标准吉布斯自由能变ΔG°与化学平衡常数K之间有什么关系？如何用ΔG°判断反应方向？
What is the relationship between the standard Gibbs free energy change ΔG° and the equilibrium constant K, and how is ΔG° used to predict reaction direction?
二者满足 ΔG° = −RT·ln K（R为气体常数、T为热力学温度），因此K = e^(−ΔG°/RT)。若ΔG° < 0则K > 1、反应在标准态下正向自发；若ΔG° > 0则K < 1、正向非自发。
They are related by ΔG° = −RT·ln K (R the gas constant, T the absolute temperature), so K = e^(−ΔG°/RT). If ΔG° < 0 then K > 1 and the reaction is spontaneous in the forward direction under standard conditions; if ΔG° > 0 then K < 1 and the forward direction is non-spontaneous.
难度 专业 · 适合 高中(15-18)
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）
#吉布斯自由能 #平衡常数 #自发 #热力学 #ΔG
为什么自由能而非单纯放热决定反应能否自发？
Why does free energy, not just heat release, decide spontaneity?
吉布斯自由能 ΔG = ΔH − TΔS 同时计入焓与熵，只有 ΔG<0 的过程在恒温恒压下才自发。看似吸热的溶解或结晶有时也能自发，正是因为熵增抵消了焓的不利。吉布斯 1876 年确立了这一判据。
Gibbs free energy ΔG = ΔH − TΔS combines enthalpy and entropy; only ΔG<0 makes a process spontaneous at constant T and P. Some endothermic dissolutions still occur because entropy gain outweighs the enthalpy penalty. Gibbs established this criterion in 1876.
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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J. W. Gibbs,《On the Equilibrium of Heterogeneous Substances》, 康涅狄格艺术与科学学院院刊, 1876; Atkins & de Paula《物理化学》
J. W. Gibbs, On the Equilibrium of Heterogeneous Substances, Trans. Conn. Acad. Arts Sci., 1876; Atkins & de Paula, Physical Chemistry
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 #自发 #熵
什么是蒸气压？拉乌尔定律说什么？
What is vapor pressure and what does Raoult's law state?
蒸气压是液体（或固体）与其蒸气在平衡时的压强，反映物质挥发的难易，随温度升高而增大。拉乌尔定律指出，理想溶液中溶剂的蒸气压等于纯溶剂蒸气压乘以它的摩尔分数。该定律是依数性（如沸点升高）的基础。
Vapor pressure is the pressure of a vapor in equilibrium with its liquid or solid, reflecting how readily a substance evaporates; it rises with temperature. Raoult's law states that in an ideal solution the solvent's vapor pressure equals the pure solvent's vapor pressure times its mole fraction. This law underlies colligative properties like boiling-point elevation.
难度 专业 · 适合 高中(15-18)
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）
#蒸气压 #拉乌尔定律 #理想溶液
动力学控制与热力学控制有什么区别？
What is the difference between kinetic and thermodynamic control?
低温或短时反应受活化能主导，产物由最快路径决定（动力学控制）；高温或长时间则体系趋向最稳定的产物（热力学控制）。Diels-Alder 与烯醇化常用来展示这种产物分布的反转。
At low temperature or short time the product is set by the fastest path—kinetic control; at high temperature or long time the system favors the most stable product—thermodynamic control. Diels-Alder and enolization commonly show this product switch.
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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Carey 与 Sundberg《高等有机化学》；Atkins《物理化学》
Carey & Sundberg, Advanced Organic Chemistry; Atkins, Physical Chemistry
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL489216W：Advanced organic chemist
#动力学控制 #热力学控制 #产物分布
为什么往溶液里加盐会降低它的冰点？
Why does adding salt lower a solution's freezing point?
溶质粒子降低了溶剂的蒸气压，使固液平衡温度下移，这就是依数性中的凝固点降低；降低幅度正比于溶质粒子浓度（Raoult 定律）。道路除冰撒盐正是利用这一原理。
Solute particles lower the solvent's vapor pressure, shifting the solid-liquid balance to a lower temperature—freezing-point depression, a colligative property proportional to solute particle concentration (Raoult's law). Spreading salt on roads exploits exactly this.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
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拉乌尔 1882 年论文；Atkins《物理化学》
Raoult (1882); Atkins, Physical Chemistry
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#凝固点降低 #依数性 #拉乌尔定律
活化能是什么，阿伦尼乌斯方程描述了什么？
What is activation energy, and what does the Arrhenius equation describe?
活化能是反应物翻越能垒到达过渡态所需的最低额外能量；阿伦尼乌斯方程 k=Ae^(−Ea/RT) 表明速率常数随温度升高或 Ea 降低而指数增长。阿伦尼乌斯 1889 年提出该式并解释了温度对反应速率的影响。
Activation energy is the extra energy reactants need to reach the transition state; the Arrhenius equation k=Ae^(−Ea/RT) shows the rate constant rises exponentially with temperature or lower Ea. Arrhenius proposed it in 1889 to explain temperature effects.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
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阿伦尼乌斯 1889 年论文；Atkins《物理化学》
Arrhenius (1889); Atkins, Physical Chemistry
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#活化能 #阿伦尼乌斯 #反应速率
真实气体为什么偏离理想气体定律？
Why do real gases deviate from the ideal gas law?
