问题 填空题

人类常从矿石中获取金属材料。

(1)铁是冶炼最多的金属。工业炼铁主要反应的化学方程式是:Fe2O3+3CO=高温=2Fe+3CO2,反应中的氧化剂是_____________。该反应中所涉及的物质中,属于单质的是________.常用于灭火的是___________.

(2)铜是人类利用较早的金属,木炭与氧化铜反应生成二氧化碳的化学方程式是______________________,反应后固体的质量_____________(填“增大”、“减小”或“不变”)

(3)铝在现代生活中得到广泛的应用。炼铝原料水铝石的主要成分是Al(OH)3,Al(OH)3由________种元素组成,2mol Al(OH)3中含有_____g氧元素。

(4)金属冶炼通常使矿石中金属元素转变为_______(填“化合”或“游离”)态。

答案

(1)Fe2O3或氧化铁(2)Fe或铁

(3)CO2或二氧化碳(4)C+2CuO△2Cu+CO2

(5)减少(6)3或三(7)96(8)游离

(1)在这个反应中,我们可以根据得氧或失氧来判断物质是氧化剂或还原剂。氧化剂是指在氧化还原反应中失去氧元素的物质。还原剂是指在氧化还原反应中得到氧元素的物质。

(2)该反应中属于单质的是金属铁(Fe),

(3)能用于灭火的是二氧化碳(CO2)气体,利用二氧化碳不燃烧也不支持燃烧的性质。

(4)木炭与氧化铜可以在加热的条件下反应生成二氧化碳和铜。(利用了木炭的还原性)

所以反应的化学方程式为:C+2CuO 2Cu+CO2

(5)反应前的固体是CuO,反应后生成的固体是Cu,相当于CuO的基础上去掉了氧元素的质量,所以反应后固体的质量减少。

(6)根据Al(OH)3的化学式可知,其中含有Al、O、H等三种元素。

(7)根据化学式可知,2mol Al(OH)3中含有氧元素的物质的量为6 mol。其质量为16g/ mol*6 mol=96g。

(8)金属冶炼目的是把金属的化合物通过反应转化为金属单质,即金属元素由化合态转化为游离态。

点评:本题利用常见的物质考查了氧化还原反应、化学方程式的书写、元素的化合态与游离态等知识点,要求准确掌握相关知识。

单项选择题

I’ve recently turned fifty, which is young for a tree, midlife for an elephant, and ancient for a sportsman. Fifty is a nice number for the states in the US or for a national speed limit but it is not a number that I was prepared to have hung on me. Fifty is supposed to be my father’s age, but now I am stuck with this number and everything it means.
A few days ago, a friend tried to cheer me up by saying, "Fifty is what forty used to be. "He had made an inspirational point: Am I over the hill People keep telling me that the hill has been moved, and I keep telling them that the high-jump bar has dropped from the six feet I once easily cleared to the four feet that is impossible for me now.
"Your are not getting older, you are getting better," says Dr. Joyce Brothers. This, however, is the kind of doctor who inspires a second opinion.
And so, as I approach the day when I cannot even jump over the tennis net, I am moved to share some thoughts on aging with you. I am moved to show how aging feels to me physically and mentally. Getting older, of course, is obviously a better change than the one that brings you eulogies (颂词,悼词). In fact, a poet named Robert Browning considered it the best change of all:
Grow old along with me!
The best is yet to me.
Whether or not Browning was right, most of my first fifty years have been golden ones, so I will settle for what is ahead being as good as what has gone by. I find myself moving toward what is ahead with a curious blend (混合) of both fighting and accepting my aging, hoping that the philosopher(哲学家) was right when he said, "Old is always fifteen years from now. \

The author seems to tell us in Paragraph I that ______.

A.time alone will tell

B.time goes by quickly

C.time will show what is right

D.time makes one forget the past

单项选择题