问题 问答题

(1)用滴管将新制的饱和氯水逐滴滴入含酚酞的氢氧化钠的稀溶液中,当滴到最后一滴时,红色突然褪去.产生该现象的原因可能有两个:

①是由于______;②是由于______.

用实验证明红色褪去的原因是①或者是②,其方法是:____________.

(2)在一定条件下氯气可与氯化铵发生反应:xCl2+yNH4Cl→yNCln+(x+y)HCl,当消耗6.72L标准状况下的氯气时,生成0.10mol氮的氯化物,则此氮的氯化物的化学式为______.

答案

(1)因酚酞遇碱变红,将新制氯水慢慢滴入含酚酞的NaOH稀溶液中,当滴到最后一滴时红色突然褪去,则可能为氯水中的酸性与碱反应,使NaOH减少,而能使溶液由红色变成无色;

也可能为氯水中的次氯酸有漂白性,使溶液由红色变成无色.

因次氯酸漂白后的溶液再加NaOH溶液不会恢复颜色,向褪色溶液中再滴加NaOH溶液,若红色再现,则是①;若红色不再现,则是②.

故答案为:氯水中H+与碱中和;氯水中HClO强氧化性所致;向褪色溶液中再滴加NaOH溶液,若红色再现,则是①;若红色不再现,则是②;

(2)xCl2+yNH4Cl→yNCln+(x+y)HCl,根据氧化还原反应中得失电子数相等配平该方程式,

(n+3)Cl2+2NH4Cl=2NCln+8HCl

  n+3           2   

  

6.72L
22.4L/mol
0.10mol

所以n=3,该氯化物的化学式为NCl3

故答案为:NCl3

阅读理解

Many people like to travel by plane, but I don’t like it because an airport is usually far from the city. You have to get there early and wait for hours for the plane to take off (起飞) and it is often late. You can’t open the window. You can’t choose(选择) the food. Planes are fast, but it still takes hours to get out of the airport and into the city.

I like traveling by train. I think trains are safe. The stations are usually in cities. When you can’t catch a train, you can catch another one. You can walk around in the train. You can see many interesting things on your way. I know it takes a little more time.

I also like cars. You can start your trip when you want to, and you don’t need to reach a train station or a bus stop. Also you can carry many things with you in a car. But sometimes there are too many cars on the road.

小题1:Why do many people like to travel by plane?

A.Because it is fast.

B.Because you can walk around in the plane.

C.Because it is safe.

D.Because you can carry many things in a plane.小题2:Which is not the good thing about the train?

A.It is safe.

B.It takes a little more time.

C.The stations are usually in cities.

D.You can see interesting things on your way.小题3:If you want to take a lot of things with you, what do you take to go out?

A.A bus.

B.A car.

C.A train.

D.A ship.小题4:What does the underlined word “reach ”mean?

A.get off

B.get on

C.get to

D.get up小题5:What does the writer think of the plane ,the train and the car?

A.He likes to take a train because it takes a little more time.

B.He likes to take a car because he has a car.

C.He doesn’t like traveling by plane just because he couldn’t choose the food on the plane.

D.He thinks it takes a lot of time to go to and get out of the airport.

问答题 简答题