage, ____ is NOT mentioned in Paragraph 1 for the reasons why the famous

places are damaged?  

A. people's awareness            

B. pollution  

C. war and climate              

D. traffic

2. Which of the following shows us the action of vandalism?

A. Governments build high fences to protect the site from vandals

B. Guards patrolled the sites and they fixed more television cameras

C. People enter the sites and cause damage to the buildings

D. They collect as much money as they can to preserve the buildings

3. What's the best way to solve the biggest problem of preserving our history?

A. Every country spends more money looking after these places

B. To form the World Heritage Organization

C. Too many guards are needed to prevent vandals getting in

D. To make people know more about the value of historic sites

单项选择题 B1型题