什么是熵？为什么孤立体系的熵总是趋向于增大？
What is entropy, and why does the entropy of an isolated system always tend to increase?
熵是体系微观状态数的度量，反映能量与粒子分布的混乱程度，统计表达为 S = k lnΩ。按热力学第二定律，孤立体系中的自发过程总是朝微观状态数更多、出现概率更大的方向进行，因此其熵只能增大或保持不变，仅在可逆极限下才不变。
Entropy measures the number of microstates and reflects disorder. By the second law, a spontaneous process in an isolated system moves toward more probable (more numerous microstate) states, so entropy does not decrease and is constant only in the reversible limit.
难度 专业 · 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）
#熵 #热力学第二定律 #微观状态
勒夏特列原理能否告诉我们平衡移动的程度或方向的热力学必然性？
Can Le Chatelier's principle tell us the extent or thermodynamic certainty of equilibrium shift?
勒夏特列原理只是定性经验：系统会抵抗外加扰动。它不能给出移动量，也非严格推导；精确的移动方向与程度必须由反应商 Q 与 K 的比较及范特霍夫方程等热力学关系决定。
Le Chatelier's principle is qualitative: a system resists perturbation. It gives no magnitude and is not a rigorous derivation; the exact direction and extent come from comparing Q with K and thermodynamic relations like the van't Hoff equation.
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
Atkins, de Paula, Keeler,《Atkins' Physical Chemistry》第11版,Oxford University Press,2018
P. Atkins, J. de Paula and J. Keeler, Atkins' Physical Chemistry, 11th ed., Oxford University Press, 2018
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-19-884781-6 (11th ed., Oxford University Pres
#平衡 #勒夏特列 #热力学
为什么有些反应升温后速率反而下降（负温度系数）？这与活化能概念矛盾吗？
Why do some reactions slow down when heated (negative temperature coefficient), and does this contradict the activation-energy concept?
这类反应往往是多步且有放热预平衡（如 NO 氧化），升温使平衡常数减小、关键中间体浓度下降，整体表观速率下降。这并不否定阿伦尼乌斯关系，而是表观速率常数由多个步骤常数组合而成，需区分基元与表观活化能。
Such reactions are usually multistep with an exothermic pre-equilibrium (for example the oxidation of NO); heating lowers that equilibrium constant and the concentration of the key intermediate, so the overall apparent rate falls. This does not contradict the Arrhenius relation: the apparent rate constant is a composite of several elementary rate constants, so the apparent activation energy can be negative even when every elementary step has a positive one.
难度 专业 · 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）
#负温度系数 #预平衡 #表观速率
阿伦尼乌斯方程中指前因子 A 和活化能 Ea 分别反映反应的什么性质？如何由实验数据求它们？
In the Arrhenius equation, what do the pre-exponential factor A and activation energy Ea reflect, and how are they obtained from data?
活化能 Ea 是反应物越过能垒所需的最低能量，决定温度对速率的敏感程度；指前因子 A 反映碰撞频率与空间取向等概率因素。对 ln k 对 1/T 作图（阿伦尼乌斯图），斜率给出 −Ea/R，截距给出 ln A。
The activation energy Ea is the minimum energy to cross the barrier and governs how sharply rate responds to temperature; the pre-exponential factor A reflects collision frequency and orientation probability. Plotting ln k versus 1/T (an Arrhenius plot) gives slope −Ea/R and intercept ln A.
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）
#阿伦尼乌斯方程 #活化能 #指前因子
吉布斯自由能如何判断反应自发性？
How does Gibbs free energy predict reaction spontaneity?
ΔG = ΔH − TΔS；当 ΔG < 0 时反应在恒温恒压下自发。它把焓变与熵变统一：放热且增熵最有利，吸热但强增熵在较高温度也可自发。
ΔG = ΔH − TΔS; a reaction is spontaneous at constant T and P when ΔG < 0. It unifies enthalpy and entropy: exothermic plus entropy-increasing is favorable, while an endothermic reaction can still be spontaneous if entropy gain is large at high T.
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
Atkins, de Paula, Keeler,《Atkins' Physical Chemistry》第11版,Oxford University Press,2018
P. Atkins, J. de Paula and J. Keeler, Atkins' Physical Chemistry, 11th ed., Oxford University Press, 2018
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-19-884781-6 (11th ed., Oxford University Pres
#吉布斯自由能 #自发性 #熵
为什么有些吸热反应仍能自发进行？
Why can some endothermic reactions still be spontaneous?
自发性由 ΔG = ΔH − TΔS 决定。若熵增足够大（ΔS > 0），在较高温度下 TΔS 项可超过正的 ΔH，使 ΔG < 0，例如硝酸铵溶于水吸热却自发。
Spontaneity follows ΔG = ΔH − TΔS. If entropy increases enough (ΔS > 0), at high T the TΔS term can outweigh positive ΔH, making ΔG < 0—as when NH₄NO₃ dissolves endothermically yet spontaneously.
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
Atkins, de Paula, Keeler,《Atkins' Physical Chemistry》第11版,Oxford University Press,2018
P. Atkins, J. de Paula and J. Keeler, Atkins' Physical Chemistry, 11th ed., Oxford University Press, 2018
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-19-884781-6 (11th ed., Oxford University Pres
#熵 #自发性 #溶解
平衡常数 K 与标准吉布斯自由能变 ΔG° 之间是什么关系？
What is the relationship between the equilibrium constant K and the standard Gibbs free energy change ΔG°?
