Question

pKa pKa -10: HI, among the hydrogen halides, the acidity is HI> HBr> HCI> HF -5: H2S04 and HC, and protonated carbonyl groups. HO-S-OH H-C pKa: Oxonium Ions: protonated water, protonated alcohols, and protonated ethers are strong acids. 1s pKa 5: Carboxylic acids, carbonic acid, and protonated anilines (Nitrogen with at least on benzene ring attached) are of medium strength. 1o ego pKa 10: Phenols, protonated amines (ammonium ions), and thiols are weak acids. OH R'-- pKa 15: The approximate pKa of water and alcohols pKa 35: Amines: H uncharged N with H attached

Answer 1

HCl + H2O rightharpoonoverleftharpoon H3O + pKa -5 0 Generalization: lower the pKa, easy to lose proton and hence stronger the acid. Thus when HCl is added to water it gives hydronium ions. Which are strong acid in itself. Sodium Alcoxide ion is basic in nature, in presence of hydronium ions it will abstract proton to give alcohol. Now Alcohol is a conjugate acid with pKa = 15 which is greater than that of hydronium ion. Hence reaction will favor in formation of the product. Here, hydronium ion is an acid to protonate alcohol. The acid and conjugate acid both have almost same pKa hence reaction will be in equilibrium and hence will not be as exergonic as first reaction. \r\n As hydronium ion is more acidic than that of ammonium ion and COOH the reaction proceeds in forward direction more. But the difference between pKa's of acid and conjugate acid is not that high