SO2通入FeCl3溶液的实验探究

在讲二氧化硫化学性质时,为了说明二氧化硫的还原性,笔者补充了一个实验：把二氧化硫气体通人FeCl3溶液中,观察FeCl3溶液变成浅绿色,证明二氧化硫的还原性．可是事与愿违,把二氧化硫气体通入FeCl3溶液后,不但没有看到溶液变成浅绿色,反而加深变成红褐色．这种异常现象使笔者大为吃惊,于是我们师生在课下到实验室进行了探究．     

SO2与品红溶液的反应是可逆反应

1 实验(实验时的室温为9℃) 实验1:将SO2通入品红溶液至品红褪色,然后用酒精灯加热至无色溶液刚好变红.放置一段时间(冷却)后红色自动消失,再加热至刚好变红,放置一段时间后红色又自动消失.若将褪色的品红溶液持续加热较长的时间,则品红的红色不会在冷却后再褪色.     

SO2与品红溶液的反应是可逆反应

1　实验 (实验时的室温为 9℃ )实验 1 :将SO2 通入品红溶液至品红褪色 ,然后用酒精灯加热至无色溶液刚好变红。放置一段时间 (冷却 )后红色自动消失 ,再加热至刚好变红 ,放置一段时间后红色又自动消失。若将褪色的品红溶液持续加热较长的时间 ,则品红的红色不会在冷却后再褪色。实验 2 :将SO2 通入品红溶液至品红褪色 ,敞开放置于通风橱内 ,5天后试管内开始变微红 (室温低、反应慢、反应时间较长 )。实验 3:将SO2 通入品红溶液至品红褪色 ,再加一些盐酸 ,敞开放置于通风橱内 ,两天后试管内开始变微红。实验 4 :用 50ml的大注射器抽取实…     

关于SO2使品红溶液褪色的实验改进

HCIO,O3,H2O2,Na2O2及SO2都具有漂白性,但SO2的漂白性是一个可逆的过程,即SO2使品红溶液褪色,而漂白后在一定的时间或加热的情况下是可以恢复到原来的颜色的.原理是SO2与这些有色物质生成的无色物质不稳定,容易分解.为了证明SO2的这个特性,教材中的实验是把SO2通入盛有品红溶液的试管中,先观察其溶液褪色,后又在酒精灯上加热使其分解恢复为原来的颜色.     

SO2通入Ba(NO3)2溶液中反应原理的实验研究

SO2气体通入Ba(NO3)2溶液中会产生沉淀,其原因是氧气和硝酸根的氧化作用,人们一般认为反应中硝酸根氧化亚硫酸根的能力更强,是产生沉淀的主导因素.本文通过对比实验,利用pH传感器,得到不同反应条件下溶液的pH变化曲线,分析曲线得知在该反应中氧气和硝酸根都能够氧化亚硫酸根,但是氧气氧化能力更强.     

SO_2气体通入BaCl_2溶液实验的探究

针对苏教版《化学1》中＂二氧化硫水溶液中滴加氯化钡溶液再滴加过氧化氢溶液＂探究实验的不足,巧妙地设计了在无氧氛围中把SO2气体通入BaCl2溶液中,然后再滴加双氧水,取得了非常明显的效果。     

CO2通入Na2CO3溶液的实验研究

CO2 通入Na2 CO3溶液会有NaHCO3沉淀析出吗 ?这是一个问者容易答者难的问题。问者何易呢 ?第一、Na2 CO3溶液显碱性 ,CO2 是微溶于水的酸性气体 ,两者相遇肯定会有NaHCO3生成。第二 ,饱和CO2 水溶液 ,其浓度约为 0 .0 1mol·L- 1 ,pH =3.98;0 .1mol·L- 1 Na2 CO3,c(OH- ) =4.2 2× 1 0 - 3mol·L- 1 ,pH =1 1 .6[即使是Na2 CO3 浓溶液 ,c (Na2 CO3) =1 .32mol·L- 1 ( 1 4% ) ,pH =1 1 .76]两者相遇 ,无疑会发生酸碱反应 ,生成NaHCO3。第三 ,从溶解性考虑 :Na2 CO3 的溶解度( 2 0℃ ,2 1 5 g)。NaHCO3的溶解度 ( 2 0…     

CO2通入饱和Na2CO3溶液的实证分析

把CO2通入饱和Na2CO3溶液有没有白色NaH-CO3沉淀析出,对于这个问题,有两种截然不同的观点. 　　一种意见认为:理论上Na2CO3溶液是个碱,有资料显示:C(Na2CO3)=1.32mol/L,14%,Ph=11.76(更不用说是饱和Na2CO3溶液了:20℃时,17.7%;25℃时25%);通常室温时,H2CO3饱和溶液浓度C(H2CO3)=0.04mol/L,Ph=3.88.当CO2持续通入Na2CO3饱和溶液时,生成溶解度比Na2CO3要小得多的NaHCO3是理所当然的(NaHCO3 20℃时9.6g/100g水,25℃时10.35g/100g水;Na2CO3 20℃时21.5g/100g水,30℃时38.8g/100g水).……     

