Lewis acids & bases

发布网友发布时间：2023-06-18 10:38

共1个回答

热心网友时间：2023-06-21 22:25

更新1:

中文的化学词汇不太看的懂= =" 请用英文回答...

更新2:

Thank you very much for the trlation!!! However
I can't hardly understand the affect of anions size on their stability. Actually what do you mean by a more even electron distribution? Also
what is the electron density? I think that should be sth aboutl those electron orbitals
right?

更新3:

Another question is that for the ammonia case
what makes ammonia a base? Is that the energy released by the formation of the new N-H bond is greater than that to destroy a O-H bond in water? I also wonder whether the reaction is exothermic or endothermic as water is quite a weak Lewis base.

更新4:

Umm....silly grammar mistake I can't hardly understand->I can hardly understand

更新5:

但为什么反应一会进行?因为N的en也不弱?但相比下O的较强
所以解离常数很低?

1)路易斯酸是接收孤电子对路易斯碱是提供孤电子对考虑酸平衡 HA+H2O-->H3O+ + A- HA是酸 F- 体积比Cl-细
Cl-能更有效分散负电荷(较稳定)
使平衡位置在右方
酸性较高 Cl-较F-稳定代表HCl较HF不稳定 (平衡相对性) 所以可理解HCl较易接收接收孤电子
较强路易斯酸所以I岩同样也可理解F-较易提供孤电子对
所以F-是较强路易斯碱 F-是较强路易斯碱
F2也是较强路易斯碱所以2都岩 F2是较强路易斯碱
代表其离子也是较强路易斯碱
代表HF是较弱路易斯酸所以statement 2 is the correct explanation for that hydrofluoric acid is a weak acid in water2)化学反应定义是有新物质生成 I.Ammonia dissolve in water 有 NH3溶水 NH3(g)-->NH3(aq) NH3和水发生化学反应 NH3+H2O-->NH4+ + OH- 生成新物质NH4+ OH-II.Hydrochloric acid dissolve in water 有 HCl溶水 HCl(g)-->HCl(aq) HCl和水发生化学反应 HCl+H2O-->H3O+ + Cl- 生成新物质 H3O+ Cl-III. Sodium hydroxide dissolve in water 没有 NaOH溶水 NaOH(s)-->Na+(aq)+OH-(aq) 它和水没有反应3)不会
h+ 会形成h3o+
是因为h+体积太小
和水结合的水合能很高结合形式是h2o的孤电子对和h+的低能量空轨态形成配位共价键 oh-不会形成
因为体积大
h没有能量空轨态
而水的h也没有能量空轨态 2012-05-14 18:28:28 补充：体积大，轨态(orbital)也越大，自然容纳两粒孤电子的空间较大，电子密度(charge density)也越小，电子密度可理解成电子在轨态的密度，越高，孤电子越容易提供，越低，电子越难提供事实上，键能（bond energy)同酸碱离解度，没有直接关系，因为键能主要是影响活化能(Ea)
而主要影响因素，是离子的稳定性，考虑以下平衡 2012-05-14 18:28:32 补充： NH3+H2O-->NH4+ + OH- NH3+H2O--->NH2- + H3O+ OH-比NH2-稳定得多，所以反应二基本下会进行，可假设NH3只作碱（BASE)就可 O en > N en
抓住孤电子能力大，所以较稳定这不用体积解释，是因为同周期体积变化小，只考虑En就可而同族就用体积解释，因为由上至上，体积变化很大，这影响远远大于En 估计NH3+H2O-->NH4+ + OH- 是吸热反应，因为离解常数低 Kb=1.8x10^-5 2012-05-14 18:33:13 补充： OH-比NH2-稳定得多，所以反应二基本不会进行，可假设NH3只作碱（BASE)就可 O en > N en
抓住孤电子能力大，所以较稳定 2012-05-14 18:33:52 补充：这不用体积解释，是因为同周期体积变化小，只考虑En就可而同族就用体积解释，因为由上至下，体积变化很大，这影响远远大于En 2012-05-14 23:27:39 补充：离解常数是由能量决定的在很多平衡反应中，反应物也有足够能量克服Ea，进行正向反应所以在这情况下比较离子稳定性，就可而不用考虑反应物的en，这是动力学（速率）的因素
参考: my
The following is ONLY the TRANSLATED piece of wer from 小云 I’m not sure about its correctness! Things in [ ] are my opinion/supplement Here you are: 1) Lewis acid accepts lone pair of electrons Lewis base donates lone pair of electrons 2012-05-12 17:55:59 补充： Concerning the dynamic equilibrium of acid HA HA + H2O <----> H3O+ + A- As F- ion is *** aller than Cl- in size
Cl- can have a more even distribution of negative charge [which is from electrons] 2012-05-12 17:56:23 补充： This make Cl- more stable [than F-]
So
the equilibrium position lies [more] on the right [for “HCl + H2O <----> H3O+ + Cl-” than “HF + H2O <----> H3O+ + F-”] 2012-05-12 17:56:35 补充： [Thus
there will be more H3O+ in the equilibrium of hydrochloric acid than that of hydrofluoric acid] [Such that hydrochloric acid is] more acidic [than hydrofluoric acid] 2012-05-12 17:57:09 补充： Cl- is more stable than F- me that HCl is less stable than HF [“平衡相对性”
I don’t know what is it = =] Which can be understood as HCl accepts electrons better and thus is a stronger Lewis acid So
statement I is correct 2012-05-12 17:58:06 补充： {In the same sense
F- donates lone pair of electrons [easier than Cl-] So
F- is a stronger Lewis base [than Cl-] F- is a strong Lewis base And F2 is also a strong Lewis base So
2 is correct 2012-05-12 17:58:16 补充： F2 is also a strong Lewis base me that its ions are also strong Lewis base
Thus
it me that HF is a weak Lewis acid So
statement 2 is the correct explanation for that hydrofluoric acid is a weak acid in water.} [Things in{} are quite confusing
not really know what they me] 2012-05-12 17:58:27 补充： 2) Definition of chemical reaction is that there are new substance(s) formed I. Ammonia dissolve in water New substance formed NH3 dissolve in water: NH3(g)-->NH3(aq) NH3 then react with water: NH3+H2O-->NH4+ + OH- New substances formed : NH4+ and OH- 2012-05-12 17:58:56 补充： II. Hydrochloric acid dissolve in water New substance formed HCl dissolve in water: HCl(g)-->HCl(aq) HCl then react with water: HCl+H2O-->H3O+ + Cl- New substances formed : H3O+ and Cl- 2012-05-12 17:59:02 补充： III. Sodium hydroxide dissolve in water No new substances formed NaOH dissolve in water: NaOH(s)-->Na+(aq)+OH-(aq) It has no reaction with water 2012-05-12 17:59:23 补充： 3) No [OH- won’t form covalent bonds with water as H+ does] H+ forms H3O+ is because the size of H+ is too *** all that the hydration energy is very high The way of bining [H+ and H2O] is: 2012-05-12 17:59:36 补充： Lone pair of H2O forms dative covalent bond[=coordinate bond] with the low-energy empty orbital of H+ OH- won’t form [covalent bonds with water as H+ does] 2012-05-12 18:00:13 补充： Because it is large
[and its] H [atom] have no [low-energy] empty orbital
neither do the H atom[s] of water. [I don’t quite understand what’s it saying for Q3] That's all
hope I can help you =]