阿伦尼乌斯公式是什么？
What is the Arrhenius equation?
阿伦尼乌斯公式表达为k = A·e^(-Ea/RT)，其中k是速率常数，A是指前因子，Ea是活化能，R是气体常数，T是绝对温度。它说明速率常数随温度升高呈指数增长。对该式取对数可线性化处理并求得活化能。
The Arrhenius equation is k = A·e^(-Ea/RT), where k is the rate constant, A the pre-exponential factor, Ea the activation energy, R the gas constant and T the absolute temperature. It shows the rate constant grows exponentially with temperature. Taking logarithms linearizes it and allows determination of activation energy.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-04
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Arrhenius,《Über die Reaktionsgeschwindigkeit bei der Inversion von Rohrzucker durch Säuren》,Zeitschrift für Physikalische Chemie,1889 (DOI: 10.1515/zpch-1889-0116)
Arrhenius, 'Über die Reaktionsgeschwindigkeit bei der Inversion von Rohrzucker durch Säuren', Zeitschrift für Physikalische Chemie, 1889, DOI: 10.1515/zpch-1889-0116
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1515/zpch-1889-0116
#阿伦尼乌斯 #速率常数 #活化能
为什么碳酸钙在常温下很稳定，在水泥窑高温下却会分解成氧化钙和二氧化碳？
Why is calcium carbonate stable at room temperature yet decomposes into quicklime and carbon dioxide at kiln temperatures?
碳酸钙分解是吸热且熵增的反应：ΔH>0 不利，ΔS>0 有利，判断取决于 ΔG=ΔH-TΔS 的符号。常温下 TΔS 项很小，ΔG>0，反应不自发；高温时 TΔS 项增大到超过 ΔH，ΔG<0，分解才得以进行。因为 ΔH 和 ΔS 本身随温度变化不大，这类分解反应普遍具有明显的起始温度，石灰窑必须维持约900摄氏度才能连续产出生石灰。
The decomposition is endothermic and entropy-increasing: ΔH > 0 opposes it, ΔS > 0 favours it, and the balance is set by the sign of ΔG = ΔH - TΔS. At room temperature the TΔS term is small, so ΔG > 0 and nothing happens; at kiln temperatures TΔS grows until it exceeds ΔH, ΔG turns negative and decomposition proceeds. Since ΔH and ΔS barely change with temperature, such decompositions show a well-defined onset temperature, and lime kilns must be kept near 900 °C to make quicklime continuously.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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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
#吉布斯自由能 #分解 #温度
什么是缓冲溶液？
What is a buffer solution?
缓冲溶液由弱酸及其共轭碱（或弱碱及其共轭酸）组成，能抵抗少量外加酸、碱或稀释而保持pH基本不变。其原理是共轭对通过消耗加入的H+或OH-来维持平衡。人体血液就依靠碳酸-碳酸氢盐缓冲体系维持酸碱稳定。
A buffer solution contains a weak acid and its conjugate base (or a weak base and its conjugate acid) and resists changes in pH upon adding small amounts of acid, base or dilution. The conjugate pair consumes added H+ or OH- to maintain equilibrium. Human blood relies on the carbonic acid-bicarbonate buffer to stay stable.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
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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。
Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）酸碱缓冲溶液章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (buffer solutions)
#缓冲溶液 #pH #共轭酸碱
什么是熵？
What is entropy?
熵是体系混乱度或无序程度的度量，符号为S。在自发过程中孤立体系的熵总趋于增大（热力学第二定律）。气体比液体、液体比固体熵更大，因为微粒运动自由度更高。熵变与焓变共同决定过程是否自发。
Entropy, symbol S, measures the disorder or randomness of a system. In spontaneous processes the entropy of an isolated system tends to increase (the second law of thermodynamics). Gases have higher entropy than liquids and liquids than solids because of greater freedom of motion. Entropy change and enthalpy change together decide spontaneity.
难度 专业 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
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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。
Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）熵与热力学第二定律章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (entropy; second law of thermodynamics)
#熵 #混乱度 #热力学
过渡态理论（Eyring 方程）如何把反应速率和活化自由能联系起来？
How does transition-state (Eyring) theory link reaction rate to activation free energy?
