色谱柱为什么能把混合物中的各个组分排队分开？
Why does a chromatography column sort the components of a mixture into separate bands?
色谱利用各组分在固定相与流动相之间分配行为的差异。样品随流动相（液体或气体）流过固定相（固体吸附剂或涂在载体上的液膜），不同分子在被固定相拉住和随流动相前进之间竞争：亲和力弱的组分大部分时间随流动相走，跑得快，先流出；亲和力强的被滞留更久，后流出。各组分因迁移速度不同而逐步拉开距离，先后到达检测器，峰面积还能定量给出各组分的含量。
Chromatography exploits differences in how components distribute between a stationary phase and a mobile phase. The sample rides the mobile phase (liquid or gas) over the stationary phase (a solid adsorbent or a liquid film on a support), and each molecule competes between being held by the stationary phase and moving with the mobile phase. Components that interact weakly spend most of their time travelling and elute first; strongly held ones linger and elute later. As their migration speeds differ they spread into separate peaks at the detector, and peak areas can quantify each component.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#色谱 #固定相 #流动相
电位分析法（如 pH 计）依据什么？
On what does potentiometric analysis (e.g., a pH meter) rely?
电位分析法通过测量指示电极与参比电极组成的电池电动势来测定离子活度。pH 玻璃电极对 H⁺ 敏感，其电位随 pH 线性变化，再与稳定参比电极比较得到读数。它快速、非破坏性，广泛用于现场检测。
Potentiometry measures the electromotive force of a cell made of an indicator and a reference electrode to determine ion activity. A pH glass electrode is sensitive to H⁺, its potential varying linearly with pH, compared against a stable reference. It is fast and non-destructive, widely used in field testing.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
武汉大学《分析化学》
Analytical Chemistry (Wuhan Univ.)
#电位分析 #pH计 #参比电极
什么是返滴定？什么时候需要用到它？
What is back titration, and when is it needed?
返滴定是先加入过量已知浓度的试剂与被测物反应，再用另一种标准溶液滴定剩余的试剂。当被测物难溶、反应慢或没有合适指示剂时使用，例如测定碳酸钙：先加过量盐酸将其溶解，再用标准氢氧化钠返滴剩余盐酸，实际消耗量等于加入量减去剩余量。
In back titration, an excess of a reagent of known concentration is added to react with the analyte, and the remaining reagent is then titrated with a second standard solution. It is used when the analyte is sparingly soluble, reacts slowly, or lacks a suitable indicator - for instance, calcium carbonate is dissolved in excess HCl and the leftover acid is back-titrated with standard NaOH; the amount consumed is the added amount minus the remainder.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#返滴定 #滴定分析 #碳酸钙
质谱仪怎样识别分子？
How does a mass spectrometer identify molecules?
样品先被电离成带电碎片，再按质荷比（m/z）在电场或磁场中分离，得到的谱图峰位与相对强度可推断分子量与结构。McLafferty 与 Tureček 的《质谱解析》是碎片规律的标准参考。
The sample is ionized into charged fragments, then separated by mass-to-charge ratio (m/z) in electric or magnetic fields; the peak positions and intensities reveal molecular weight and structure. McLafferty and Tureček's 'Interpretation of Mass Spectra' is the standard reference on fragmentation.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Harris《定量分析化学》；McLafferty 与 Tureček《质谱解析》
Harris, Quantitative Chemical Analysis; McLafferty & Tureček, Interpretation of Mass Spectra
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL2747424W：Quantitative chemical a
#质谱 #质荷比 #电离
系统误差和随机误差有什么区别？怎样分别减少它们？
What is the difference between systematic and random error, and how is each reduced?
系统误差方向和大小时刻一定，来自仪器未校准、方法缺陷或试剂不纯，重复测量无法减小，须通过校准仪器、空白试验、对照试验或使用标准物质来校正。随机误差围绕真值随机波动，来自读数估读、温度微小变化等，增加测量次数取平均可减小。准确度主要受系统误差影响，精密度反映随机误差的大小。
Systematic error has a fixed direction and magnitude, caused by uncalibrated instruments, flawed methods or impure reagents; repeating measurements does not reduce it, and it is corrected by calibrating instruments, running blanks and controls, or using reference standards. Random error fluctuates around the true value, arising from reading estimation, slight temperature drift, and similar factors; averaging more measurements reduces it. Accuracy is limited mainly by systematic error, while precision reflects random error.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#系统误差 #随机误差 #准确度
EDTA络合滴定为什么能用于测定多种金属离子？滴定中常加入缓冲溶液和指示剂的原因是什么？
Why can EDTA complexometric titration determine many different metal ions, and why are buffer solutions and indicators added?
