CHEM321 CH18

crystal1902's version from 2016-11-28 00:08


Question Answer
colloidal particles有正的还是负的表面,particle本身有什么样的surface area,表面的正负会影响什么 for cations;为什么要学soil里的colloids:因为什么样的surface area 会影响什么reactivity,什么会影响什么和什么的transportcolloidal particles有负的表面,particles本身有很大的surface area,表面的正负会影响electrostatic attraction for cations;因为large surface area会影响surface mediated chemistry surface reactivity,charge characteristics会影响营养和有毒pollutants的transport
caly的表面是负的 relatively 什么 in magnitude,这种情况叫什么;humic materials有什么样的charged surface,所以pH是什么样的clay的表面是负的,relatively constant in magnitude,这样的情况叫montmorillonite; humic materials有various charged surfaces,他的pH是dependent的
point of zero charge的缩写有哪两个;pH指的是正负charge on a 什么正好怎么样;它是每个materal unique的property,它决定了position of 什么和什么 on the surface;determination of pH0可以通过measure 什么of a colloid depending on 什么pH (after什么)in什么和什么of various conc of 什么;ideally plot会给一个point where all curves 怎么样;ambient solution的pH小于colloid pH0的时候,surface是什么样的,什么positive surface charge,什么adsorbed;amibent 溶液的pH大于pH0, surface是什么样的,什么for cation;pH0的值越怎么样越好,也容易有什么样的表面chargepoint of zero charge的缩写是pH0或者pzc;pH at which surface positive and negative charges on a colloid are just balanced;它是每个unique property of each material,它决定了position of protonation deprotonation on the surface;determination of pH0 可以通过measure surface charge of a colloid depending on solution pH (after equalibrium)in absence and presence of various conc of a non reactive electrolyte;ideally plot会给一个point where curces interact;当amibent solution的pH小于colloid pH0的时候,surface 是protonated,net positive surface charge,anion adsorbed;amibent 溶液的pH大于pH0, surface是negative,electrostatic affinity for cations;pH0的值越low越好,因为表面更容易有negative charge
colloid是什么between什么和什么,particles不会什么,colloid有什么样的surface area,surface properties of colloid materials unique 并且depend on 什么of colloid,对环境为什么那么重要 因为colloid surface可以adsorb什么和什么from solution;colloid 很重要的三个原因是由很什么的surface area,有很多什么chemistry,什么immnobilization 和transport of 什么和什么colloid是intermediate between particulate suspensions 和solutions;particles不会settle;colloid有enormous specific surface area;surface rpoperties of colloid materials unique 并且depend on chemical nature of the colloid;对环境很重要因为colloid surface可以adsorb molecules/ions from solution;colloid很重要的三个原因是由很high 的surface area,lots of surface mediated chemistry,cation immonilization 和transport of营养和污染物
surface adsorption colloids的两种,第一种是ion exchange associated with什么,因为很多environmental colloids有负的表面charge,什么of cation is essentially an 什么process;第二种是什么of species on surface by什么,specific binding 包括 formation of 什么between什么+什么on colloid:例子surface adsorption colloids的两种,第一种是ion exchange associated with electrostatic adsorption,因为很多environmenta lcolloids有负的表面charge,electrostatic attraction of cations is essentially an ion exchange process;第二种是retention of species on surfaces by specific adsorption,specific binding包括formation of covalent bonds between solution species+surface atoms on colloid:比如adsorption of fatty acids by a hydrated iron oxide
eletrical double layer stabilizes什么 colloid:什么 of a colloid often described in terms of 什么,thickness of this layer= 什么at which potential decreases to 什么;colloidal system 比如什么或什么with 什么particles是stable的因为什么particles 什么each other,造成什么suspension of colloidelectrical double layer stablizes suspended colloid;charge properties of a colloid 通常形容为electrical double layer;thickness of this layer= distance at which potential decreases to 1/e;colloidal system 比如河或者湖 with suspended clay particles is stable 因为small charged particles repel each other,造成long lasting suspension of colloid
thickness of double layer depends on 什么; 什么of electrolyte provide a source of 什么 that accumulate around the surface,这样会什么thickness of double layer,potential falls more rapidly to 什么;当河汇流到海里的时候,sedimentation经常可以看到因为什么of river colloid;higher concentration of electrolyte=high什么,造成什么of colloid和什么thickness of double layer depends on ionic strength;higher concentration of electrolytes 提供了一个source of counter ions that accumulate around the surface,这样会decreases the thickness of double layer,potential falls more rapidly to zero;当河汇流到海的时候,会看到sedimentation 因为destablization of river colloids;high concentration of electrolyte=high ionic strength,造成destabilization of colloids 和settling out of solution