Eyring 方程 k = (k_B T / h)·e^(−ΔG‡/RT) 把速率常数与反应物到过渡态的活化吉布斯自由能 ΔG‡ 直接挂钩。温度升高使指数项增大、速率加快；在室温附近，ΔG‡ 每升高约 5.7 kJ/mol，速率大约降低一个数量级。
The Eyring equation, k = (k_B T / h)·exp(−ΔG‡/RT), relates the rate constant directly to the activation Gibbs free energy ΔG‡ between reactants and the transition state. Raising temperature increases the exponential term, and at room temperature each ~5.7 kJ/mol rise in ΔG‡ slows the reaction by roughly a factor of ten.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-03
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Atkins & de Paula《物理化学》（第10版），第22章
Atkins & de Paula, "Physical Chemistry" (10th ed.), Ch.22
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL1907523W：Physical chemistry（首版 1
#Eyring方程 #过渡态理论 #活化自由能 #速率常数
温度对化学平衡的影响方向如何判断？
How do you determine the direction of temperature's effect on equilibrium?
升温总是使平衡向吸热方向移动，降温则向放热方向移动，与勒夏特列原理一致。判断需先确定正反应是吸热还是放热（由焓变ΔH符号决定）。对于放热反应，升温会使平衡常数K减小、平衡左移。
Heating always shifts equilibrium toward the endothermic direction and cooling toward the exothermic direction, consistent with Le Chatelier's principle. First determine whether the forward reaction is endothermic or exothermic (from the sign of ΔH). For an exothermic reaction, heating lowers K and shifts equilibrium left.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
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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。
Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）温度对平衡的影响（范特霍夫方程）章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (temperature effect on equilibrium; van't Hoff equation)
#温度 #平衡 #焓变
合成氨反应是放热且气体分子数减少的反应，为什么工业上偏偏采用高压而不是过高的温度？
The Haber process is exothermic and reduces the number of gas molecules. Why does industry use high pressure but not extremely high temperature?
勒夏特列原理指出：改变条件时，平衡会向抵消这种改变的方向移动。N2+3H2 可逆生成 2NH3 是放热反应，升温会推动平衡逆向移动、降低产率，所以工业上只用约450摄氏度作为催化剂活性的折中，并不追求更高温度。而高压使气体总体积减小，平衡向生成2分子氨的方向移动，直接提高转化率，因此采用200到300个大气压。实际温度的选择是反应速率与平衡产率之间的平衡：太低反应太慢，太高催化剂易失效。
Le Chatelier's principle says a system at equilibrium shifts to counteract a change in conditions. The reaction N2 + 3H2 ⇌ 2NH3 is exothermic, so higher temperature pushes the equilibrium backward and cuts the yield; industry therefore uses about 450 °C as a compromise for catalyst activity but avoids going hotter. High pressure shrinks the total gas volume, so the equilibrium shifts toward two molecules of ammonia and raises conversion - hence pressures of 200-300 atmospheres. The temperature is really a trade-off between reaction speed and equilibrium yield: too low and the reaction crawls, too high and both yield and catalyst suffer.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
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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》（化学平衡）
General Chemistry (chemical equilibrium)
#勒夏特列原理 #合成氨 #化学平衡
什么是吉布斯自由能？
What is Gibbs free energy?
吉布斯自由能G = H - TS，综合了体系的焓、温度和熵。在恒温恒压下，ΔG < 0 的反应自发进行，ΔG = 0 时达平衡，ΔG > 0 则非自发。它是判断化学反应方向与限度的核心判据。
Gibbs free energy G = H - TS combines a system's enthalpy, temperature and entropy. At constant temperature and pressure, a reaction with ΔG < 0 is spontaneous, ΔG = 0 means equilibrium and ΔG > 0 means non-spontaneous. It is the central criterion for reaction direction and extent.
难度 专业 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
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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。
Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）吉布斯自由能章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (Gibbs free energy)
#吉布斯自由能 #自发 #判据
为什么有的过程明明是吸热的，却依然能自发进行？
Why can some processes proceed spontaneously even though they absorb heat?
