胶体为什么有时稳定、有时聚沉？
Why are colloids sometimes stable and sometimes coagulate?
DLVO 理论认为范德华吸引与双电层排斥相互竞争；加入电解质压缩双电层，就会聚沉。
DLVO theory balances van der Waals attraction against double-layer repulsion; adding electrolyte compresses the double layer and causes coagulation.
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
#DLVO #胶体 #聚沉
为什么有些油漆久放变稠一搅又稀，淀粉水却相反？
Why do some paints thicken at rest but thin when stirred, while starch water does the opposite?
油漆常具触变性，静置时结构形成变稠，搅动破坏结构变稀（可逆）；而玉米淀粉糊是剪切增稠，越搅越稠，机制相反。
Many paints are thixotropic: structure rebuilds at rest (thick), shearing breaks it (thin), reversibly. Cornstarch is shear-thickening—opposite behavior.
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）
#触变 #剪切 #流变
为什么极细的金颗粒分散在玻璃里会呈现红色（红宝石玻璃）？
Why do tiny gold particles in glass produce red (ruby glass)?
把极细的金纳米颗粒（直径约几十纳米）分散在玻璃中，会形成胶体。金纳米颗粒对特定波长的可见光产生表面等离子体共振，强烈吸收绿光并散射红光，于是玻璃整体呈现深红（宝石红）。颜色取决于颗粒大小、形状和浓度——这是“胶体金”的纳米尺度光学效应，而非金的本体黄色。
Tiny gold nanoparticles (tens of nanometers across) dispersed in glass form a colloid. They exhibit surface plasmon resonance, strongly absorbing green light and scattering red, so the glass as a whole looks deep ruby red. The exact hue depends on particle size, shape, and concentration. The color is a nanoscale optical effect of colloidal gold, not the bulk yellow of the metal itself.
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）
#金 #胶体 #颜色
胶束和临界胶束浓度（CMC）是什么？
What are micelles and the critical micelle concentration (CMC)?
表面活性剂超过 CMC 后自组装成疏水核、亲水壳的胶束，可增溶油污；CMC 是开始成胶束的阈值。
Above the CMC, surfactants self-assemble into micelles with hydrophobic cores and hydrophilic shells that solubilize grease; CMC is the threshold for micelle formation.
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
#胶束 #CMC #表面活性剂
为什么手工做肥皂最后要加盐水？
Why is salt water added at the end of soap making?
皂化得到脂肪酸钠和甘油的混合液，加高浓度盐使肥皂盐析析出，与甘油盐水分离，便于成型。
Saponification yields sodium fatty acid + glycerol; adding concentrated salt salts out the soap, separating it from the glycerol brine for shaping.
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）
#盐析 #肥皂 #皂化
圆珠笔油为什么写着写着就干？
Why does ballpoint-pen ink dry as you write?
油墨靠溶剂挥发和触变性(受剪切变稀)控制流动，写在纸上溶剂很快跑掉，于是固化不晕开。
The ink relies on solvent evaporation and shear-thinning; on paper the solvent quickly escapes, so it sets without smearing.
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）
#圆珠笔 #油墨 #触变
为什么番茄酱瓶倒扣拍几下才流下来？
Why does ketchup flow only after you tap the bottle?
番茄酱是剪切变稀的非牛顿流体：静止时黏稠难流，受到拍打震动后黏度下降，才容易倒出，与玉米淀粉糊正好相反。
Ketchup is shear-thinning: at rest it's viscous, but shaking/shearing lowers viscosity so it flows—opposite of oobleck.
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）
#番茄酱 #剪切变稀 #非牛顿
向Fe(OH)3正溶胶中加入少量Na2SO4比加入等物质的量的NaCl更容易使其聚沉,请解释原因。
Adding a small amount of Na2SO4 precipitates a positively charged Fe(OH)3 sol far more readily than the same molar amount of NaCl. Explain why.
