问题 不定项选择

与其他灭火系统相比较,气体灭火系统的优点主要有()。

A、化学稳定性高,腐蚀性小

B、电绝缘性能好,可用于扑救电气火灾

C、灭火速度快,空间淹没性能好

D、灭火剂造价低

答案

参考答案:A, B, C

问答题

下面是两位初中化学教师讲授“物质的变化和性质”的教学实施记录,阅读后回答问题。

[张老师的教学实施记录][社会引入]观看准备好的视频——生活中的几种物质及其变化,如钢铁制品生锈、冰雪融化成冰、原子弹的爆炸现象。

[演示实验及学生实验]四个实验——实验1水的沸腾;实验2胆矾的研碎;研碎前后胆矾的溶解,胆矾溶液与氢氧化钠溶液的反应;实验3石灰石与稀盐酸的反应,实验4二氧化碳通入到澄清石灰水。其中实验1有师生共同完成,实验2和实验4的反应由学生分组完成,其余实验由教师演示实验。教师引导学生由实验3得到两个结论:实验2中的粉末是胆矾:胆矾与氢氧化钠溶液反应生成的蓝色物质是新生成的物质。[提问]比较归纳上述四个实验的相同点和不同点。

[学生讨论并交流]略[提问]教师列举两个变化,由学生判断是物理变化还是化学变化?为什么?

[学生举例]说明生活中的物理变化和化学变化。

[提问]在物理变化和化学变化中还伴随着哪些现象?举例说明。

[学生讨论]略。[提问]酒精易挥发、铁易生锈在本质上有什么不同?谁还能举出一些相似的例子?

[学生讨论并派代表回答]举出类似的例子。并总结归纳出物理性质和化学性质。

[提问]老师举出两个性质,由学生判断是物理性质还是化学性质,为什么?

[讲解]老师对有关物理性质方面的几个基本概念做简单介绍(熔点、沸点、密度)。引导学生观察一瓶氧气和一瓶一氧化碳,讨论结合自己的生活实际经验和知识,尽可能地描述氧气和二氧化碳的性质,试着判断哪些属于物理性质?哪些属于化学性质?利用哪些方法可以进行判断,并与周围同学进行相互讨论和学习。

[讲解]说明物理性质、化学性质与物理变化、化学变化之间的联系,说明事物的变化是复杂的,对复杂事情的分离是科学的研究方法之一。[李老师的教学实施记录][直接引入]整个自然界是由各种各样的物质构成,自然界中的物质处于不断的变化之中。(结合新学期的一些变化进行举例,使学生感到熟悉,活跃课堂气氛)

[师生交流回答]老师:自然界有哪些变化?学生:下雨、木材燃烧、植物的光合作用、瀑布下落。老师:若将以上四个变化进行分类,你准备怎么分?分类的标准是什么?学生:根据变化中是否有新的物质生成,确定上述四个变化分为物理变化和化学变化。

[小结]下雨和瀑布下落没有新的物质生成,这类变化叫作物理变化;木材燃烧生成新的物质二氧化碳,植物的光合作用制造了氧气和有机物,在变化中生成了新的物质,判断这一类变化属于化学变化。

[演示PPT]演示水分子电解的动画。请同学从微观的角度判断水的电解是物理变化还是化学变化?[得出结论]化学变化的实质是构成物质分子的原子重新组合,形成新的分子。

[过渡]我们周围的物质在不断地发生变化,如何判断物质的变化是否发生了?要了解物质的变化,必须通过观察和实验寻找物质变化的证据。

[演示实验]取适量的硝酸铅溶液放入锥形瓶中,再向锥形瓶中加入适量的碘化钾溶液,观察反应前后的实验现象,并分析实验现象:在此反应中,有不溶于水的新物质生成,是化学变化。拿出一段铁丝,观察颜色、状态、形状,弯曲成各种形状,并用剪刀把铁丝剪成几段。

[讲述]每种物质都有自己的性质和特征,不同的物质有不同的性质和特征,根据物质的某种性质,对某种物质进行识别和判定,我们可以把物质的性质分为两类:物理性质和化学性质。

[小结]通过上述实验我们可以发现物质的颜色、形状和状态、是否有沉淀生成等都可以作为判别物质变化的标准。

[演示实验]观察硫酸铜晶体的变化。实验1硫酸铜晶体溶于水;实验2硫酸铜溶液中加氢氧化钠;实验3硫酸铜晶体加热:实验4加热后的硫酸铜粉末加水。

[得出结论]硫酸铜的物理性质——能溶于水的蓝色的固体;化学性质——与氢氧化钠反应生成蓝色的氢氧化铜沉淀。

[小结]要想知道某一物质是什么物质、会发生什么样的变化;我们可以通过观察、实验的方法,从物质的形态、颜色、温度,变化中有无沉淀生成、气体生成方面寻找证据,对各种证据进行分析,从而认识物质的变化和变化规律,推测它们的性质,并利用物质变化规律造福人类。请结合两位老师的教学实施记录,回答下述问题:

(1)比较两位老师的教学内容的异同。

(2)这两位老师的化学教学内容组织采用了哪种形式?

(3)判断这两位老师的教学方案是否体现了科学的探究思想,为什么?

(4)这两位老师是否灵活运用多样化的教学方式和手段?并进行说明。

(5)试说明两位老师是如何创设学习情境,激发学生的学习兴趣?

单项选择题

The most thoroughly studied intellectuals in the history of the New World are the ministers and political leaders of seventeenth-century New England. According to the standard history of American philosophy, nowhere else in colonial America was “so much importance attached to intellectual pursuits.” According to many books and articles, New England’s leaders established the basic themes and preoccupations of an unfolding, dominant Puritan tradition in American intellectual life.

To take this approach to the New Englanders normally means to start with the Puritans’ theological innovations and their distinctive ideas about the church—important subjects that we may not neglect. But in keeping with our examination of southern intellectual life, we may consider the original Puritans as carriers of European culture, adjusting to New World circumstances. The New England colonies were the scenes of important episodes in the pursuit of widely understood ideals of civility and virtuosity.

The early settlers of Massachusetts Bay included men of impressive education and influence in England. Besides the ninety or so learned ministers who came to Massachusetts churches in the decade after 1629, there were political leaders like John Winthrop, an educated gentleman, lawyer, and official of the Crown before he journeyed to Boston. These men wrote and published extensively, reaching both New World and Old World audiences, and giving New England an atmosphere of intellectual earnestness.

We should not forget, however, that most New Englanders were less well educated. While few crafts men or farmers, let alone dependents and servants, left literary compositions to be analyzed, it is obvious that their views were less fully intellectualized. Their thinking often had a traditional superstitious quality. A tailor named John Dane, who emigrated in the late 1630s, left an account of his reasons for leaving England that is filled with signs. Sexual confusion, economic frustrations, and religious hope—all came together in a decisive moment when he opened the Bible, told bas father that the first line he saw would settle his fate, and read the magical words: "Come out from among them, touch no unclean thing, and I will be your God and you shall be my people." One wonders what Dane thought of the careful sermons explaining the Bible that he heard in Puritan churches.

Meanwhile, many settlers had slighter religious commitments than Dane’s, as one clergyman learned in confronting folk along the coast who mocked that they had not come to the New World fur religion. "Our main end was to catch fish.

The story of John Dane shows that less well-educated New Englanders were often ()

A. influenced by superstitions

B. troubled with religious beliefs

C. puzzled by church sermons

D. frustrated with family earnings