自发性不能只看焓变（吸热还是放热），还要看熵变。冰在0摄氏度以上融化、硝酸铵在水中溶解都是吸热的，却会自发发生，因为固体变成液体或溶解后分子排列更混乱，体系熵增大，提供了驱动力。真正的判据是吉布斯自由能 ΔG=ΔH-TΔS：放热（ΔH<0）或熵增（ΔS>0）都有利于ΔG<0。吸热而能自发，靠的正是熵增那一项在常温或高温下压过了吸热的代价。
Spontaneity is not decided by enthalpy alone - whether heat is released or absorbed - but also by entropy. Ice melting above 0 °C and ammonium nitrate dissolving in water are endothermic yet spontaneous, because a solid turning into a liquid or a salt dissolving makes the molecular arrangement more disordered, increasing entropy and supplying the driving force. The true criterion is the Gibbs free energy ΔG = ΔH - TΔS: both releasing heat (ΔH < 0) and gaining entropy (ΔS > 0) favour ΔG < 0. An endothermic process stays spontaneous when the +TΔS term outweighs the heat it must absorb.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
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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》（化学热力学）
General Chemistry (chemical thermodynamics)
#焓 #熵 #自发过程
什么是速率常数？
What is the rate constant?
速率常数k是速率方程中比例系数，反映反应在本征条件下的快慢，只与温度、催化剂和溶剂有关，与浓度无关。k越大反应越快。通过实验测定不同温度下的k可求取活化能。
The rate constant k is the proportionality coefficient in the rate law, reflecting how fast a reaction proceeds under intrinsic conditions; it depends only on temperature, catalyst and solvent, not on concentration. A larger k means a faster reaction. Measuring k at different temperatures lets one determine the activation energy.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
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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。
Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）化学动力学（速率常数）章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (rate constant)
#速率常数 #温度 #活化能
洛杉矶型光化学烟雾中,臭氧峰值为何出现在午后而不是早晨的交通高峰?
In Los Angeles-type photochemical smog, why does the ozone peak come in the afternoon rather than during the morning rush hour?
臭氧的净生成由阳光驱动,车流只是提供原料。清晨尾气排出大量NO与VOC,NO先把夜间残留的臭氧滴定消耗;随着太阳升高,NO2在波长小于420nm的光照下光解出氧原子,与O2结合生成O3,同时OH自由基氧化VOC产生的过氧自由基把NO转回NO2却不消耗臭氧,净生成速率午后最强,臭氧遂累积至峰值,傍晚光照减弱后回落。
Net ozone production is driven by sunlight; traffic only supplies the ingredients. The morning rush emits large amounts of NO and VOCs, and that NO first titrates away the ozone left over from the night. As the sun climbs, NO2 photolyzes under light shorter than 420 nm to release oxygen atoms that combine with O2 into O3, while peroxy radicals from the OH oxidation of VOCs recycle NO back to NO2 without touching ozone. Net production is strongest in the early afternoon, so ozone accumulates to a peak and then falls as the light fades toward evening.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
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J. H. Seinfeld、S. N. Pandis《Atmospheric Chemistry and Physics: From Air Pollution to Climate Change》,Wiley,2006
J. H. Seinfeld & S. N. Pandis, Atmospheric Chemistry and Physics: From Air Pollution to Climate Change, Wiley, 2006
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-119-22117-3 (2006, Wiley)
#光化学烟雾 #对流层臭氧 #自由基链反应
什么是溶度积？
What is the solubility product?
溶度积Ksp是难溶电解质饱和溶液中离子浓度幂之积的平衡常数，反映物质的溶解能力。当溶液中离子积大于Ksp时会产生沉淀，小于Ksp时沉淀会溶解。利用Ksp可进行沉淀分离和离子积判断。
The solubility product Ksp is the equilibrium constant equal to the product of ion concentrations (each to its power) in a saturated solution of a sparingly soluble electrolyte, reflecting its dissolution ability. When the ion product exceeds Ksp, a precipitate forms; below it, the precipitate dissolves. Ksp is used for precipitation separation and ion-product judgments.
难度 专业 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
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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。
Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）溶度积与沉淀平衡章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (solubility product)
#溶度积 #沉淀 #平衡常数
为什么很多化学反应看起来反应不完，反应物总剩下一部分？
Why do many chemical reactions never seem to finish, always leaving some reactant behind?
