基准草酸钠标定高锰酸钾标准溶液方法的讨论

对基准草酸钠标定高锰酸钾标准溶液的原方法和实验方法进行对比讨论,目的仅在于配出精准溶液,确保优质分析。

基于二苯胺磺酸钠作指示剂的滴定法测定高锰酸盐指数

高锰酸盐指数是地表水和地下水的常规监测指标,其国内标准早在1989年就已出台,并在环境、水利和疾控等部门开展多年。高锰酸盐指数是个条件性指标,对加热温度和加热时间的要求十分严格,且该指标在测定过程中受空白和反应温度等因素的制约,因此准确度不是很高。

银杏叶中单宁提取工艺的优化研究

银杏(Ginkgo BilobaL.)是一种具有活化石之称的古代二叠纪子遗树种,由于其果、叶、皮等有很高的保健和药用价值,深受国内外学者和企业家的青睐。

关于高锰酸钾法检测生活饮用水耗氧量的几点问题的思考

耗氧量作为生活饮用水卫生标准水质常规检测指标,综合反映了水体被水中还原性物质(包括有机物和无机物)污染的情况。目前,我国生活饮用水中耗氧量的测定与评价按照《生活饮用水卫生标准检验方法》(GB/T5750-2006)和《生活饮用水卫生标准》(GB 5749-2006进行)。根据标准规定,耗氧量的检测需要酸性高锰酸钾滴定法,在实际检测工作中遇到了以下几点问题和疑惑:(1)

专题八 物质纯度的测定

高考动向1.结合具体实验或工业流程对样品中某种特定产品的含量（以质量百分数形式）进行分析计算;2.掌握一些特定物质（如亚硫酸钠、亚铁盐、胆矾结晶水）含量测定的实验方法;3.了解生活中一些典型药物（如补血剂、双氧水等）,并了解对某种成分进行测定的实验技能。考点分析考点1.物质的质量百分数的测定。

Behavior of calcium oxalate in sodium aluminate solutions

The stability of calcium oxalate is critical for the removal of sodium oxalate from sodium aluminate solutions.This studyinvestigated the behavior of calcium oxalate in sodium aluminate solution containing sodium carbonate.Results show that calciumoxalate can be converted to tricalcium aluminate hydrate(TCA)and calcium carbonate in sodium aluminate solution and sodiumcarbonate solution,respectively.Elevating temperature,extending residence time,or increasing caustic soda concentration enhancesthe conversion ratio of calcium oxalate in sodium aluminate solution;as a consequence,anti-causticisation occurs.Stability ofcalcium-containing compounds in sodium aluminate solution containing sodium carbonate differs from that in sodium aluminatesolution or sodium carbonate solution.Na2CO3in aluminate solution accelerates the transformation of calcium oxalate;thus,aluminais lost because of4CaO·Al2O3·CO2·11H2O and TCA formation.Calcium carbonate,4CaO·Al2O3·CO2·11H2O and calcium oxalatecan change into TCA in sodium aluminate solution at elevated temperature.Calcium oxalate remains relatively stable in dilutealuminate solution within a short residence time at low temperature.Thus,a novel process for removal of sodium oxalate by limecausticisation was presented and employed in an alumina refinery in China.

Effect of oxalate on seed precipitation of gibbsite from sodium aluminate solution

The precipitation performance and kinetics of gibbsite from sodium aluminate solution with different sodium oxalate concentrations as well as the corresponding influence mechanism of oxalate during the seed precipitation process were systematically investigated by physicochemical properties test,using SEM and Raman spectra.As the concentration of sodium oxalate increases,both the precipitation rate and particle size of gibbsite decrease.The presence of sodium oxalate not only increases the viscosity of sodium aluminate solution,but also promotes the transformation of Al(OH)4^? to Al2O(OH)6^2?.The overall reaction rate constant decreases and the apparent activation energy of gibbsite increases with the increasing sodium oxalate concentration,the rate controlling step of which is chemical reaction.The needle-like sodium oxalate precipitates on the gibbsite crystals and covers the active Al(OH)3 seed sites,which leads to the lower precipitation rate and the finer particle size of gibbsite during the seed precipitation process.

Reaction kinetics and mechanism of calcium oxide in dilute sodium aluminate solution with oxalate based on lime causticization

The formation kinetics and mechanism of tricalcium aluminate hydrate and calcium oxalate in dilute sodium aluminate solution and sodium oxalate solution were studied respectively based on the lime causticization, and the optimal conditions for removing the oxalate in dilute sodium aluminate solution as well as the mechanism were finally obtained.The formation processes of tricalcium aluminate hydrate and calcium oxalate are mainly controlled by the chemical reaction and the inner diffusion respectively,and the corresponding reaction rate equations as well as the apparent activation energy were calculated. The hydrocalumite with a spatially interleaved structure will form in dilute sodium aluminate solution with sodium oxalate, greatly removing the oxalate impurity by absorption. Calcium oxalate can be converted to tricalcium aluminate hydrate with the increasing reaction time. The oxalate causticization efficiency and the alumina loss rate can be over 90% and below 31% respectively when reacted at 50℃ with a stirring rate of 200 r/min.

对于高锰酸钾消耗量的测定中遇到的问题看法及应对

本文对高锰酸钾消耗量的测定中遇到的众多现实问题进行分析及应对,使实验可以简化为对一个高锰酸钾(c(1/5KMnO_4)=0.1mol/L)标准溶液的标定,掌握和了解了高锰酸钾、草酸、草酸钠物理化学性质,使分析操作灵活,易掌控。

利用家兔做“血液循环器官”一課的实驗

在中学的条件下,家兔无論在課堂或課外活动中,都是重要的实驗对象。在飼养与管理家兔过程中,学生熟悉了管理与飼养动物的一般原理,进行了实驗与观察。在动物課,特別是人体解剖生理学中,应用家兔作剖驗和演示实驗,是极方便的。下面是八年級学习“血液循环器官”一課时,用家兔所进行的实驗。血液凝固的演示实驗目的:树立学生对血液凝固与血液凝固的生物学意义的具体概念。对象与設备:家兔;保險刀片;5块載玻片;“保湿小室”——有玻璃盖上的标本盤或小碟。