溶胶聚沉主要取决于与胶粒电荷符号相反的电解质离子,其价数越高聚沉能力越强,即Schulze–Hardy规则。SO4^2−是二价反离子,对正电Fe(OH)3胶粒的聚沉值远低于一价的Cl−,通常低一到两个数量级。因此相同摩尔浓度下硫酸钠的聚沉效果显著强于氯化钠,体现了反离子价态的决定性影响。
Coagulation of a sol is governed mainly by counterions of opposite sign to the particle charge, and their effectiveness rises sharply with valence — the Schulze–Hardy rule. Sulfate is divalent, so for positively charged Fe(OH)3 particles its critical coagulation concentration is one to two orders of magnitude lower than that of monovalent chloride. Hence equimolar Na2SO4 coagulates the sol much more readily than NaCl, demonstrating the decisive role of counterion valence.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
沈钟、赵振国《胶体与表面化学》第三版第四章溶胶的电学性质与聚沉
Shen Zhong & Zhao Zhenguo, Colloid and Surface Chemistry, 3rd ed., Chapter 4 (electrical properties and coagulation of sols)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787502555764（豆瓣书目条目: 胶体与表面化学）
#聚沉 #Schulze-Hardy规则
为什么牛奶是乳浊液而豆浆放置后容易分层?从胶体稳定性的角度解释两者体系的差别。
Why does milk remain a stable emulsion while soy milk tends to separate on standing? Explain the difference from the perspective of colloid stability.
牛奶中的脂肪球被天然乳化剂——磷脂和蛋白质膜包裹,形成带电荷的水化层,通过静电排斥和空间位阻抑制聚结,体系长期稳定。豆浆的蛋白质颗粒主要靠双电层静电排斥维持分散,pH 接近等电点或加热使蛋白变性聚集时,排斥势垒降低,颗粒迅速絮凝沉降。因此两者的差异本质在于界面保护层的组成与稳定性不同。
Fat globules in milk are coated by natural emulsifiers — phospholipids and protein membranes — that form hydrated charged layers; electrostatic repulsion plus steric hindrance suppresses coalescence, keeping the emulsion stable. Soy milk particles rely mainly on double-layer electrostatic repulsion, so near the isoelectric point or after heat denaturation the repulsive barrier drops and the particles flocculate and settle. The difference lies in the composition and robustness of each interfacial protective layer.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
P. C. Hiemenz & R. Rajagopalan,《Principles of Colloid and Surface Chemistry》第2版,Marcel Dekker,1997
Hiemenz & Rajagopalan, Principles of Colloid and Surface Chemistry, 2nd ed., Marcel Dekker, 1997
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-8247-7476-9 (1997, Marcel Dekker)
#胶体与界面化学 #乳化稳定机制
向Fe(OH)3溶胶中加入少量电解质就会迅速聚沉:请用DLVO理论解释总相互作用能曲线、排斥能垒与临界聚沉浓度的关系,并说明Schulze-Hardy规则的含义。
Adding a small amount of electrolyte rapidly coagulates an Fe(OH)3 sol. Use DLVO theory to relate the total interaction energy curve and its repulsive barrier to the critical coagulation concentration, and state what the Schulze-Hardy rule says.
DLVO理论将范德华吸引势能与双电层重叠导致的静电排斥势能叠加,得到粒子间总相互作用能曲线;当排斥能垒远高于热运动动能时,布朗运动带来的碰撞无法逾越能垒,溶胶处于动力学稳定状态。升高电解质浓度会压缩扩散双电层、使zeta电位绝对值减小,能垒随之降低直至消失,粒子坠入初级极小并发生不可逆聚沉,恰好消除能垒所对应的浓度即临界聚沉浓度(CCC)。Schulze-Hardy经验规律指出,起决定作用的是与胶粒电性相反的反离子,且CCC大致随反离子价态的六次方急剧下降。
DLVO theory sums van der Waals attraction with the electrostatic repulsion produced by overlapping double layers into a total interaction energy curve; while the repulsive barrier greatly exceeds thermal kinetic energy, collisions driven by Brownian motion cannot cross it and the sol stays kinetically stable. Increasing the electrolyte concentration compresses the diffuse double layer and shrinks the magnitude of the zeta potential, lowering the barrier until it disappears; particles then fall into the primary minimum and coagulate irreversibly, and the concentration at which the barrier vanishes is the critical coagulation concentration (CCC). The empirical Schulze-Hardy rule adds that counterions opposite in charge dominate the effect, and CCC drops steeply, roughly with the sixth power of counterion valence.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Derjaguin & Landau, Acta Physicochimica URSS 1941, 14: 633-662; Verwey & Overbeek, Theory of the Stability of Lyophobic Colloids, Elsevier, 1948
Derjaguin & Landau, Acta Physicochim. URSS 1941, 14, 633-662; Verwey & Overbeek, Theory of the Stability of Lyophobic Colloids, Elsevier, 1948
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL85937W：Theory of the stability o
#DLVO理论 #临界聚沉浓度
肥皂为什么能洗掉油污,而单用清水却不行?