这类反应是可逆的，正反应和逆反应同时在发生，当两者速率相等时就达到了化学平衡，反应物和产物的量都不再变化。平衡点由平衡常数K决定，K等于产物浓度幂的乘积与反应物浓度幂的乘积之比；K越大，反应进行得越完全。改变温度等条件能移动平衡，但不能删掉逆反应，所以产物中总会残留一些反应物。
Such reactions are reversible: the forward and reverse reactions proceed simultaneously, and equilibrium is reached when their rates are equal, so reactant and product amounts stop changing. The equilibrium position is set by the equilibrium constant K, the ratio of product concentrations raised to their coefficients over the same for reactants; the larger K, the more complete the reaction. Changing conditions like temperature can shift the equilibrium, but it cannot delete the reverse reaction, so some reactant always remains.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 来源待核验 · Source pending review
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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》（化学平衡）
General Chemistry (chemical equilibrium)
#化学平衡 #平衡常数 #可逆反应
为什么升高温度能让大多数化学反应变快？
Why do higher temperatures speed up most chemical reactions?
反应要发生，分子必须带着足够的能量碰撞，撞断旧键、形成新键，这个能量门槛叫活化能。升温时分子的平均动能变大，更重要的是能量分布的高能尾部变厚，超过活化能的分子比例急剧增加，有效碰撞明显变多。温度每升高10摄氏度，许多反应速率约翻倍，正是这个原因。
For a reaction to happen, molecules must collide with enough energy to break old bonds and form new ones - the activation-energy barrier. Raising the temperature increases average kinetic energy, but the key is that the high-energy tail of the energy distribution swells, so the fraction of molecules above the barrier rises sharply and effective collisions multiply. That is why many reaction rates roughly double for every 10 °C rise.
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
#活化能 #碰撞理论 #反应速率
什么是电离平衡？
What is ionization equilibrium?
弱电解质在水中只部分电离，已电离的离子与未电离的分子之间存在动态平衡，称为电离平衡。以醋酸为例，其电离程度用电离常数Ka衡量。稀释溶液通常会使弱电解质的电离度增大。
A weak electrolyte ionizes only partially in water, and a dynamic equilibrium exists between the ions formed and the un-ionized molecules; this is ionization equilibrium. For acetic acid, the extent is described by the ionization constant Ka. Dilution usually increases the degree of ionization of a weak electrolyte.
难度 进阶 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
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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。
Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）酸碱电离平衡章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (ionization equilibria)
#电离平衡 #弱电解质 #电离常数
为什么许多化学反应在温度每升高10摄氏度后，速率会约增加一倍？
Why do many chemical reactions roughly double in rate for every 10 °C rise in temperature?
阿伦尼乌斯发现速率常数随温度按指数规律变化：k=A·e^(-Ea/RT)，其中Ea是活化能。温度升高使更多分子获得超过活化能的能量，有效碰撞比例成倍增加。对常见活化能（约50到100千焦/摩尔），在室温附近升高10摄氏度恰好使速率约翻倍。这是一条经验近似，活化能越高，翻倍效果越明显。
Arrhenius found that the rate constant grows exponentially with temperature, k = A·e^(-Ea/RT), where Ea is the activation energy. Warming the system raises the fraction of molecules that surpass the barrier, so effective collisions multiply; for typical activation energies (roughly 50-100 kJ/mol) a 10 °C rise near room temperature roughly doubles the rate. It is an empirical rule of thumb, and the effect grows stronger the higher Ea is.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
傅献彩 等,《物理化学》第5版,高等教育出版社,2005
Fu Xiancai et al., Physical Chemistry, 5th ed., Higher Education Press, 2005
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9787040167696（按标识回读: 物理化学(第五版)上册）
#阿伦尼乌斯 #活化能 #温度
什么是质量作用定律？
What is the law of mass action?
质量作用定律指出：在一定温度下，基元反应的反应速率与各反应物浓度的幂（幂次为化学计量数）成正比。由此可写出速率方程。对于复杂反应，总速率由最慢一步（决速步）决定。
The law of mass action states that at a fixed temperature, the rate of an elementary reaction is proportional to the product of reactant concentrations each raised to a power equal to its stoichiometric coefficient. This yields the rate law. For complex reactions, the overall rate is set by the slowest step (rate-determining step).
难度 进阶 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
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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。
Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）质量作用定律与速率方程章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (law of mass action; rate laws)
#质量作用定律 #速率方程 #决速步
勒夏特列原理是什么？
What is Le Chatelier's principle?