CO_2通入饱和Na_2CO_3溶液的实证分析

把CO2 通入饱和Na2 CO3溶液有没有白色NaH CO3沉淀析出 ,对于这个问题 ,有两种截然不同的观点。一种意见认为 :理论上Na2 CO3溶液是个碱 ,有资料显示 :C(Na2 CO3) =1.32mol/L ,14 % ,pH =11.76(更不用说是饱和Na2 CO3溶液了 :2 0℃时 ,17.7% ;2 5℃时 2 5 % ) ;通常室温时 ,H2 CO3饱和溶液浓度C(H2 CO3) =0 .0 4mol/L ,pH =3.88。当CO2 持续通入Na2 CO3饱和溶液时 ,生成溶解度比Na2 CO3要小得多的NaHCO3是理所当然的 (NaHCO32 0℃时 9.6g/10 0g水 ,2 5℃时 10 .35g/ 10 0g水 ;Na2 CO32 0℃时 2 1.5g/ 10 0g水 ,30℃时 3…     

氯化钴溶液变色原理的探究

苏教版<实验化学>(2009年6月修订版)第55页"氯化钴溶液的变色原理"中安排了如下实验探究浓度对化学平衡的影响.     

探究二氧化硫对葫芦科两种植物的影响

二氧化硫是一种有毒的气体。当二氧化硫在大气中的含量超过一定的浓度时,植物就会受到影响。为了观察二氧化硫对葫芦科植物生长的影响,在实验室里利用亚硫酸钠与稀硫酸反应生成二氧化硫,并用浓度为0.014mg/L和0.028mg/L的二氧化硫分别对长势相同的南瓜幼苗和黄瓜幼苗进行刺激,观察并记录了二氧化硫对植物的影响情况,发现这两种植物受害的程度与植物的种类、叶片的叶龄及二氧化硫的浓度有关。当二氧化硫浓度相同时,在一定时间范围内,南瓜幼苗受害的程度比黄瓜幼苗严重;同一植株不同叶片受害程度也有所不同,其受害程度的先后顺序是:成熟叶、老叶、幼叶。当二氧化硫浓度不同时,同种植物的受害程度也有所不同,浓度越大,其受害程度越严重。     

二氧化钛薄膜光催化降解酸性品红

采用溶胶－凝胶法在玻璃表面制得TiO2(锐钛型）薄膜，研究了以254nm的紫外线为光源，酸性品红（AF）在TiO2薄膜上的光催化降解初始速率与溶液初始浓度、初始pH值及外加氧化剂H2O2的关系。结果表明，AF的光催化降解行为采用Langmuir-Hinshelwood(L-H)模型来解释，利用TiO2薄膜作为光催化剂光降有机物AF具有较好的应用前景。     

《红楼梦》中表红色调颜色词研究

《红楼梦》是我国四大名著之一,其中的词汇更是非常丰富的一项资源。在本文中,将就《红楼梦》中表红色调颜色词进行一定的研究。     

用高等植物监测大气中的二氧化硫

通过测定天津常见高等植物树种白杨、垂柳的树皮中的pH值,研究大气中SO2的含量对树木pH值的影响。结果表明,大气中污染对植物pH值影响较大。树皮pH值与大气酸性污染物含量呈显著的负相关。     

Exploring dimensions of change: the case of MOOC conceptions

This paper addresses a relatively new phenomenon in higher education, Massive Open Online Courses (MOOCs), and explores conceptions around this new and emerging development from the perspective of a number of stakeholders in the university. A phenomenographic approach is adopted. The study explores how different stakeholders at a university perceive the MOOC phenomenon, and reflects on how the many conceptions stakeholders adhere to are made meaningful for academic developers in their role as ‘partners in arms’. The conceptions run across a continuum from the local and narrow to the global and broad. The study identifies challenges to change agency in a higher education institution.     

氯水中微粒成分的探究

"那么,我们到底能否用实验证明氯水中含有H+?"笔者用低沉的、沙哑的声音向高一(3)班学生发问.2002年12月11日上午第三节课,地点化学实验室,笔者运用探究式教学方法尝试研究氯气与水的反应,并正在努力激发学生积极参与探究的热情.     

Exploring the parallelism between change in students' conceptions and historical change in the concept of inertia

This study investigates students' conceptions of inertia and compares these conceptions with historical change in the concept. A total of 736 students from four different age groups (i.e., age 11, 13, 15 and 17) participated in the survey. Questions in the questionnaire represent problems related to the concept of inertia which have been argued by past scientists such as Aristotle, Buridan, Galileo, and Newton. The questionnaire contained three questions, each concerned with one of the following applications of inertia: natural motion, the motion of a flying spear, and the falling motion of a stone on a moving ship. The results of the survey showed that there were considerable similarities as well as dissimilarities between students' conceptions and the views of past scientists. It is suggested that this kind of comparison studies would give useful background information on change in students' conceptions. To this day every student of elementary physics has to struggle with the same errors and misconceptions which then had to be overcome, and on a reduced scale, in the teaching of this branch of knowledge in schools, history repeats itself every year. (Dijksterhuis, 1961, p. 30)     

Wilderness therapy intervention with adolescents: Exploring the process of change

This study aimed to understand the process of change within Wilderness Therapy. It used grounded theory to explore development and change during the programme and relate this to theories of adolescence and engagement, particularly for adolescents in the care system.

Data collected from interviews with 11 adolescents were analysed using constructionist grounded theory. The wilderness environment, the staff, and the activities were identified as interactive factors that facilitated personal development. The analysis demonstrated the influence of early engagement in overall change. Relational factors interacted with an appropriate level of support and encouragement during activities which led to the adolescents experiencing success and increases in self-worth, self-esteem and efficacy. Improvements in self-efficacy, social skills, and anger management, as well as increasingly more positive views about the world were demonstrated in all participants who completed the programme.