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乙酸正丁酯合成中无机盐催化作用的研究 总被引：9，自引：0，他引：9
考察了CuSO4·5H2 O、FeSO4· 7H2 O、ZnSO4·7H2 O、CuCl2 ·2H2 O、FeCl3·6H2 O五种无机盐作乙酸与正丁醇酯化反应的催化剂的催化性能 ,结果表明FeCl3·6H2 O是较好的催化剂。同时 ,研究了以FeCl3·6H2 O为催化剂合成乙酸正丁酯的最佳反应条件 ,通过正交实验 ,选定的优化条件为 :催化剂用量为反应物总质量的 3% ,回流分水时间 2h ,酸醇摩尔比 :1 1 2 ,反应温度为回流温度。在最佳条件下 ,酯转化率达 98 98%。 相似文献
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笔者批阅《 2000年全国初中生化学素质和实验能力竞赛试题》时,发现 29题的原标准答案有误,后翻阅了 100多份试卷,有 50％以上的试卷中都出现了与原标准答案类似的错误。 29题是： 20克 CuO溶于 140克温热的 20％ H2SO4溶液,冷却到 20℃时能从溶液中析出多少克 CuSO4· 5H2O晶体 ?(20℃时 CuSO4的溶解度为 20 7克 /100克水 ) 原标准答案是： CuO＋ H2SO4=CuSO4＋ H2O 80 160 20克 x x=40(克 ) 溶液质量为： 20克＋ 140克 =160克 20℃饱和溶液中 CuSO4的质量分数为： CuSO4· 5H2O晶体中 CuSO4的质量分数为： 设 2… 相似文献
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例1 实验室里需要配制480mL 0.1mol.L—1的CuSO4·5H2O溶液,至少需要CuSO4·5H2O__克。错解 0.48L×0.1mol·L-1×250g·mol-1=12.0g。分析容量瓶不能配制任意体积的一定物质的量浓度的溶液。这是因为在配制的过程中是用容量瓶来定容的,而容量瓶的规格又是有限的,常用的有50mL、 相似文献
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镍与HEDP配位化合物的制备及红外光谱表征 总被引：1，自引：1，他引：0
制备Ni(Ⅱ)-HEDP的系列固体配位化合物,用元素分析确定其组成,分别为Ni2L·6H2O、NiH2L·4H2O、NaNiHL·5H2O、K2NiL·8H2O、K2Ni(H2L)2·8H2O、K4Ni(HL)2·12H2O和K6NiL2·10H2O,其中L=CH3C(OH)(PO3)2,用红外光谱进行了表征. 相似文献
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氨浸法制取饲料级硫酸铜 总被引：3，自引：0，他引：3
本工艺以氨水浸取原料中CuO形式的铜。有较高的浸出率。CuO的浸出率达 90 %以上。通过蒸氨将 [Cu(NH3) 4] 2 +转化为CuO ,将CuO溶于稀H2 SO4 母液 ,结晶后可生产出符合国家标准的饲料级CuSO4 ·5H2 O产品。 相似文献
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本文通过大量试验对测定蔬菜中铅含量的三种前处理方法———HNO3-HClO4消化法、H2 SO4 H2 O2 消化法、微波干灰化HNO3 HClO4法进行比较研究 ,证明微波干灰化HNO3-HClO4法具有氧化完全 ,药品用量少 ,无污染等优点。 相似文献
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采用湿式浸渍法将MnSO4·H2O,FeSO4·7H2O,CuSO4·5H2O中的金属分次负载在陶瓷粉末表面,制备以陶瓷为载体的负载型光催化剂,用制备的光催化剂对预处理后的水性油墨废水进行光催化降解作用实验,讨论了光催化剂用量、焙烧温度、不同pH值和强氧化剂等条件对水性油墨废水降解效果。结果表明：在500℃下焙烧后的光催化剂用量为20g/L时,对pH=8-9的水性油墨废水（初始COD为4500-4600mg/L）降解效果明显,并且发现其重复使用10次左右,对水性油墨废水仍有较高的去除率。 相似文献
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采用微波辐射技术,以内桂酸和苄醇为原料,在硫酸氢钠(NaHSO4·5H2O)催化下合成了肉桂酸苄酯.最佳反应条件微波辐射功率为464W,辐射时间为4 min,醇酸摩尔比为111,催化剂用量为0.2 g,酯化率为97%. 相似文献
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硫酸铜晶体结晶水含量的测定实验的改进 总被引：2，自引：0，他引：2
硫酸铜里的铜离子Cu^2＋有空轨道,每个Cu^2＋可以跟四个水分子形成配位键,这就是我们熟悉的水合铜离子[Cu（H2O）4]^2＋,另外,每个离子还可与一个水分子里的H原子形成氢键。所以,硫酸铜晶体的化学式可写为[Cu（H2O）4]SO4·H2O,习惯上简写为CuSO4·5H2O,其中五个分子的结合方式是有所不同的。 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 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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《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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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 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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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献