二者由 ΔG° = −RT ln K 联系：ΔG° 越负，平衡常数越大，反应在标准态下越偏向产物。该式把热力学判据与平衡位置定量地统一起来。
They are linked by ΔG° = −RT ln K: the more negative ΔG°, the larger K, and the more the reaction favors products under standard conditions. This equation quantitatively unifies the thermodynamic criterion with equilibrium position.
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）
#平衡常数 #吉布斯自由能 #热力学
勒夏特列原理（平衡移动原理）说的是什么？举一个应用例子。
What does Le Chatelier's principle state, and give an application example.
勒夏特列原理指出，若改变平衡体系的温度、压力或浓度，体系会自发向减弱该改变的方向移动。例如合成氨中增大压力、移走产物氨，都能促使平衡向生成氨的方向移动。
Le Chatelier's principle states that when a system at equilibrium is disturbed by a change in temperature, pressure, or concentration, it shifts in the direction that partly counteracts the disturbance. For example, in ammonia synthesis raising the pressure or continuously removing ammonia both shift the equilibrium toward more ammonia.
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）
#勒夏特列原理 #化学平衡 #合成氨
什么是反应级数？它和反应的分子数一定相同吗？
What is reaction order, and is it necessarily the same as the molecularity of the reaction?
反应级数是速率方程中各物质浓度幂次的总和，由实验测定。分子数是基元反应中同时碰撞的反应物粒子数，仅对基元反应有意义。对复杂反应，反应级数可以是分数或零，与分子数并不一致。
Reaction order is the sum of concentration exponents in the rate law, determined experimentally. Molecularity is the number of particles colliding simultaneously in an elementary step and applies only to elementary reactions. For complex reactions the order can be fractional or zero and need not equal molecularity.
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）
#反应级数 #分子数 #速率方程
什么是催化剂？它如何影响化学反应速率而自身不被消耗？
What is a catalyst, and how does it speed up a reaction without being consumed?
催化剂是能改变反应速率而在反应前后化学性质和数量不变的物质。它通过提供新路径、降低活化能来加快正逆反应，但不改变平衡常数与反应焓变，反应结束后可复原。
A catalyst changes the reaction rate while retaining its chemical identity and amount after the reaction. It offers an alternative pathway with lower activation energy, accelerating both forward and reverse rates without altering the equilibrium constant or enthalpy; it is recovered unchanged.
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）
#催化剂 #活化能 #反应路径
过渡态理论（绝对反应速率理论）用什么量来描述反应速率？活化络合物是什么意思？
What quantity does transition-state theory use to describe reaction rate, and what is an activated complex?
过渡态理论用活化络合物（位于势能面鞍点、与反应物近似平衡）的浓度及其越过势垒的频率 ν 来表达速率。活化络合物是反应物在转化为产物途中、键部分断裂又部分形成的瞬时高能量构型。
Transition-state theory expresses the rate via the concentration of the activated complex (at the saddle point of the potential energy surface, in quasi-equilibrium with reactants) and its frequency ν of crossing the barrier. The activated complex is the transient, high-energy configuration midway between reactants and products with bonds partly broken and formed.
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。
《物理化学》(傅献彩) 第五版 上册 第 10 章 ; 另见: H. Eyring, J. Chem. Phys. 1935, 3, 107 (AIP)
H. Eyring, J. Chem. Phys. 1935, 3, 107 (AIP) ; see also: 《物理化学》(傅献彩) 第五版 上册 第 10 章
#过渡态理论 #活化络合物 #势能面
比热容大意味着什么？
What does a large specific heat capacity mean?
比热容大表示单位质量升高 1℃ 需吸收更多热量，温度变化慢。水的比热容很高，因此海洋调节气候、人体靠水维持体温稳定都与此有关。
A large specific heat means more energy is needed per unit mass to raise temperature by 1°C, so temperature changes slowly. Water's high specific heat lets oceans buffer climate and the body stabilize temperature.
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
Atkins, de Paula, Keeler,《Atkins' Physical Chemistry》第11版,Oxford University Press,2018
P. Atkins, J. de Paula and J. Keeler, Atkins' Physical Chemistry, 11th ed., Oxford University Press, 2018
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-19-884781-6 (11th ed., Oxford University Pres
#比热容 #热量 #水
平衡常数的大小说明什么？
What does the magnitude of an equilibrium constant indicate?
K 很大（≫1）表示平衡强烈偏向生成物，反应进行得“完全”；K 很小（≪1）表示主要剩反应物。K 只告诉平衡组成，不说明到达平衡的快慢。
A large K (≫1) means equilibrium favors products and the reaction goes nearly to completion; a small K (≪1) means mostly reactants remain. K only tells the equilibrium composition, not how fast it is reached.
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
Atkins, de Paula, Keeler,《Atkins' Physical Chemistry》第11版,Oxford University Press,2018
P. Atkins, J. de Paula and J. Keeler, Atkins' Physical Chemistry, 11th ed., Oxford University Press, 2018
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-19-884781-6 (11th ed., Oxford University Pres
#平衡常数 #反应程度 #产物
勒夏特列原理说的是什么？
What does Le Chatelier's principle state?
当改变平衡系统的条件（浓度、压力、温度）时，系统会自发向减弱该改变的方向移动。例如增大反应物浓度，平衡正向移动以消耗多余反应物。
When you change conditions (concentration, pressure, temperature) of an equilibrium, the system shifts to counteract that change. For example, adding reactant drives the equilibrium forward to consume the excess.
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
Atkins, de Paula, Keeler,《Atkins' Physical Chemistry》第11版,Oxford University Press,2018
P. Atkins, J. de Paula and J. Keeler, Atkins' Physical Chemistry, 11th ed., Oxford University Press, 2018
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-19-884781-6 (11th ed., Oxford University Pres
#勒夏特列 #平衡移动 #扰动