为了测定含杂质的氧化铁（杂质不参加反应）样品中氧化铁的质量分_爱下问搜题

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问题问答题

为了测定含杂质的氧化铁（杂质不参加反应）样品中氧化铁的质量分数，某同学称取该样品10g，并用如图所示的装置进行实验，得到如下两组数据：

	反应前	氧化铁完全反应后
A组	玻璃管和样品的质量43.7g	玻璃管和固体物质的质量41.3g
B组	广口瓶和澄清石灰水的质量180g	广口瓶和瓶内物质的质量186.2g

试回答：

（1）①你认为，应当选择______组的数据来计算样品中的氧化铁的质量分数，请写出具体解题过程．②请解释你不选另一组数据进行计算的原因______．

（2）这位同学所用装置的不足之处是______．

答案

（1）①在加热的条件下，一氧化碳还原氧化铁生成了铁和二氧化碳，质量守恒定律，玻璃管和样品在反应前后减少的质量就是氧化铁中氧元素的质量，再根据氧化铁中氧元素的质量分数，可求出氧化铁的质量，进而可以求出氧化铁的质量分数．所以，可以用A组数据进行进行计算；

氧化铁中氧元素的质量为：43.7g-41.3g=2.4g

氧化铁的质量为：2.4g÷

48

160

=8g

样品中的氧化铁的质量分数：

8g

10g

×100%=80%

②在B组中由于氢氧化钙是微溶于水的，可能吸收生成二氧化碳不完全，不能用来进行计算；

（2）由于一氧化碳有毒，能污染空气．所以，这位同学所用装置的不足之处是缺少尾气回收装置．

故答为：（1）①A，解题过程见上边；②氢氧化钙是微溶于水的，可能吸收生成二氧化碳不完全；（2）缺少尾气回收装置．

判断题

土壤层实际上是风化的残积物，只不过其中有腐殖质的加入，适宜植物生长。

填空题

Some consumer researchers distinguish (1) "rational" motives and "emotional" (or "non-rational") motives. They use the term "rationality" (2) the traditional economic sense that assumes (3) consumers behave rationally when they carefully consider all alternatives (4) choose those that give them the greatest utility (i.e., satisfaction). (5) a marketing context, the term "rationality" implies that the consumer selects goods based (6) totally objective criteria, such (7) size, weight, price, and so on. "Emotional" motives imply the selection of goods (8) to personal or subjective criteria—the desire (9) individuality, pride, fear, affection or status.
The assumption underlying this distinction is (10) subjective or emotional criteria do not maximize utility or satisfaction. (11) , it is reasonable to assume that consumers always attempt to select alternatives that, (12) their view, serve to maximize satisfaction. Obviously, the assessment of satisfaction is a very personal process, based (13) the individual’s own needs as (14) as on past behavioral, social, and learning experiences. What may appear (15) irrational to an outside observer may be perfectly rational (16) the context of the consumer’s own psychological field. For example, a product purchased to enhance one’s self-image (such as a fragrance) is a perfectly rational form of consumer behavior. (17) behavior did not appear rational to the person who undertakes it (18) the time that it is undertaken, obviously he or she would not do it. (19) the distinction between rational and emotional motives does not appear to be warranted.
Some researchers go so far (20) to suggest that emphasis (21) "needs" obscures the rational, or conscious, nature of most consumer motivation. They claim that consumers act consciously (22) maximize their gains and minimize their losses; that they act not (23) subconscious drives but from rational preferences, (24) what they perceive to be (25) their own best interests.