Why can soap wash grease away while plain water cannot?
油与水互不相溶,纯水又无法降低油污与织物之间的界面张力,所以洗不掉。肥皂分子一端亲水、一端亲油,会吸附在油水界面并把亲油尾插入油滴,使油滴容易被机械作用从表面卷离;浓度超过临界胶束浓度后,分子聚成胶束把油包裹成稳定乳液随水冲走,油污便被清除。
Oil and water do not mix, and pure water cannot lower the interfacial tension that holds grease onto fabric, so rinsing alone fails. A soap molecule has a water-loving head and an oil-loving tail; it adsorbs at the oil-water interface with its tail buried in the droplet, letting agitation roll the grease off the surface. Once the concentration passes the critical micelle concentration, the molecules cluster into micelles that swallow the oil into a stable emulsion carried away by the rinse water.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
P. C. Hiemenz、R. Rajagopalan《Principles of Colloid and Surface Chemistry》,Marcel Dekker,1997
P. C. Hiemenz & R. Rajagopalan, Principles of Colloid and Surface Chemistry, Marcel Dekker, 1997
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-8247-7476-9 (1997, Marcel Dekker)
#表面活性剂 #胶束 #界面张力
什么是胶体？丁达尔效应是什么？
What is a colloid and what is the Tyndall effect?
胶体是分散相粒子直径约 1–100 nm 的分散体系，介于溶液与悬浊液之间，如牛奶、雾、豆浆。当一束光穿过胶体，粒子散射光形成可见光路，称为丁达尔效应，可用来区分胶体与真溶液。胶体因高比表面而性质活跃。
A colloid is a dispersion with particles about 1–100 nm in size, between true solutions and suspensions—milk, fog, and soy milk are examples. A light beam passing through scatters off particles, showing a visible path called the Tyndall effect, which distinguishes colloids from true solutions. Colloids are active because of their high 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
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）
#胶体 #丁达尔效应 #分散系
ζ 电位怎么衡量胶体稳定性？
How does zeta potential measure colloid stability?
ζ 电位是滑移面处的电势，绝对值越大颗粒间互斥越强、越稳定；接近零时容易絮凝。
Zeta potential is the potential at the shear plane; larger magnitude means stronger repulsion and stability, while near zero invites flocculation.
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
#ζ电位 #胶体 #稳定
胶体有哪几类、丁达尔效应是什么？
What are the colloid types and the Tyndall effect?
按分散相与介质分溶胶、凝胶、泡沫、乳浊液等；胶体粒子散射光，形成可见的光路（丁达尔效应）。
By dispersed phase and medium they include sols, gels, foams and emulsions; colloid particles scatter light into a visible beam (Tyndall effect).
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
#胶体 #丁达尔 #分类
为什么点卤水或石膏能让豆浆变成豆腐？
Why does adding bittern or gypsum turn soymilk into tofu?
豆浆是大豆蛋白胶体，加入盐卤（氯化镁）或石膏（硫酸钙）等电解质，中和蛋白表面电荷使其聚沉凝固，形成豆腐。
Soymilk is a protein colloid; electrolytes like magnesium chloride (bittern) or calcium sulfate (gypsum) neutralize surface charges, causing proteins to coagulate into tofu.
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）
#豆腐 #胶体 #凝固
为什么玉米淀粉加水既像固体又像液体？
Why does cornstarch with water act like both solid and liquid?
这是非牛顿流体（剪切增稠）：慢慢伸手能插进去，快速猛击却被锁住像固体，因为颗粒在冲击下相互顶住。
It's a shear-thickening non-Newtonian fluid: slow motion lets you sink in, but a fast impact jams the particles into a solid-like response.
难度 入门 · 适合 小学高段(9-12)
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）
#非牛顿流体 #剪切增稠 #玉米淀粉