共查询到20条相似文献，搜索用时 78 毫秒
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物质的溶解过程是一复杂的化学过程,物质溶解平衡是中学化学平衡中常见的化学平衡.物质的溶解度反映了物质的溶解性能.让学生动手进行物质溶解度的测定,不仅能够激发学生的学习兴趣,而且能够帮助学生掌握溶解平衡.对于溶解度大的物质,饱和溶液中浓度较大可以通过滴定等方法测出溶解度.但对于难溶电解质,由于饱和溶液浓度较小,通过滴定方法很难测定其溶解度. 相似文献
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从固体物质的溶解度曲线可以获得很多信息,如某一物质在某一温度下的溶解度;同一物质在不同温度时的溶解度;不同物质在同一温度时的溶解度;不同物质的溶解度受温度变化影响的大小.为了考查学生的分析能力,在2007年各地中考化学中出现了许多与溶解度曲线相关的试题,现归纳如下,以供参考. 相似文献
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一、意义溶解度曲线的意义可概括为“两点”、“一线”、“两面” .1.两点(1)溶解度曲线上的点 ,表示某温度下某物质的溶解度 .(2 )两条或几条溶解度曲线的交点 ,表示在该温度下 ,几种物质的溶解度相同 .2 .一线溶解度曲线 ,表示某物质的溶解度随温度变化情况 .曲线的“坡度”表明温度对某物质溶解度的影响程度 :“坡度”越大 ,温度对溶解度影响越大 ;反之越小 .3.两面(1)溶解度曲线下面平面上的点 ,表示该温度下溶液没有达到饱和 .(2 )溶解度曲线上面平面上的点 ,表示该温度下溶液为饱和溶液 ,且有晶体析出 .二、应用1.根据溶解度曲线 ,结… 相似文献
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在直角坐标系中 ,以纵坐标表示溶解度 ,横坐标表示温度 ,将某物质在不同温度下溶解度的点连成一条光滑的曲线 ,这条曲线叫做该物质的溶解度曲线 (如图 1 ) .它反映了物质溶解度随温度变化的情况 .一、意义图 11 溶解度曲线上的每一点 ,表示某温度下某物质的溶解度 ,同时也表示所对应的溶液是该温度下的饱和溶液 .如图 1中 ,Ｍ点表示物质Ａ在ｔ1℃时的溶解度是Ｓ1ｇ;Ｑ点则表示物质Ａ在ｔ2 ℃时的溶解度为Ｓ2 ｇ .同时Ｍ点也表示在ｔ1℃时 1 0 0ｇ水溶解了Ｓ1ｇ物质Ａ ,所得溶液便达到饱和 .此时 ,溶液中溶质和溶剂质量之比等于该温度下Ａ的… 相似文献
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袁惠英 《华南师范大学学报(社会科学版)》1973,(6)
三、有关溶解度的计算物质溶解性的大小用溶解度来表示.在一定温度下,某物质在100克溶剂里达到饱和所溶解的克数,叫做这种物质在这溶剂里的溶解度.如果不指出溶剂,通常所说的溶解度就是物质在水里的溶解度.在一定温度下,不能再溶解同种溶质的溶液叫做这种溶质的饱和溶液.要明确,在数值上,溶解度是指100克溶剂能够溶解溶质的最大量(以克表示).这时组成的溶液,一定是该温度下的饱和溶液.例如在20℃时,食盐的溶解度是35.9克,就是说,在20℃时,100克水最多能溶解食盐35.9克.这时便组成(100+35.9)克食盐饱和溶液.所以,进行有关溶解度问题的计算,必须对溶解度和饱和溶液的概念有透彻的理解. 相似文献
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溶解度曲线是表示物质的溶解度随温度(或压强)改变而变化的曲线,反映的是物质溶解度和温度(或压强)的关系,以温度为横坐标,溶解度为纵坐标绘制的曲线。现以固体物质的溶解度曲线为例,叙述其涵义并摘录了近年来有关溶解度曲线的典型试题,希望能对同学们有所启发。一、溶解度曲线的涵义1.点的涵义①曲线上任意一点表示对应温度下某物质的溶解 相似文献
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王军文 《中学生数理化(高中版)》2010,(5)
七、对物质的溶解度规律把握不准易错分析:物质的溶解度变化规律,主要有三类:(1)温度升高,溶解度增大,如氯化钾、硝酸钾等.(2)温度升高,溶解度增大,但是增加的程度小,如氯化钠.(3)温度升高,溶解度减小,如气体、氢氧化钙等.有些同学对气体的溶解度与温度的关系把握不 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
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陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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YANGShiguo 《重庆大学学报(英文版)》2004,3(1):86-88
The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex. 相似文献