比较浓硝酸与稀硝酸氧化性的依据

用电极电位可比较水溶液中氧化剂或还原剂的强弱。在298 I}的标准态下,即气体的压强为101 325 Pa,水溶液中溶质的活度(近似于浓度)为1mol儿时,可用标准电极电位(还原电位)来量度氧化剂的氧化性或还原剂的还原性的强弱。     

碳与浓硝酸反应的补充实验

在全国统编教材高级中学课本化学 (必修 )第一册 (ｐ180 )和全日制普通高级中学教科书 (试验本 )第二册 (Ⅰ ) (ｐ2 6)中均提到碳与浓硝酸能反应 ,以说明浓硝酸具有强氧化性。由于该实验课本没作要求也很难做成功 ,所以教师只能在学习金属与浓硝酸反应性质的基础上运用推理方法让学生认识浓硝酸的这一特性。碳与浓硝酸的反应实验很难做成功的原因经分析 ,我们认为主要有 3点 :一是反应温度达不到要求。由于浓硝酸中含有一定量的水 ,当红热的炭块投入到浓硝酸中时只能发生局部的短暂的反应 ,反应放出的热量不足以维持反应继续进行 ,故炭块不…     

铜与浓硝酸反应的装置设计及现象研究

针对铜与浓硝酸的反应,阐述了实验装置的绿色化设计,通过控制条件使反应溶液呈现绿色和蓝色的变化,并挖掘实验中的化学思想。     

铜与稀、浓硝酸反应演示实验的改进

全日制普通高级中学教科书(试验修订本·选修)第二册第12页,铜与稀、浓硝酸反应的演示实验,在试管中加入硝酸后再用无色塑料袋将试管口罩上并系紧。这期间时间间隙短,气体易外泄而引起污染教室空气,且实验完成后处理袋内的气体过程中仍会造成污染,为此,我们对该实验进行了以下改进。仪器:A、B为相同型号的具支试管和普通试管,C为2 0mL塑料注射器,内装10mL饱和氢氧化钠溶液,D为2 0mL玻璃注射器,内装10mL空气。操作及实验现象:向具支试管中加入1mL～2mL浓硝酸,当红棕色二氧化氮升至将近支管口2cm处时向上将铜丝刚好提离浓硝酸液面,此时,铜…     

铜与浓、稀硝酸反应实验装置的创新设计

通过分析现行苏教版化学教材中铜与浓、稀硝酸反应实验的不足,从教学实际的角度,科学地设计出铜与浓、稀硝酸反应实验方案.该设计将2项实验组合在一起,较好地实现了操作简单、现象对比明显、原料节约、原理展示清晰、绿色环保和有效调控的创新目的.     

铜与浓、稀硝酸反应装置的组合设计

人教版高中化学教科书(试验修订本·必修加选修)中关于铜与硝酸反应的实验装置,我认为有不够科学合理之处.     

对《硝酸与石蕊试液反应本质的质疑》的实证探索

通过一系列实验证明,浓硝酸对石蕊显色反应后的褪色现象,就其反应本质而言仍然是一种氧化还原反应。至于浓硝酸对石蕊发生硝化反应的说法,至今还缺少确凿的事实依据和有公信力的理论支撑。     

硝酸铅沉淀/ICP-MS法测定高纯铅中18种杂质

通过硝酸铅沉淀分离基体铅、有效富集高纯铅中镁、铝、钙、铁、镍、钴、锰、铜、锌、砷、硒、镉、铟、锡、锑、碲、铊、铋等18种杂质,通过电感耦合等离子体质谱测定高纯铅中18种杂质,测定下限在0.04～0.32μg/mL,加标回收率为80%～108%,测定精密度(RSD)为2.5%～14%。     

探讨浓硝酸与铜反应的混合液呈绿色的本质原因

浓硝酸和铜反应的溶液为草绿色,说法较多,还存在疑问。通过大量的实验,认为主要是NO2和水反应生成的亚硝酸,再结合铜离子生成铜的亚硝酸化合物,使溶液呈绿色。     

硝酸铋共沉淀—火焰原子吸收法测定蒸馏酒中痕量铅

蒸馏酒中铅的测定方法,常用消化样品-双硫腙比色法或稀释样品-火焰原子吸收光度法。前者操作复杂,重现性差,且用剧毒药品氰化钾。后者灵敏度不高,不能测定含铅量低的酒样。本文报道了用硝酸铋作共沉淀剂分离富集、火焰原子吸收光度法测定蒸馏酒中痕量铅的方法。该方法操作简便,灵敏度高(95％置信度的检出限为0.005mg·L~(-1)),线性范围宽,基体没有干扰。相对标准偏差为2.2％～4.5％。回收率为100.2％～103.2％。对样品进行测定,结果与双硫腙比色法一致。     