勒夏特列原理指出：当改变平衡体系的条件（浓度、温度、压力）时，平衡会向着减弱这种改变的方向移动。例如升温使吸热方向占优，加压使气体分子数减少的方向占优。它是预测平衡移动的核心规律。
Le Chatelier's principle states that when a condition of an equilibrium system (concentration, temperature, pressure) is changed, the equilibrium shifts in the direction that counteracts the change. For example, heating favors the endothermic direction and raising pressure favors the side with fewer gas molecules. It is the core rule for predicting equilibrium shifts.
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Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）化学平衡与勒夏特列原理章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (Le Chatelier's principle)
#勒夏特列 #平衡移动 #条件
为什么说燃烧是一种自由基链式反应？
Why is combustion described as a radical chain reaction?
以甲烷燃烧为例：高温或光使C-H键均裂产生自由基，这叫引发；随后CH3、HO、H等自由基相互反应，不断生成新的自由基，这叫链增长；最后自由基结合成稳定产物，叫链终止。反应通过活性中间体快速传递，速率极快并放出大量热。
In methane combustion, heat or light homolytically breaks C-H bonds to generate radicals - initiation. Radicals such as CH3, HO and H then react with each other to keep producing new radicals - propagation - until radicals combine into stable products - termination. The reaction races through reactive intermediates, proceeding rapidly and releasing much heat.
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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）
#链反应 #自由基 #燃烧
什么是决速步？
What is the rate-determining step?
在多步反应中，最慢的一步决定整个反应的速率，称为决速步（速率控制步）。它类似于瓶颈，总反应速率不超过该步速率。分析反应机理时常通过决速步推导实验速率方程。
In a multi-step reaction, the slowest step determines the overall rate and is called the rate-determining step. Like a bottleneck, the total rate cannot exceed that step's rate. Analyzing mechanisms often derives the experimental rate law from this step.
难度 进阶 · 适合 初中(12-15)
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Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）反应机理与决速步章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (reaction mechanisms; rate-determining step)
#决速步 #反应机理 #速率
反应的过渡态和反应中间体有什么本质区别？
What is the essential difference between a transition state and a reaction intermediate?
过渡态是反应坐标上能量最高的、无法分离的一瞬间构型，对应活化络合物；中间体是位于两个能垒之间的、能量相对较低的、可短暂存在甚至被检测到的物种。每步基元反应只有一个过渡态，而复杂反应可以经过多个中间体。
A transition state is the highest-energy, non-isolable configuration at a saddle point on the reaction coordinate (the activated complex), whereas an intermediate is a relatively low-energy species residing between two barriers that can exist transiently and sometimes be detected. Each elementary step has one transition state, but a complex reaction can pass through many intermediates.
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Atkins & de Paula《物理化学》（第10版），第22章反应动力学
Atkins & de Paula, "Physical Chemistry" (10th ed.), Ch.22
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL1907523W：Physical chemistry（首版 1
#过渡态 #反应中间体 #活化络合物 #势能面
什么是化学平衡常数？
What is the equilibrium constant?
化学平衡常数K是平衡时生成物浓度幂之积与反应物浓度幂之积的比值，各物质浓度以其化学计量数为指数。K只与温度有关，不随浓度或压力改变。K越大表示反应进行得越完全。
The equilibrium constant K is the ratio of the product of product concentrations (each raised to its stoichiometric coefficient) to that of reactants at equilibrium. K depends only on temperature, not on concentration or pressure. A larger K means the reaction proceeds more completely.
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Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）化学平衡常数章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (equilibrium constant)
#平衡常数 #浓度 #温度
为什么生产汽水时要往水里加压通入二氧化碳？松开瓶盖后为什么又不断冒泡？
Why is carbon dioxide forced into soda under high pressure, and why does opening the cap make it bubble endlessly?
