问题 填空题

10℃时加热NaHCO3的饱和溶液,测得该溶液的pH发生如下变化:

1、甲同学认为,该溶液的pH升高的原因是HCO3-的水解程度增大,故碱性增强,该反应的离子方程式为_____________________________________。

2、乙同学认为溶液pH升高的原因是NaHCO3受热分解,生成了Na2CO3,并推断Na2CO3的水解程度____________(填“大于”或“小于”)NaHCO3,该分解反应的化学方程式为___________________________。

3、丙同学认为甲、乙的判断都不充分.丙认为:

(1)只要在加热煮沸的溶液中加入足量的试剂X,若产生沉淀,则__________(填“甲”或“乙”)判断正确.试剂X是________。

A.Ba(OH)2溶液 B.BaCl2溶液 C.NaOH溶液 D.澄清的石灰水

(2)将加热后的溶液冷却到10℃,若溶液的pH________(填“高于”“低于”或“等于”)8.3,则________(填“甲”或“乙”)判断正确。

(3)查阅资料,发现NaHCO3的分解温度为150℃,丙断言________(填“甲”或“乙”)的判断是错误的,理由是__________________________________________________________。

答案

1、HCO3-+H2O==H2CO3+OH- 

2、大于;2NaHCO3Na2CO3+CO2↑+H2O

3、(1)乙;B 

     (2)等于;甲(或高于乙) 

     (3)乙;常压下加热NaHCO3的水溶液,溶液的温度达不到150℃

名词解释
阅读理解

When people want to know about the weather, they usually go to there radios, TVs, newspapers, or to the Internet. However, you can also find many weather signs among wildlife, because of their highly developed senses. Drops in air pressure(压力) produce an effect on small animals in many ways. Mice and deer are good weather indicators. People who spend a lot of time outdoors have observed that, before a storm, field mice come out of their holes and run around, Deer leave high ground and come down from the mountains.

Birds are especially good weather indicators because they also show the effect of a pressure drop in many ways. For example, some birds become irritable(急躁的)and quarrelsome and will fight over a piece of bread. Other birds chirp(叽叽喳喳)and sing just before a storm. It seems they know they won’t get another chance for an hour or two. Birds also seek safe places before a storm, You will sometimes see birds settling in trees or gathering together on a wire close to a building. Pre-storm low pressure makes the are so thin that birds have difficulty flying.

It is unusual to see many birds flying overhead in the summertime, rather than during the periods in the spring or autumn. Watch for other weather signs if you see this. If they fly in the wrong direction, they may be flying ahead of a storm.

By paying closer attention to some important signs in nature, we can become better prepared for any kind of weather.

小题1:The word“indicators”in paragraph I probably means ________.

A.maps

B.services

C.signs

D.stations小题2:There will be a storm if birds __________ .

A.make more noise than usual

B.fly in different directions

C.come down from tall trees

D.share a piece of bread小题3:How can birds sense the coming of a storm?________

A.By feeling a drop in air temperature.

B.By noticing the change of wind directions.

C.By feeling a drop in air pressure.

D.By noticing the movements of other animals.小题4:The best title for the text would be ________         .

A.Signs of a Storm

B.Drops in Air Pressure

C.Animals’Sharp Senses

D.Nature’s Weather Signs