EDTA（乙二胺四乙酸）能与几乎全部金属离子形成稳定且通常为1:1的螯合物，因此可用于广泛金属离子的定量测定。滴定需在受控pH（常加氨—铵盐缓冲液）下进行，因为EDTA的配位能力与pH密切相关；金属指示剂则在终点时因EDTA夺取金属离子而变色指示。
EDTA (ethylenediaminetetraacetic acid) forms stable, usually 1:1 chelates with nearly all metal ions, so it can quantify a wide range of them. The titration is run at a controlled pH (often an ammonia-ammonium buffer) because EDTA's complexing ability depends strongly on pH, and a metal indicator signals the endpoint by changing color when EDTA displaces it from the metal ion.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
华中师范大学、东北师范大学、陕西师范大学《分析化学》（第四版），高等教育出版社
Central China Normal University et al., 'Analytical Chemistry' (4th ed.), Higher Education Press
#EDTA #络合滴定 #螯合 #缓冲溶液 #金属指示剂
质谱仪凭什么能称出分子的质量？
How can a mass spectrometer weigh a molecule?
质谱先把样品分子电离成带正电的离子，再让它们在电场中加速、进入磁场或飞行管，离子运动的弯曲程度或飞行时间取决于质荷比 m/z。同样电荷下，质量越小的离子偏转越厉害，检测器按 m/z 从小到大记录出峰，形成质谱图。分子离子峰给出分子的相对分子质量，碎片离子峰则反映分子断裂的方式，帮助推断结构；高分辨质谱甚至可以区分相差不足一个电子质量的分子。
A mass spectrometer ionizes sample molecules into positively charged ions, accelerates them in an electric field, and sends them through a magnetic sector or a flight tube, where how much they curve or how long they fly depends on the mass-to-charge ratio m/z. For equal charge, lighter ions deflect more, and the detector records peaks from small to large m/z, producing a mass spectrum. The molecular-ion peak gives the relative molecular mass, while fragment-ion peaks reveal how the molecule breaks apart and help infer its structure; high-resolution instruments can even tell apart molecules differing by far less than one electron's mass.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#质谱 #质荷比 #分子量
什么是同位素稀释质谱法？为什么它被认为是"仲裁级"的准确定量方法？
What is isotope-dilution mass spectrometry, and why is it regarded as a "definitive" quantitative method?
方法先向样品加入已知量的同位素标记（如 ¹³C 标记）内标，让它和待测物均匀混合；由于两者化学性质相同、分离行为一致，任何前处理损失对二者比例都无影响。用质谱测同位素比值即可反推原含量，几乎不受回收率偏差干扰，故常用于标准物质定值。
The method spikes the sample with a known amount of an isotope-labeled (e.g., ¹³C) internal standard that mixes homogeneously with the analyte; because the two share identical chemistry and separation behavior, any processing loss affects their ratio equally. Measuring the isotope ratio by mass spectrometry back-calculates the original amount, largely immune to recovery errors, so it is used to certify reference materials.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
NIST 标准参考物质方法（同位素稀释质谱）；Skoog 等《分析化学基础》第9版
NIST Standard Reference Materials — isotope-dilution MS; Skoog et al., "Fundamentals of Analytical Chemistry" (9th ed.)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL2762928W：Fundamentals of analyti
#同位素稀释 #质谱 #内标 #标准物质定值
红外光谱为什么能看出分子里有哪些官能团？
How can infrared spectroscopy tell which functional groups a molecule contains?