气体在液体里的溶解度随压强增大而升高（亨利定律）。灌装时用高压把大量二氧化碳压进水里，开盖后瓶内压强骤降到大气压，溶解的二氧化碳变成过饱和状态，于是不断析出气泡。温度升高也会降低气体溶解度，所以热汽水跑气更快。这既是溶解平衡，也是气体分子从液体逸出的过程。
Gas solubility in a liquid rises with pressure (Henry's law). Filling machines use high pressure to force lots of carbon dioxide into the water; once the cap opens, the pressure inside drops to atmospheric, the dissolved gas becomes supersaturated, and bubbles stream out. Heat lowers gas solubility too, which is why warm soda goes flat faster. This is a dissolution equilibrium combined with gas molecules escaping the liquid.
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傅献彩 等,《物理化学》第5版,高等教育出版社,2005
Fu Xiancai et al., Physical Chemistry, 5th ed., Higher Education Press, 2005
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9787040167696（按标识回读: 物理化学(第五版)上册）
#亨利定律 #二氧化碳 #溶解平衡
拉瓦锡是怎么证明化学反应前后质量不变的？
How did Lavoisier prove mass is conserved in reactions?
他用密闭容器精确称量反应前后的总质量，发现没有物质凭空出现或消失，由此提出质量守恒。
Using sealed vessels, he weighed reactants and products precisely and found total mass unchanged, establishing conservation of mass.
难度 进阶 · 适合 初中(12-15)
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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
#拉瓦锡 #质量守恒 #历史
为什么臭氧层能吸收紫外线？
Why can the ozone layer absorb ultraviolet light?
臭氧分子（O3）能吸收波长200至320纳米的紫外辐射，吸收能量后分解为氧气和氧原子，随后又重新结合为臭氧。这一循环持续消耗有害的UV-B和UV-C，保护地表生物免受伤害。氟氯烃等物质会破坏这一平衡。
Ozone molecules (O3) absorb ultraviolet radiation at 200 to 320 nm; after absorbing energy they split into oxygen and an oxygen atom, then recombine into ozone. This cycle continuously removes harmful UV-B and UV-C, protecting surface life. Substances like CFCs disrupt this balance.
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Chapman, S. 《高层大气臭氧理论》，《Quarterly Journal of the Royal Meteorological Society》, 1930
Chapman, S. 'A Theory of Upper-Atmospheric Ozone,' Quarterly Journal of the Royal Meteorological Society, 1930, 56, 175–194
#臭氧层 #紫外线 #吸收
同样的煤，为什么碾成粉末后烧得更快、更旺？
Why does the same coal burn faster and more fiercely when ground into powder?
燃烧发生在煤与空气的接触界面上，接触面积越大，氧气越容易同时碰到更多碳原子，反应速率越快。煤粉的总表面积比同样质量的整块煤大几个数量级，所以点火更容易、燃烧更猛。火力发电厂把煤磨成粉喷入炉膛，目的正是用巨大的接触面积换取快速而充分的燃烧。
Combustion happens where coal meets air, so a larger contact area lets oxygen reach far more carbon atoms at once and the reaction speeds up. A powder has orders of magnitude more total surface area than the same lump, so it ignites easily and burns violently. Power plants grind coal into dust and blow it into the furnace precisely to buy fast, complete combustion with that huge surface area.
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
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傅献彩 等,《物理化学》第5版,高等教育出版社,2005
Fu Xiancai et al., Physical Chemistry, 5th ed., Higher Education Press, 2005
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9787040167696（按标识回读: 物理化学(第五版)上册）
#燃烧 #表面积 #反应速率
ΔG 和 ΔG° 有什么区别？判断一个反应能否自发为什么看 ΔG 而不是 ΔG°？
What is the difference between ΔG and ΔG°, and why does spontaneity depend on ΔG rather than ΔG°?
ΔG° 是标准状态（各物质活度为 1）下的吉布斯自由能变，是一个固定常数；而 ΔG = ΔG° + RT ln Q 还与实际反应商 Q 有关。只有 ΔG < 0 时反应才自发；即便 ΔG° > 0，只要 Q 足够小（反应物远多于产物），反应仍可正向进行。
ΔG° is the Gibbs free-energy change under standard conditions (unit activity) and is a fixed constant, while ΔG = ΔG° + RT ln Q also depends on the reaction quotient Q. Spontaneity requires ΔG < 0; even if ΔG° > 0, the reaction proceeds forward whenever Q is small enough (reactants in large excess).