电镀锌—镍合金的影响因素和反应机理

用原子发射光谱和扫描电镜等仪器研究了电镀锌－镍合金过程中诸多因素对镀层组成、性能的影响，探讨了施镀机理并了异常共沉积结论。     

铜与浓、稀硝酸反应的改进实验

使用大试管、胶头滴管、Y形导管等改进了铜与浓、稀硝酸的反应实验,在完全密闭条件下进行,操作简单,现象明显,尾气处理方便安全,零污染。     

硝酸氧解法提高泥炭中黄腐酸的产率

硝酸氧解法提高泥炭中黄腐酸的产率;腐植酸;硝酸氧化降解     

对2个涉及炭与浓硝酸反应问题的探讨

从实验与理论的角度, 对涉及炭与浓硝酸反应的2个问题进行探讨, 结果表明: (1)常温下氯离子对炭与浓硝酸的反应未见明显加速作用, 但自身会被浓硝酸氧化;(2)炭与浓硝酸反应的主要氧化产物是CO2, CO虽有生成但含量较低。     

Carbon Nanostructures Derived through Hypergolic Reaction of Conductive Polymers with Fuming Nitric Acid at Ambient Conditions

Hypergolic systems rely on organic fuel and a powerful oxidizer that spontaneously ignites upon contact without any external ignition source. Although their main utilization pertains to rocket fuels and propellants, it is only recently that hypergolics has been established from our group as a new general method for the synthesis of different morphologies of carbon nanostructures depending on the hypergolic pair (organic fuel-oxidizer). In search of new pairs, the hypergolic mixture described here contains polyaniline as the organic source of carbon and fuming nitric acid as strong oxidizer. Specifically, the two reagents react rapidly and spontaneously upon contact at ambient conditions to afford carbon nanosheets. Further liquid-phase exfoliation of the nanosheets in dimethylformamide results in dispersed single layers exhibiting strong Tyndall effect. The method can be extended to other conductive polymers, such as polythiophene and polypyrrole, leading to the formation of different type carbon nanostructures (e.g., photolumincent carbon dots). Apart from being a new synthesis pathway towards carbon nanomaterials and a new type of reaction for conductive polymers, the present hypergolic pairs also provide a novel set of rocket bipropellants based on conductive polymers.     

The Application of Gibberellic Acid to the Determination of Trace Amounts of Lead by Spectrofluorimetry

The ionization constant of fluorescent reagent gibberellic acid (GA) was established spectrophotometrically. The fluorescent reaction of this reagent with lead was studied. Based on this chelation reaction, a sensitive, direct spectrofluorimetric method for the determination of trace lead with use of GA has been developed. The reaction conditions for the fluorescence system of lead with GA were studied. The lead ion can form a stable binary chelate with GA, having a ratio of 1:2 in the pH range 7.0‐8.0. The maximum excitation and emission wavelengths are 205.0 nm and 308.8 nm for the lead chelate, respectively. The reaction is instantaneous and the fluorescence intensity of the lead chelate remains stable from 20 to 150 min. Under the optimal experimental conditions the fluorescence intensity is a linear function of concentration in the range 1.0‐10.0 ng/mL of lead and the detection limit is 0.52 ng/mL of lead. Interferences of other ions were studied. The method has been successfully applied to the determination of lead in common paint.     

氢化物发生-原子吸收光谱法测定柠檬酸中微量铅

柠檬酸样品经硫酸处理及在550℃灼烧灰化,残渣溶于盐酸(5+95)溶液中。用铁氰化钾将溶液中铅(Ⅱ)氧化成铅(Ⅳ),然后再以硼氢化钾为还原剂,盐酸(1+99)溶液为载流,用氢化物发生-原子吸收光谱法测定铅含量。在优化的试验条件下,铅的质量浓度在20μg·L~(-1)以内与其吸光度呈线性关系,检出限(3σ)为2.6μg·L~(-1)。用此方法分析了3个柠檬酸样品,测定值的相对标准偏差(n=6)小于5%,加标回收率在90.5%～110.0%之间。     

A Durable Catalyst for Vapor Phase Nitration of Benzene with Nitric Acid

Nitrobenzene is one of the most important chemical intermediates, for preparing drugs, pesticides and explosive etc. For more than a century, it has been commercially manufactured by reacting benzene with mixed acid in liquid phase under vigorous agitation. Despite the high efficiency, the mixed-acid process has some drawbacks, among which the huge amount of spent acid and wastewater are by far the most crucial, and this makes an alternative solution desirable. Nitration of benzene over sol…