分子中的化学键像弹簧一样以特征频率振动（伸缩、弯曲等）。当红外光频率与某化学键的振动频率相等时，该键吸收红外能量、振动加剧，在光谱上出现吸收峰。不同官能团因原子质量和键强不同，吸收峰位置固定：例如羟基 O-H 在3300到2500 cm-1 附近出宽峰，羰基 C=O 在1700 cm-1 左右出强峰。把未知物的红外谱图与特征吸收表对照，就能确认它含哪些官能团，是鉴定未知有机化合物的常规手段。
Chemical bonds behave like springs vibrating at characteristic frequencies (stretching, bending). When the frequency of infrared light matches a bond's vibration frequency, the bond absorbs that energy and vibrates more strongly, producing an absorption peak. Each functional group absorbs at a characteristic position set by its atom masses and bond strength - for instance, O-H gives a broad band around 3300-2500 cm⁻¹ and C=O a strong peak near 1700 cm⁻¹. Matching the spectrum of an unknown compound against tables of characteristic absorptions therefore reveals its functional groups, making IR a routine tool for identifying organic compounds.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#红外光谱 #官能团 #振动
尿样中痕量的兴奋剂是怎么被查出来的？为什么需要两种仪器联用？
How are trace amounts of doping agents found in a urine sample, and why do labs combine two instruments?
实验室先把尿样经固相萃取等前处理富集，再送入气相色谱-质谱联用仪（GC-MS）。气相色谱先把混合物按极性、沸点等差异在毛细管柱中分离成单一组分，随后质谱把每个组分离子化、给出特征质谱图，像指纹一样与标准品比对。色谱负责分离定量，质谱负责定性确认，两者串联既灵敏又能排除假阳性，所以成为兴奋剂检测的国际标准配置。
Labs first concentrate the urine with cleanup steps such as solid-phase extraction, then run it through gas chromatography-mass spectrometry (GC-MS). The GC column separates the mixture into individual components by differences in polarity and boiling point; the mass spectrometer then ionizes each one and records a characteristic spectrum that acts like a fingerprint to match against reference standards. Chromatography provides separation and quantification while mass spectrometry confirms identity, so combining them gives both sensitivity and freedom from false positives - the international standard setup for doping control.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#兴奋剂检测 #气质联用 #痕量分析
重量分析法的基本思路是什么？
What is the basic idea of gravimetric analysis?
将待测组分通过沉淀、挥发或电解转化为已知组成的纯物质，精确称量其质量，再按化学计量换算为原组分含量。关键是沉淀要完全、纯净且易过滤，常用于高准确度测定。
Convert the analyte into a pure substance of known composition by precipitation, volatilization, or electrolysis, weigh it precisely, then use stoichiometry to back-calculate the original amount. Complete, pure, filterable precipitates are essential, giving highly accurate results.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#重量分析 #沉淀 #称量
比尔—朗伯定律（Beer-Lambert law）的内容是什么？它在分析化学中有什么用途？
What does the Beer-Lambert law state, and what is its use in analytical chemistry?
比尔—朗伯定律指出，溶液对单色光的吸光度A与吸光物质的浓度c和光程长度l成正比，即 A = ε·c·l（ε为摩尔吸光系数）。利用该关系可通过测量吸光度来定量测定溶液中物质的浓度，是紫外—可见分光光度法的理论基础。
The Beer-Lambert law states that the absorbance A of a solution at a given wavelength is directly proportional to the concentration c of the absorbing species and the path length l: A = ε·c·l, where ε is the molar absorptivity. It allows quantitative determination of concentration from measured absorbance and underlies UV-visible spectrophotometry.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
华中师范大学、东北师范大学、陕西师范大学《分析化学》（第四版），高等教育出版社
Central China Normal University et al., 'Analytical Chemistry' (4th ed.), Higher Education Press
#比尔—朗伯定律 #吸光度 #分光光度法 #浓度 #摩尔吸光系数
分液漏斗是用来干什么的？什么情况下使用它？
What is a separating funnel for, and when is it used?