难度 进阶 · 适合 初中(12-15)
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Atkins & de Paula《物理化学》（第10版），第4章
Atkins & de Paula, "Physical Chemistry" (10th ed.), Ch.4
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL1907523W：Physical chemistry（首版 1
#吉布斯自由能 #标准态 #反应商 #自发性
什么是化学计量数？
What is a stoichiometric coefficient?
化学计量数是化学方程式中各物质前的整数，表示反应按比例消耗或生成的分子（或摩尔）数目。它用于计算反应物与产物的量关系，并出现在平衡常数与速率方程的幂次中。配平方程式是定量化学计算的基础。
A stoichiometric coefficient is the integer before each substance in a chemical equation, indicating how many molecules (or moles) are consumed or produced proportionally. It is used to relate amounts of reactants and products and appears as the exponent in equilibrium constants and rate laws. Balancing equations is the basis of quantitative chemistry.
难度 进阶 · 适合 初中(12-15)
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Brown、LeMay、Bursten 等《化学：中心科学》（第14版，Pearson）化学计量章节
Brown, T. L.; LeMay, H. E.; Bursten, B. E.; et al. Chemistry: The Central Science, 14th ed., Pearson (stoichiometry)
独立核验依据 · Independent verification: 核验依据 1 ARCHIVE 标识 studentlectureno00theo：Chemistry, the central
#化学计量 #方程式 #配平
什么是活化能？
What is activation energy?
活化能是反应物分子转变为产物所需跨越的最低能量壁垒。只有能量达到或超过活化能的分子（活化分子）才能发生反应。催化剂通过提供新路径降低活化能，从而加快反应。
Activation energy is the minimum energy barrier that reactant molecules must cross to become products. Only molecules with energy at or above this level (activated molecules) can react. A catalyst lowers the activation energy by offering a new pathway, thus speeding the reaction.
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CC BY 4.0 · 已核验 · Verified 2026-08-23
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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
#活化能 #能量壁垒 #催化剂
催化剂对化学平衡有什么影响？
What effect does a catalyst have on chemical equilibrium?
催化剂同等降低正、逆反应的活化能，从而同等加快两个方向的速率。它能使体系更快达到平衡，但不会改变平衡的位置和各物质的平衡浓度。也就是说，催化剂只改变到达平衡的速度，不改变平衡常数。
A catalyst lowers the activation energy of both forward and reverse reactions equally, speeding up both rates by the same factor. It lets the system reach equilibrium faster but does not change the equilibrium position or the equilibrium concentrations. In short, a catalyst changes the speed of reaching equilibrium, not the equilibrium constant.
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Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）催化对平衡的影响章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (effect of catalyst on equilibrium)
#催化剂 #平衡 #活化能
化学平衡时反应真的"停止"了吗？反应物与生成物的浓度一定相等吗？
At chemical equilibrium has the reaction truly "stopped," and must reactant and product concentrations be equal?
平衡是动态平衡：正、逆反应速率相等，宏观浓度不再变化，但分子层面的反应仍在两个方向同时进行。平衡位置由平衡常数 K 决定，K 很大时产物占优、K 很小时反应物占优，两者浓度通常并不相等。
Equilibrium is dynamic: the forward and reverse rates are equal and concentrations are constant macroscopically, yet molecular reactions continue in both directions. The position is set by the equilibrium constant K—large K favors products, small K favors reactants—so the two concentrations are generally not equal.
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Brown, LeMay & Bursten《化学：中心科学》（第14版），第15章
Brown, LeMay & Bursten, "Chemistry: The Central Science" (14th ed.), Ch.15
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#化学平衡 #动态平衡 #平衡常数 #可逆反应
什么是反应速率？
What is reaction rate?
反应速率表示化学反应进行的快慢，通常用单位时间内反应物浓度减少或生成物浓度增加来衡量。速率受温度、浓度、压力和催化剂等因素影响。研究速率的学科称为化学动力学。
Reaction rate describes how fast a chemical reaction proceeds, usually measured by the decrease in reactant concentration or increase in product concentration per unit time. The rate is affected by factors such as temperature, concentration, pressure and catalysts. The study of rates is called chemical kinetics.
