混合酚类在水中的相行为

研究了50℃和46℃时,苯酚和对苯二酚在水中的相行为,它们明显不同于苯酚-对苯二酚在异丙醚中的情形。混合酚类在水中的溶解度大于各个酚单独在水中的溶解度,而酚类与水的两相共存区域则显著被压缩在较小区域,当对苯二酚百分浓度超过3．2％时,混合酚类完全混溶于水中。另一方面,混合酚类在水中完全混溶区域显著扩张,对苯二酚最大质量百分浓度可达25．8％．     

折光率法测定对苯二酚在若干溶剂中不同温度下的浓度及饱和溶解度

用折光率法测定了45℃、52℃、60℃三种温度下,对苯二酚在乙醇、正丁醇、正戊醇、异丙醚中浓度与折光率的关系以及饱和溶解度。首先进行了实验方法可靠性的验证,试验表明回收率在94.5%-102.4%之间,因而方法的可信度较高。最大溶解度平衡时间的测量表明:对于不饱和体系,振荡2小时,静置0.5小时,误差已小于0.1%;对于饱和溶解度,则必须振荡6-9小时,才能达到最大溶解度,这时误差小于0.02%。工作曲线表明,在这些溶剂中,对苯二酚的溶解度可大到接近23%,其折光率与浓度关系是一条较好的直线。与同一溶剂的苯酚工作曲线相比,相同浓度时对苯二酚的折射率较大,但相差不是很大,因而用平均工作曲线可以测量混合酚类的浓度,误差不大于2%。对于在线估计混合酚类的浓度,这是一个快速而有意义的方法。如果利用气相色谱估计得到对苯二酚与苯酚的比例,则利用内插工作曲线,用本方法测定的混合酚类的浓度误差可小到0.1%。对苯二酚在几种溶剂中的饱和溶解度是有用的热力学数据,尚未见过何处公开发表。     

水-异丙醚-苯酚三元系46℃等温截面相图的实验测定

用气相色谱法实验测定了水—异丙醚—苯酚的三元系在46℃的等温截面相图。柯图上呈现两个两相共存区域和一个单相区域。在46℃水和异丙醚存在两相，当逐渐溶入苯酚后，水富端很小，而醚相中异丙醚摩尔分数逐渐减小到25．4％，苯酚逐渐增加到29．0％，这表明在醚相中苯酚可达到较大溶解度。在46℃水和苯酚也存在两相，在三元系中异丙醚在水相和苯酚相中的溶解度都不大。该相图为工业上萃取提供了一定的基础工作。     

有关苯酚实验的几个问题

1苯酚的溶解度大小问题人教社《化学》教材上说苯酚“在水中的溶解度不大,当温度高于℃时,则能与水混溶。”这句话让许多人误认为苯酚在常温时在水中的溶解度很小微溶或难溶,由此导致《化学》教材和有关资料上的相关题目的参考答案的错误。据《化学用表》知,在℃时,苯酚的溶解度为,属可溶物质,温度稍高,则变成了易溶物质。也就是说,教材中的苯酚“在水中的溶解度不大”并不是说苯酚的溶解度很小,而是相对于“温度高于℃时,则能与水混溶”而言的。有关的洗涤问题“盛放过苯酚的试管可以用酒精进行清洗”,“苯酚有毒,浓溶液沾到皮肤上,应立即…     

折光率法测定苯酚-正庚烷相图和苯酚在若干溶剂中的浓度

发展了一种快速测量中等浓度苯酚的简明方法,对于在线检测具有一定实用意义。用折光率法测定了常压下45℃到60℃间苯酚在无水乙醇、正戊醇、氯仿、四氯化碳、正庚烷中的浓度和苯酚-正庚烷的部分相图。首先进行了方法可靠性和精密度验证。对环己烷-甲醇体系,进行了平衡时间与折光率测量,得出振荡2小时,静止1小时,折光率趋于稳定,误差小于0.05%,从而确定本装置下实验条件为恒温振荡2小时、静止1小时。我们对苯酚-正戊醇体系进行了回收率实验,实验表明回收率可达98.36%。测得45℃、52℃、60℃下的各组工作曲线,曲线表明折光率与溶质浓度在15%以下可用直线近似,在大浓度范围偏离线性关系。因此,在15%以下,可用线性关系求得溶质浓度,超过这一范围,必须用实测工作曲线,才能减少误差。从曲线的等间隔可以看出:同一浓度下,在小温度范围内,线性关系成立。作为实例,我们研究了苯酚-正庚烷体系,这是一个两相体系。首先测定了苯酚-正庚烷体系在两个单相区域的工作曲线。在15%浓度范围内都是一条直线,但它们的斜率竟差4倍。由不同温度下的工作曲线,得到了苯酚-正庚烷体系的部分相图。实验表明,用本方法测量中等浓度苯酚是一种简明、快速而有相当正确度的实用方法。     