分液漏斗用于分离两种互不相溶、密度不同的液体，比如水和油的混合物。把液体倒入漏斗静置分层后，打开下方活塞先放出下层液体，再把上层液体从漏斗口倒出。萃取实验常与分液漏斗配合：将水相和有机相振荡混合、静置后再分液。
A separating funnel separates two immiscible liquids of different densities, such as water and oil. After the mixture settles into layers, the lower layer is drained through the stopcock and the upper layer is poured out of the top. It is usually paired with extraction: aqueous and organic phases are shaken together, allowed to settle, then separated.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
邢其毅 等,《基础有机化学》第4版,北京大学出版社,2016
Xing Qiyi et al., Basic Organic Chemistry, 4th ed., Peking University Press, 2016
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787301272121（豆瓣书目条目: 基础有机化学）
#分液漏斗 #萃取 #液液分离
什么是基准物质？它在分析中有何作用？
What is a primary standard and what role does it play?
基准物质是纯度高、组成确定、稳定且摩尔质量较大的物质，可直接配制标准溶液。例如邻苯二甲酸氢钾、碳酸钠常用于标定酸或碱的浓度。它保证了滴定等定量分析的准确起点。
A primary standard is a highly pure, well-defined, stable substance with a large molar mass that can directly make a standard solution. Potassium hydrogen phthalate and sodium carbonate, for example, standardize acid or base concentrations. It ensures an accurate starting point for titrations.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
武汉大学《分析化学》
Analytical Chemistry (Wuhan Univ.)
#基准物质 #标准溶液 #标定
怎么用滴定方法准确测出食醋中醋酸的含量？
How can titration accurately determine how much acetic acid is in vinegar?
用已知浓度的氢氧化钠标准溶液滴定一定量食醋，发生中和反应：CH3COOH+NaOH 生成 CH3COONa+H2O。当加入的氢氧化钠恰好与醋酸完全中和时到达化学计量点，用酚酞指示剂判断，终点时溶液由无色变浅红。根据 C酸乘V酸等于C碱乘V碱，就能算出醋酸的物质的量和浓度。食醋颜色深会干扰观察，通常先稀释再滴定。
A standard sodium hydroxide solution of known concentration is titrated into a measured portion of vinegar, neutralizing it: CH3COOH + NaOH → CH3COONa + H2O. When the added NaOH exactly consumes the acetic acid, the equivalence point is reached, detected with phenolphthalein as the solution turns from colourless to pale pink. The relation Cacid × Vacid = Cbase × Vbase then gives the amount and concentration of acetic acid. Dark vinegar is usually diluted first so the colour change is easy to see.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录仅给书名，无版次与年份；同一书名常对应多个版次，不臆测具体版本。
《普通化学》（酸碱滴定）
General Chemistry (acid-base titration)
#滴定 #食醋 #中和
分析化学中系统误差与随机误差有何区别？
How do systematic and random errors differ in analytical chemistry?
系统误差由固定原因（仪器未校准、方法缺陷）引起，方向恒定、可修正，决定结果的准确度。随机误差来自不可控波动，大小方向随机，决定精密度，可通过多次测量取平均减小。两者共同影响分析质量。
Systematic error arises from fixed causes (uncalibrated instrument, flawed method), is constant in direction, and is correctable—it sets accuracy. Random error comes from uncontrollable fluctuations, varies unpredictably, and sets precision; averaging replicate measurements reduces it. Both shape analytical quality.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
武汉大学《分析化学》
Analytical Chemistry (Wuhan Univ.)
#系统误差 #随机误差 #准确度
为什么检测水中十亿分之一量级的污染物，不能只靠看颜色或简单的化学方法？
Why can't visual checks or simple chemistry alone detect pollutants present at one part per billion in water?
简单化学方法通常只能检测到毫克/升量级的成分，而痕量污染物浓度低至微克甚至纳克/升，远超常规方法的灵敏度极限，颜色反应根本看不到信号。仪器分析如色谱-质谱联用能先把目标物分离，再以极高灵敏度逐一计数分子，把信号从噪声中提取出来。而且这类污染物成分复杂，需要同时确认是什么和有多少，只有联用技术才能给出定性与定量结果。
Simple chemical tests typically reach only milligram-per-litre concentrations, while trace pollutants sit at microgram or even nanogram per litre - far beyond the sensitivity limit of routine methods, so colour reactions show no signal at all. Instrumental analysis such as chromatography-mass spectrometry first separates the target compound, then counts its molecules with extreme sensitivity, pulling the signal out of the noise. And because such mixtures are complex, labs need to know both what is present and how much, which only combined techniques deliver.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#痕量检测 #灵敏度 #仪器分析
酸碱滴定中指示剂（如酚酞）为什么会在特定pH附近变色？如何选择指示剂？
Why do acid-base titration indicators such as phenolphthalein change color near a specific pH, and how should an indicator be chosen?