理想气体假设分子无体积且无力作用；真实分子有有限体积并产生范德华吸引，高压低温下尤为明显。范德华 1873 年用 (P+a/V²)(V−b)=RT 修正，因此获 1910 年诺奖。
The ideal gas assumes point particles with no forces; real molecules have finite volume and attract one another, deviations that grow at high pressure and low temperature. van der Waals corrected this in 1873 with (P+a/V²)(V−b)=RT, earning the 1910 Nobel Prize.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
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范德华 1873 年论文；Atkins《物理化学》
van der Waals (1873); Atkins, Physical Chemistry
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL1907523W：Physical chemistry（首版 1
#范德华方程 #真实气体 #非理想性
水的三相点是什么？它和国际温标有什么关系？
What is the triple point of water, and what is its relation to the international temperature scale?
水的三相点是纯水固、液、气三相平衡共存的唯一状态，温度为0.01℃（273.16 K）、压力为611.657帕。它被选定为热力学温标（开尔文）的定义固定点，即规定该点温度精确为273.16 K，是温度计量的基准。
The triple point of water is the unique state where pure water's solid, liquid, and vapor phases coexist in equilibrium, at 0.01 ℃ (273.16 K) and 611.657 Pa. It is designated as the defining fixed point of the thermodynamic temperature scale (kelvin), fixed exactly at 273.16 K, and serves as a primary reference for thermometry.
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
#三相点 #水 #热力学温标 #开尔文 #相平衡
热力学第二定律关于熵说了什么？为什么冰融化、气体扩散这类过程会自发发生？
What does the second law of thermodynamics say about entropy, and why do processes like ice melting or gas spreading out happen spontaneously?
热力学第二定律指出，孤立系统的总熵（混乱度的度量）不会减少，自发过程趋向于使总熵增加。冰融化和气体扩散都使分子排列更加无序、系统熵增大，因此在常温常压下能够自发进行。
The second law of thermodynamics states that the total entropy (a measure of disorder) of an isolated system never decreases, and spontaneous processes tend to increase total entropy. Both ice melting and gas diffusion increase molecular disorder and thus system entropy, so they proceed spontaneously at ordinary temperature and pressure.
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
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）
#熵 #热力学第二定律 #自发 #混乱度 #孤立系统
阿伦尼乌斯方程（Arrhenius equation）表达了什么关系？活化能Ea代表什么？
What relationship does the Arrhenius equation express, and what does the activation energy Ea represent?
阿伦尼乌斯方程 k = A·e^(−Ea/RT) 描述了反应速率常数k随温度T指数上升的关系，其中A为指前因子、R为气体常数。活化能Ea是反应物分子跨越能垒、转变为产物所需的最低能量，Ea越大反应对温度越敏感、速率越慢。
The Arrhenius equation, k = A·e^(−Ea/RT), describes how the rate constant k rises exponentially with temperature T, where A is the pre-exponential factor and R the gas constant. The activation energy Ea is the minimum energy reactant molecules must overcome to form products; a larger Ea makes the reaction more temperature-sensitive and slower.
难度 进阶 · 适合 高中(15-18)
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）
#阿伦尼乌斯方程 #活化能 #速率常数 #温度 #指前因子
物质的相变中潜热是什么？
What is latent heat in a phase change?
潜热是在温度不变的情况下，物质发生相变（如熔化、汽化）时吸收或放出的热量。例如冰在 0℃ 熔化成水要吸收熔化热，但温度不升高。潜热用于克服分子间作用力而非提高分子动能。
Latent heat is the heat absorbed or released during a phase change such as melting or vaporization at constant temperature. Ice at 0°C absorbs the heat of fusion to become water without its temperature rising. Latent heat overcomes intermolecular forces rather than raising molecular kinetic energy.
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
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）
#潜热 #相变 #熔化热
什么是溶液的依数性？举一个例子。
What are colligative properties of solutions? Give an example.
依数性是指只取决于溶质粒子数目、而与溶质种类无关的性质，包括沸点升高、凝固点降低、渗透压和蒸气压下降。例如在冰雪上撒盐，盐粒降低了水的凝固点，使冰在 0℃ 以下融化。海水凝固点低于纯水也是同一原理。
Colligative properties depend only on the number of solute particles, not their identity; they include boiling-point elevation, freezing-point depression, osmotic pressure, and vapor-pressure lowering. Spreading salt on ice lowers water's freezing point so it melts below 0°C. Seawater also freezes below 0°C for the same reason.
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
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）
#依数性 #凝固点降低 #渗透压
什么是熵？它如何判断过程能否自发？
What is entropy and how does it tell if a process is spontaneous?