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Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）化学动力学章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (chemical kinetics)
#反应速率 #化学动力学 #浓度
什么是pH值？
What is pH value?
pH值是衡量溶液酸碱性的标度，等于氢离子浓度的负对数。pH为7表示中性，小于7为酸性，大于7为碱性。pH每相差1，氢离子浓度相差10倍。
pH is a scale measuring how acidic or basic a solution is; it equals the negative logarithm of the hydrogen ion concentration. A pH of 7 is neutral, below 7 is acidic and above 7 is basic. Each unit difference means a tenfold change in hydrogen ion concentration.
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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
#pH #酸碱 #氢离子
什么是化学平衡？
What is chemical equilibrium?
化学平衡指可逆反应中正、逆反应速率相等，各物质浓度不再随时间变化的状态。此时反应并未停止，而是动态平衡，正逆反应仍在进行。平衡可以从宏观上表现为体系性质恒定。
Chemical equilibrium is the state in a reversible reaction where the forward and reverse rates become equal and the concentrations of substances no longer change with time. The reaction has not stopped; it is a dynamic balance with both directions still occurring. Macroscopically, the system's properties appear constant.
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Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）化学平衡章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (chemical equilibrium)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787040193428（豆瓣书目条目: 物理化学）
#化学平衡 #可逆反应 #动态平衡
强酸和弱酸的区别是什么？
What is the difference between a strong acid and a weak acid?
强酸在水溶液中几乎完全电离，如盐酸、硫酸；弱酸只部分电离，存在电离平衡，如醋酸。因此相同浓度下强酸的氢离子浓度更高、酸性更强。弱酸的酸性强弱可用电离常数比较。
A strong acid ionizes almost completely in water, such as hydrochloric and sulfuric acid, while a weak acid ionizes only partially and establishes an ionization equilibrium, like acetic acid. So at the same concentration a strong acid yields a higher hydrogen ion concentration and is more acidic. The strength of weak acids is compared using ionization constants.
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Brown、LeMay、Bursten 等《化学：中心科学》（第14版，Pearson）酸碱平衡章节
Brown, T. L.; LeMay, H. E.; Bursten, B. E.; et al. Chemistry: The Central Science, 14th ed., Pearson (acid–base equilibria)
独立核验依据 · Independent verification: 核验依据 1 ARCHIVE 标识 studentlectureno00theo：Chemistry, the central
#强酸 #弱酸 #电离
温度如何影响反应速率？
How does temperature affect reaction rate?
一般情况下，温度升高会加快反应速率，因为更多分子获得超过活化能的能量。温度每升高约10摄氏度，许多反应的反应速率可翻倍。这一规律在食品保鲜和工业控制中非常重要。
Generally, raising the temperature speeds up a reaction because more molecules acquire energy above the activation energy. For many reactions, a rise of about 10 degrees Celsius can double the rate. This principle matters in food preservation and industrial process control.
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Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）温度对反应速率的影响与阿伦尼乌斯方程章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (temperature dependence of rate; Arrhenius equation)
#温度 #反应速率 #活化能
什么是电解质和非电解质？
What are electrolytes and non-electrolytes?
电解质是在水溶液中或熔融状态下能导电的化合物，如食盐、盐酸，因为它们能产生自由移动的离子。非电解质如蔗糖、乙醇，溶于水后仍以分子形式存在，不导电。电解质的强弱决定其导电能力。
An electrolyte is a compound that conducts electricity in aqueous solution or when molten, such as table salt and hydrochloric acid, because it produces freely moving ions. A non-electrolyte like sucrose or ethanol remains molecular in water and does not conduct. The strength of an electrolyte determines its conductivity.
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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
#电解质 #非电解质 #导电
什么是可逆反应？
What is a reversible reaction?
可逆反应是指在同一条件下既能向正方向进行、又能向逆方向进行的反应，常用可逆符号表示。绝大多数化学反应都具有一定的可逆性。可逆反应是建立化学平衡的前提。
A reversible reaction is one that can proceed in both the forward and reverse directions under the same conditions, often shown with a reversible arrow. Most chemical reactions have some reversibility. Reversible reactions are the basis for establishing chemical equilibrium.
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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。
Atkins 与 de Paula《物理化学》（第10版，牛津大学出版社）化学平衡与可逆反应章节
Atkins, P. W.; de Paula, J. Physical Chemistry, 10th ed., Oxford University Press (reversible reactions and equilibrium)
#可逆反应 #化学平衡 #反应方向