指示剂本身是弱酸或弱碱，其酸式与碱式具有不同颜色，颜色随溶液pH在某一范围内（变色范围）突变。选择指示剂时应使其变色范围落在滴定突跃区间内，例如强酸强碱滴定可用酚酞或甲基橙，而弱酸滴定宜选用酚酞等变色在碱区的指示剂。
An indicator is itself a weak acid or base whose acid and base forms have different colors, and the color switches over a certain pH interval (its transition range). The indicator should be chosen so its transition range falls within the titration's sharp pH jump—e.g., phenolphthalein or methyl orange for strong acid-strong base titrations, and phenolphthalein for titrating weak acids.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
华中师范大学、东北师范大学、陕西师范大学《分析化学》（第四版），高等教育出版社
Central China Normal University et al., 'Analytical Chemistry' (4th ed.), Higher Education Press
#滴定 #指示剂 #酚酞 #pH #突跃
简单蒸馏和分馏有什么区别？各自适合什么情况？
What is the difference between simple and fractional distillation, and when is each used?
简单蒸馏是把液体加热气化再冷凝，适合分离沸点相差较大的液体或除去溶剂；分馏在蒸馏瓶上方加装分馏柱，蒸气与回流液在柱内反复冷凝和汽化，相当于连续多次蒸馏，能分离沸点接近的液体。石油加工、乙醇提纯使用的就是分馏技术。
Simple distillation vaporizes a liquid and condenses it again, suitable for separating liquids with very different boiling points or for removing a solvent. Fractional distillation adds a fractionating column where vapor and refluxing liquid repeatedly condense and re-vaporize, effectively many distillations in one, and can separate close-boiling liquids. Petroleum refining and ethanol purification use fractionation.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#蒸馏 #分馏 #分馏柱
什么是有效数字？计算时应该怎样保留？
What are significant figures, and how should they be handled in calculations?
有效数字是测量结果中能真实反映精度的数字位数，例如刻度到0.1毫升的量筒读出15.6毫升，就是三位有效数字。乘除法结果与参与运算中有效数字最少者相同，加减法则按小数点后位数最少者确定。多写出的位数并不代表真实精度。
Significant figures are the digits in a measurement that genuinely reflect its precision; for example, a reading of 15.6 mL on a 0.1-mL-graduated cylinder has three significant figures. In multiplication and division the result keeps as many significant figures as the least precise factor, while in addition and subtraction it follows the operand with the fewest decimal places. Extra digits do not represent real precision.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#有效数字 #误差 #测量
质谱法（mass spectrometry）是怎样测定分子质量的？质荷比m/z代表什么？
How does mass spectrometry determine molecular mass, and what does the mass-to-charge ratio m/z represent?
质谱先将样品分子电离成带电离子，再在电场和磁场中按质荷比（m/z，质量与电荷数之比）分离并检测。分子离子峰的m/z对应分子的相对分子质量，而碎片离子峰则提供分子结构信息，是现代有机物结构鉴定的核心手段。
Mass spectrometry first ionizes sample molecules into charged ions, then separates and detects them according to their mass-to-charge ratio m/z (mass divided by charge number) in electric and magnetic fields. The molecular ion peak's m/z gives the relative molecular mass, while fragment ion peaks reveal structural information, making MS central to organic structure identification.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
华中师范大学、东北师范大学、陕西师范大学《分析化学》（第四版），高等教育出版社
Central China Normal University et al., 'Analytical Chemistry' (4th ed.), Higher Education Press
#质谱 #质荷比 #分子离子 #电离 #碎片
原子吸收光谱（AAS）是怎样测出样品中某种金属的含量（比如血里的铅）的？
How does atomic absorption spectroscopy (AAS) measure the amount of a metal such as lead in a sample?