熵是体系混乱度（微观状态数）的度量，单位为 J·K⁻¹·mol⁻¹。热力学第二定律指出孤立体系的熵永不减少，等温等压下可用吉布斯自由能 ΔG = ΔH – TΔS 判断：ΔG<0 时过程自发。熵增常伴随扩散、混合和气体生成。
Entropy measures a system's disorder (number of microstates), with units J·K⁻¹·mol⁻¹. The second law states the entropy of an isolated system never decreases; at constant T and p, Gibbs free energy ΔG = ΔH – TΔS decides spontaneity: if ΔG<0 the process is spontaneous. Entropy increases with spreading, mixing, and gas formation.
难度 进阶 · 适合 高中(15-18)
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）
#熵 #热力学第二定律 #吉布斯自由能
什么是焓？焓变与反应放热有何关系？
What is enthalpy and how is the enthalpy change linked to heat release?
焓（H）是体系的内能加压强体积项（H = U + pV），在等压条件下的变化 ΔH 约等于吸收或放出的热量。ΔH<0 为放热反应，ΔH>0 为吸热反应。燃烧、中和多为放热，而分解、汽化多为吸热。
Enthalpy (H) is a system's internal energy plus a pressure–volume term (H = U + pV); at constant pressure its change ΔH roughly equals heat absorbed or released. ΔH<0 means an exothermic reaction, ΔH>0 an endothermic one. Combustion and neutralization are typically exothermic, decomposition and vaporization endothermic.
难度 进阶 · 适合 高中(15-18)
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）
#焓 #焓变 #放热反应
布朗斯特—劳里酸碱理论如何定义酸和碱？它比阿伦尼乌斯理论好在哪里？
How do the Brønsted-Lowry definitions characterize acids and bases, and what advantage do they have over the Arrhenius concept?
布朗斯特—劳里理论把酸定义为质子（H⁺）的给予体、碱定义为质子的接受体，酸碱反应本质上是质子转移。它突破了水溶液的限制，能够解释氨（NH3）在非水体系中的碱性以及如NH4⁺这类共轭酸，适用范围比仅限水溶液的阿伦尼乌斯理论更广。
The Brønsted-Lowry concept defines an acid as a proton (H⁺) donor and a base as a proton acceptor, with acid-base reactions being proton transfer. It is not limited to aqueous solution, so it explains the basicity of ammonia (NH3) and species like the conjugate acid NH4⁺, giving it a broader scope than the water-limited Arrhenius definition.
难度 入门 · 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
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）
#布朗斯特—劳里 #酸碱 #质子 #共轭 #酸碱理论
理想气体状态方程是什么？各量代表什么？
What is the ideal gas law and what do its variables mean?
理想气体状态方程为 pV = nRT，其中 p 是压强、V 是体积、n 是物质的量、T 是热力学温度、R 是理想气体常数。它把气体的宏观状态量联系起来，是低压高温下真实气体的良好近似。压力、体积、温度、物质的量四者中已知三个即可求第四个。
The ideal gas law is pV = nRT, where p is pressure, V is volume, n is amount of substance, T is thermodynamic temperature, and R is the ideal gas constant. It links a gas's macroscopic state variables and approximates real gases well at low pressure and high temperature. Knowing any three of p, V, T, n gives the fourth.
难度 入门 · 适合 小学低段(6-8)
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）
#理想气体 #状态方程 #气体常数
为什么用肥皂洗手能把油乎乎的脏东西洗掉？
Why does washing with soap remove greasy dirt from your hands?
肥皂分子一头喜欢水、一头喜欢油，能把大油滴包成小油珠分散在水里，这个过程叫乳化。被肥皂包起来的油污就随水冲走了，所以手就干净了。
Soap molecules have one end that loves water and one end that loves oil, so they wrap greasy droplets into tiny drops that spread out in water—a process called emulsification. The oil trapped by soap is then rinsed away with the water, leaving hands clean.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
英国皇家化学会（RSC）化学实验与教育资源；Rosen & Kunjappu《表面活性剂与界面现象》（Surfactants and Interfacial Phenomena, Wiley）
Royal Society of Chemistry (RSC) experiments and education; M. J. Rosen & J. Kunjappu, 'Surfactants and Interfacial Phenomena' (Wiley)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-118-22902-6 (2012, Wiley)
#肥皂 #乳化 #表面活性剂 #油污
pH 和 pKa 到底在衡量什么？
What do pH and pKa actually measure?
pH = −log[H⁺] 衡量溶液的酸碱程度；pKa = −log Ka 衡量一个酸解离出质子的倾向，pKa 越小酸越强。Sørensen 在 1909 年引入 pH 概念，后来成为生物与化学的基础标度。
pH = −log[H⁺] measures how acidic or basic a solution is; pKa = −log Ka measures an acid's tendency to donate a proton, with smaller pKa meaning stronger acid. Sørensen introduced pH in 1909, now a foundational scale in chemistry and biology.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Sørensen 1909 年论文；Atkins《物理化学》
Sørensen (1909); Atkins, Physical Chemistry
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL1907523W：Physical chemistry（首版 1
#pH #pKa #酸解离