试题与答案

钢铁是使用最多的金属材料. (1)生铁和钢都是铁合金,其中含碳量较高的是____

题型:问答题

题目:

钢铁是使用最多的金属材料.

(1)生铁和钢都是铁合金,其中含碳量较高的是______.

(2)人们常用“铜墙铁壁”来形容物体的坚固,但铁在一定条件下也能发生各种反应.如铁丝能够在氧气中燃烧,该反应的化学方程式是______.

(3)向mg氧化铜粉末中逐滴加入某浓度的稀硫酸,当加入的稀硫酸为100g时氧化铜恰好完全溶解,得到蓝色溶液A,向溶液A中再加入一定量的铁粉,充分反应,过滤,得到滤渣B和滤液C.向滤渣B中加入足量的稀硫酸,有气泡冒出,充分反应后,剩余固体物质的质量为12.8g.

①滤渣B的化学式是______,滤液C的溶质的名称是______.

②m=______.

③列式计算稀硫酸中溶质的质量分数.

④蓝色溶液A中溶质的质量分数______(精确到小数点后一位).

答案:

(1)生铁和钢都是铁合金,其中含碳量较高的是生铁;故填:生铁;

(2)铁丝能够在氧气中燃烧生成四氧化三铁,反应的化学方程式是3Fe+2O2

 点燃 
.
 
Fe3O4;故填:3Fe+2O2
 点燃 
.
 
Fe3O4

(3)氧化铜和硫酸反应生成硫酸铜和水,得到蓝色溶液A,向溶液A中再加入一定量的铁粉,铁和硫酸铜反应生成硫酸亚铁和铜;充分反应,过滤,得到滤渣B和滤液C.向滤渣B中加入足量的稀硫酸,有气泡冒出说明铁粉有剩余,所以滤渣B是铁和铜的混合物,滤液C就是硫酸亚铁溶液;而剩余固体物质就是铜,其质量是12.8g,所以氧化铜的质量=12.8g÷

64
16+64
×100%=16g.

设稀硫酸中溶质的质量为x,生成硫酸铜的质量为y

CuO+H2SO4═CuSO4+H2O

80   98    160

16g   x     y

80
16g
=
98
x

x=19.6g

80
16g
=
160
y

y=32g

稀硫酸中溶质的质量分数=

19.6g
100g
×100%=19.6%

蓝色溶液A中溶质的质量分数=

32g
16g+100g
×100%=27.6%

答:稀硫酸中溶质的质量分数为19.6%,蓝色溶液A中溶质的质量分数27.6%.

故答案为:①Cu、Fe;硫酸亚铁溶液;②16;③19.6%;④27.6%.

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题型:问答题

It is hard to predict how science is going to turn out, and if it is really good science it is impossible to predict. If the things to be found are actually new, they are by definition unknown in advance. You cannot make choices in this matter. (46)You either have science or you don’t, and if you have it you are obliged to accept the surprising and disturbing pieces of information, along with the neat and promptly useful bits.

The only solid piece of scientific troth about which I feel totally confident is that we are profoundly ignorant about nature. Indeed, I regard this as the major discovery of the past hundred years of biology. It is, in its way, an illuminating piece of news. (47)It would have amazed the brightest minds of the 18th century Enlightenment to be told by any of us how little we know and how bewildering the way ahead seems. (48)It is this sudden confrontation with the depth and scope of ignorance that represents the most significant contribution of the 20th century science to the human intellect. In earlier times, we either pretended to understand how things worked or ignored the problem, or simply made up stories to fill the gaps. Now that we have begun exploring in earnest, we are getting glimpses of how huge the questions are, and how far from being answered. Because of this, we are depressed. (49)It is not so bad being ignorant if you are totally ignorant; the hard thing is knowing in some detail the reality of ignorance, the worst spots and here and there the not-so-bad sports, but not true light at the end of the tunnel nor even any tunnels that can yet be trusted.

But we are making a beginning and there ought to be some satisfaction. There are probably no questions we can think up that can’t be answered, sooner or later, including even the matter of consciousness. (50)To be sure, there may well be questions we can’t think up, ever, and therefore limits to the reach of human intellect, but that is another matter. Within our limits, we should be able to work our way through to all our answers if we keep at it long enough, and pay attention.

(46)You either have science or you don’t, and if you have it you are obliged to accept the surprising and disturbing pieces of information, along with the neat and promptly useful bits.

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