样品被雾化并高温原子化后，基态原子只吸收该元素特征波长的光（如铅 283.3 nm）。吸光度与光路中该原子的数目成正比，按朗伯-比尔定律 A = εlc 换算，再对照标准曲线即可得出浓度。
The sample is nebulized and atomized at high temperature; ground-state atoms absorb only their element-specific wavelength (e.g., lead at 283.3 nm). Absorbance is proportional to the number of those atoms in the light path, and by the Beer–Lambert law A = εlc, compared against a calibration curve, the concentration is obtained.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Skoog, West, Holler & Crouch《分析化学基础》（第9版），第9章
Skoog, West, Holler & Crouch, "Fundamentals of Analytical Chemistry" (9th ed.), Ch.9
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL2762928W：Fundamentals of analyti
#原子吸收光谱 #元素分析 #朗伯比尔定律 #血铅
分光光度法怎样用标准曲线测定未知浓度？
How does spectrophotometry use a standard curve to find an unknown concentration?
根据比尔-朗伯定律A等于吸光系数乘光程乘浓度，同一物质在固定波长下吸光度与浓度成正比。先配制一系列已知浓度的标准溶液，在最大吸收波长处测吸光度，绘制吸光度-浓度标准曲线；再测未知样品吸光度，从曲线上读出浓度，前提是样品浓度落在曲线的线性范围内。
By the Beer-Lambert law, A equals molar absorptivity times path length times concentration, so at a fixed wavelength absorbance is proportional to concentration for a given substance. Prepare a series of standard solutions of known concentration, measure their absorbance at the absorption maximum, plot the standard curve, then read the unknown concentration from its absorbance - provided it falls within the linear range of the curve.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#标准曲线 #分光光度法 #比尔-朗伯定律
什么是重量分析法？
What is gravimetric analysis?
重量分析是通过化学反应把待测组分转化为组成确定的沉淀，经过滤、洗涤、干燥或灼烧后称量其质量来定量。例如用 BaCl₂ 把硫酸根沉淀为 BaSO₄ 再称重。它以准确著称，但操作较繁琐。
Gravimetric analysis converts the analyte into a well-defined precipitate by a chemical reaction, then filters, washes, dries or ignites, and weighs it to quantify. For example, sulfate is precipitated as BaSO₄ with BaCl₂ and weighed. It is highly accurate but laborious.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
武汉大学《分析化学》
Analytical Chemistry (Wuhan Univ.)
#重量分析 #沉淀 #硫酸钡
为什么化验之前常常要先"校准"仪器（比如用标准溶液去对一下）？
Why do we calibrate an instrument (e.g., with a standard solution) before taking measurements?
仪器读数和真实值之间常有固定的偏差（如 pH 电极老化、天平零点漂移）。校准就是用已知准确浓度的标准物质去"对表"，把系统误差修正掉，这样后续测未知样品时才可靠、可比较。
Instrument readings usually carry a fixed offset from the true value (e.g., an aged pH electrode, a drifting balance zero). Calibration "sets the clock" using a substance of known accurate concentration, correcting systematic error so later unknown measurements are reliable and comparable.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Skoog, West, Holler & Crouch《分析化学基础》（第9版），第1章
Skoog, West, Holler & Crouch, "Fundamentals of Analytical Chemistry" (9th ed.), Ch.1
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL2762928W：Fundamentals of analyti
#校准 #标准溶液 #系统误差 #分析化学
读量筒刻度时为什么要平视液面凹面最低处？
Why read a graduated cylinder at the meniscus bottom, eye level?
液体在细管里会形成凹液面，俯视或仰视都会读偏，平视凹面最低点才准确。
Liquid forms a concave meniscus in narrow tubes; reading at eye level at the lowest point avoids parallax error.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#量筒 #凹液面 #读数
什么是滴定分析？
What is titration analysis?
滴定是将已知浓度的标准溶液逐滴加到待测溶液中，直到反应定量完成（等当点）的分析方法。借助指示剂或仪器判断终点，再由体积和浓度算出待测物含量。它操作简便、准确，是经典的定量化学分析手段。
Titration adds a standard solution of known concentration dropwise to the sample until the reaction is complete (equivalence point). A visual indicator or instrument signals the end point, and the unknown amount is calculated from volumes and concentrations. It is a simple, accurate classical quantitative method.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
武汉大学《分析化学》
Analytical Chemistry (Wuhan Univ.)