高效液相色谱-荧光法测定水中的苯酚及苯二酚残留量

建立了水中苯酚、邻苯二酚、间苯二酚、对苯二酚的高效液相色谱-荧光分析方法。样品过0．45μm滤膜后直接进样,以甲醇-水（体积比30：70）为流动相经反相色谱柱分离后．采用荧光检测器检测。通过时间分组改变检测器的激发和发射波长,从而实现同时检测苯酚、邻苯二酚、间苯二酚、对苯二酚。外标法定量。空白样品及其添加实验结果表明．特征激发和发射波长基线稳定,无基质干扰,结合保留时间可实现准确的定性定量。苯酚、邻苯二酚、间苯二酚的方法检出限为5μg／L（S／N=3）,对苯二酚的方法检出限为10μg／L（S／N=3）。空白样本添加水平在10-50μg／L时,平均回收率为83．5％-93．6％,相对偏差（n=6）为4．3％～7．3％。     

羟丙基-β-环糊精对甲砜霉素包合作用的研究

目的：研究羟丙基-β-环糊精在水溶液中对甲砜霉素的包合作用。方法：采用相溶解度法考察甲砜霉素与羟丙基-β-环糊精在水溶液中包合作用、包合比及包合过程中的热力学参数变化。结果：在不同温度（25℃、35℃、45℃）下，甲砜霉素的溶解度均随羟丙基-β-环糊精溶液浓度的增加而呈线性增加，相溶解度图为AL型。结论：在上述研究条件下，甲砜霉素与羟丙基-β-环糊精可自发地形成摩尔比1：1的包合物。     

注意与苯酚相关的几个实验现象

现象一:苯酚的水溶性现象由于常温下苯酚为无色的晶体,且温度低于70℃时苯酚在水中的溶解度不大,因而很容易错误地认为:过量的苯酚溶于水会出现沉淀现象。事实上,过量的苯酚溶于水不会出现沉淀现象,出现的是水与油状苯酚的分层现象,其中水在上层,液态苯酚在下层。     

苯酚教学中的几个问题

一、关于苯酚在水中的溶解性1.苯酚在水中的溶解性表述不一文献名对苯酚的溶解性表述《高中化学》第二册常温下苯酚在水中的溶解性不大。顾翼东主编《化学词典》491页( 1989年版) 在室温下稍溶于水。王箴编《化工辞典》3 6页( 2 0 0 2年第四版) 室温时稍溶于水。B .N .库茨涅佐夫著《化学试剂与制剂》手册64 9页在10 0g水中15℃时的溶解度为8.2 g。齐齐巴宾著《有机化学基本原理》2 84页在水中的溶解度达8%。曾昭琼主编《有机化学》上册2 94页苯酚微溶于水,2 5℃时溶解度为8g。《高中化学教学参考》甲种本第三册2 5 3页往水中加入少量苯酚,…     

有关苯酚实验的几个问题

人教社《化学》教材上说苯酚“在水中的溶解度不大，当温度高于65℃时，则能与水混溶。”这句话让许多人误认为苯酚在常温时在水中的溶解度很小(微溶或难溶)，由此导致《化学》教材和有关资料上的相关题目的参考答案的错误。据《化学用表》知，在15℃时，苯酚的溶解度为8．2g，属可溶物质，温度稍高，则变成了易溶物质。也就是说，     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

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?     

Western and Eastern culture differences in commercial field

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.     

只要努力,不要后悔

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.     

浅谈移民问题

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.     

Sister Carrie, an Adherent of Desires

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.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

风的曲线

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.