问题 计算题

为测定某赤铁矿石中氧化铁的质量分数,小龙和他的同学用足量的一氧化碳与10g赤铁矿石样品充分反应(杂质不参与反应),并将生成的气体用一定量的氢氧化钠溶液完全吸收,该溶液总质量与反应时间的变化关系如图。

(1)上述反应产生二氧化碳的质量为__________g;

(2)计算该赤铁矿石中氧化铁的质量分数;

(3)若上述反应后剩余固体质量为m克,写出计算该赤铁矿石中氧化铁质量分数的表达式:_____________(用m表示)。

答案

(1)6.6

(2)解:设该样品中氧化铁质量为x  

3CO+Fe2O32Fe+3CO2      

 160                   3×44    

x                      6.6g 

   x=0.8g         

样品中氧化铁的质量分数为:  

 答:该样品中氧化铁质量分数为80%。    

(3) 

阅读理解

     Many people do not like to stay at home on holidays.They want to go out to see something

different or do something interesting.So people from the country come to the city and people

from the city go to the country for holidays.During the holidays trains,buses and planes are all

very busy.It is very hard to buy train tickets or air tickets.Many people take cars or buses for

traveling.

     Last May Day my family went to the country by car for our holiday.There was too much

traffic on the road,so we had to move very slowly.It took us about an hour to get out of the

town.After some time,we came to a hill.It was green and beautiful.We thought this was a good

place for a picnic,so we stopped and took the food,fruit and drinks out of the car.We sat down

and began to eat.Suddenly a strong wind blew and soon it started to rain.We had to run back

to our car and have our picnic in the car.Then we drove back home.What a sad holiday!

1.Which one is right in the following sentence?

A.Many people like staying at home on holidays.

B.People living in the city often go to another city for traveling.

C.It is easy to buy a ticket on holidays.

D.Many people take cars or buses for traveling.

2.How did they go to the country last May Day?

A.By car.

B.By train.

C.By bus.

D.On foot.

3.How long did they take to get out of the town?

A.Half an hour.

B.An hour.

C.One and half an hour.

D.Two hours.

4.Why did they go to the country?

A.To take some pictures.

B.To cook dinner.

C.To have a picnic.

D.To go sightseeing.

5.They felt ________ about the holiday.

A.happy

B.excited

C.unhappy

D.lucky

单项选择题