#滴定 #等当点 #标准溶液
色谱法（chromatography）分离混合物的基本原理是什么？
What is the basic principle by which chromatography separates mixtures?
色谱法利用混合物中各组分在固定相和流动相之间分配（或吸附）能力的差异来实现分离。与固定相作用弱、随流动相移动快的组分先流出，作用强的后流出，从而将复杂混合物逐一分开，常见有气相色谱和液相色谱等。
Chromatography separates a mixture based on differences in how each component partitions (or adsorbs) between a stationary phase and a mobile phase. Components that interact weakly with the stationary phase move faster with the mobile phase and elute first, while strongly interacting ones elute later, separating complex mixtures; common forms include gas and liquid chromatography.
难度 入门 · 适合 初中(12-15)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
华中师范大学、东北师范大学、陕西师范大学《分析化学》（第四版），高等教育出版社
Central China Normal University et al., 'Analytical Chemistry' (4th ed.), Higher Education Press
#色谱 #固定相 #流动相 #分离 #分配
酸碱指示剂为什么会在不同 pH 变色？
Why do acid–base indicators change color at different pH?
指示剂多是弱有机酸或弱碱，其酸式与碱式具有不同颜色结构。随着 pH 改变，二者比例按酸碱平衡移动，当某形式占优时便呈现其颜色。酚酞在酸性无色、碱性变红就是典型例子。
Indicators are usually weak organic acids or bases whose acid and base forms have different colored structures. As pH changes, their ratio shifts with acid–base equilibrium, and the dominant form shows its color. Phenolphthalein is colorless in acid and red in base—a classic case.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
武汉大学《分析化学》
Analytical Chemistry (Wuhan Univ.)
#酸碱指示剂 #变色 #酚酞
焰色反应是什么？为什么金属盐会呈现不同颜色？
What is the flame test and why do metal salts show different colors?
焰色反应是某些金属离子在无色火焰中受热时，电子被激发到高能级，回落时发射特定波长光的现象。钠呈黄色、钾呈紫色、铜呈绿色，源于不同元素的特征能级差。它曾用于快速鉴别金属元素。
The flame test occurs when certain metal ions are heated in a colorless flame, exciting electrons that emit light of specific wavelengths as they fall back. Sodium appears yellow, potassium violet, copper green, due to each element's characteristic level spacings. It was used for rapid elemental identification.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
武汉大学《分析化学》
Analytical Chemistry (Wuhan Univ.)
#焰色反应 #电子跃迁 #特征波长
滴定中的终点与等当点有何区别？
What is the difference between endpoint and equivalence point in a titration?
等当点是化学计量上恰好完全反应的理论点；终点是实验者通过指示剂变色或仪器信号观察到的实际点。理想情况下二者重合，但指示剂选择不当会造成滴定误差。
The equivalence point is the theoretical stoichiometric completion of reaction; the endpoint is the actual observed change (indicator color, instrument signal). Ideally they coincide, but poor indicator choice causes titration error.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#滴定 #等当点 #终点
定性分析与定量分析分别回答什么问题？
What questions do qualitative and quantitative analyses answer?
定性分析回答“有什么”（鉴别物质或离子是否存在），如焰色反应、沉淀试验；定量分析回答“有多少”（测定含量或浓度），如滴定、光谱定量。二者常先定性后定量。
Qualitative analysis answers 'what is present' (identify substances or ions), e.g., flame tests or precipitation; quantitative analysis answers 'how much' (content or concentration), e.g., titration or spectrophotometry. Often you identify first, then quantify.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
D. C. Harris, Quantitative Chemical Analysis, 9th ed., W. H. Freeman, 2015
D. C. Harris, Quantitative Chemical Analysis, 9th ed., W. H. Freeman, 2015
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL2747424W：Quantitative chemical a
#定性 #定量 #分析
硼砂珠试验怎么给金属“上色”？
How does the borax-bead test color metals?
熔融硼砂与金属氧化物生成有色的偏硼酸盐玻璃珠，依金属不同而显不同颜色，用于辅助鉴别。
Molten borax forms colored metaborate glass beads with metal oxides, whose color varies by metal and aids identification.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#硼砂珠 #显色 #鉴别