Primary, secondary, and tertiary ammonium salts serve the same function but are less lipophilic. These cations, such as the tetra- n-butylammonium cation, are sometimes used to replace sodium or potassium ions to increase the solubility of the associated anion in organic solvents. Quaternary ammonium cations have four organic groups attached to the nitrogen atom, they lack a hydrogen atom bonded to the nitrogen atom. Except the quaternary ammonium cations, the organic ammonium cations are weak acids.Īn example of a reaction forming an ammonium ion is that between dimethylamine, (CH 3) 2NH, and an acid to give the dimethylammonium cation, +: Depending on the number of organic groups, the ammonium cation is called a primary, secondary, tertiary, or quaternary. The hydrogen atoms in the ammonium ion can be substituted with an alkyl group or some other organic group to form a substituted ammonium ion ( IUPAC nomenclature: aminium ion). KC 4H 5O 6(aq) + +(aq) → C 4H 5O 6(s) + K +(aq) Structure and bonding Na 3(aq) + 3 +(aq) → 3(s) + 3 Na +(aq)Īmmonium ion gives a white precipitate of ammonium bitartrate when added to potassium bitartrate. H 2(aq) + +(aq) → 2(s) + 2 H +Īmmonium ion when added to sodium cobaltinitrite gives a yellow precipitate of ammonium cobaltinitrite. To further confirm ammonia, it passed through a glass rod dipped in an HCl solution ( hydrochloric acid), creating white dense fumes of ammonium chloride.Īmmonia, when passed through CuSO 4 ( copper(II) sulfate) solution, changes its color from blue to deep blue, forming Schweizer's reagent.ĬuSO 4(aq) + 4 NH 3(aq) + 4 H 2O → (OH) 2(aq) + H 2SO 4(aq)Īmmonia or ammonium ion when added to Nessler's reagent gives a brown color precipitate known as the iodide of Million's base in basic medium.Īmmonium ion when added to chloroplatinic acid gives a yellow precipitate of ammonium hexachloroplatinate(IV). To find whether the ammonium ion is present in the salt, first, the salt is heated in presence of alkali hydroxide releasing a gas with a characteristic smell, which is ammonia. This amalgam eventually decomposes to release ammonia and hydrogen. Such species are prepared by the addition of sodium amalgam to a solution of ammonium chloride. In an unusual process, ammonium ions form an amalgam. The ammonium salts of nitrate and especially perchlorate are highly explosive, in these cases, ammonium is the reducing agent. An exception is ammonium hexachloroplatinate, the formation of which was once used as a test for ammonium. Most simple ammonium salts are very soluble in water. Salts and characteristic reactions Formation of ammoniumĪmmonium cation is found in a variety of salts such as ammonium carbonate, ammonium chloride, and ammonium nitrate. If the pH is high (the concentration of hydrogen ions is low and hydroxide ions is high), the equilibrium shifts to the left: the hydroxide ion abstracts a proton from the ammonium ion, generating ammonia.įormation of ammonium compounds can also occur in the vapor phase for example, when ammonia vapor comes in contact with hydrogen chloride vapor, a white cloud of ammonium chloride forms, which eventually settles out as a solid in a thin white layer on surfaces. If the pH is low, the equilibrium shifts to the right: more ammonia molecules are converted into ammonium ions. The degree to which ammonia forms the ammonium ion depends on the pH of the solution. When ammonia is dissolved in water, a tiny amount of it converts to ammonium ions: Thus, the treatment of concentrated solutions of ammonium salts with a strong base gives ammonia. The ammonium ion is mildly acidic, reacting with Brønsted bases to return to the uncharged ammonia molecule: The ammonium ion is generated when ammonia, a weak base, reacts with Brønsted acids ( proton donors): Ammonium is also a general name for positively charged (protonated) substituted amines and quaternary ammonium cations ( +), where one or more hydrogen atoms are replaced by organic or other groups (indicated by R).Īcid–base properties Fumes from hydrochloric acid and ammonia forming a white cloud of ammonium chloride It is formed by the protonation of ammonia ( NH 3). The ammonium cation is a positively charged polyatomic ion with the chemical formula NH + 4 or +.
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