Ammonia Water NH4OH

Ammonia solution, relative density less than 0.880 at 15 °C in water, with mote than 35% but not more than 50% ammonia [2073] 

Gaseous ammonia is highly soluble in water, up to 900 g-l at 20 °C, but commonly, only less concentrated solutions, up to 30%, are used. These solutions (ammonia water) are a base that is less strong than sodium or potassium hydroxide. 

An increase in temperature has no influence on the resistance of aluminium in ammonia water. In fact, two processes are competing, attack and formation of the oxide layer, and the rate of both processes increases with temperature. These two antagonistic effects have the result that aluminium resists well, if not better, in hot ammonia water than in ammonia water at room temperature. 

Aluminium is very widely used in equipment for the transportation and the storage of ammonia water, and in production plants for nitric acid. As in gaseous ammonia, the presence of carbon dioxide CO2, sulphur dioxide SO2, hydrogen sulphide H2S, ammonium carbonate NH4CO3 and ammonium sulphide S(NH4)2 in ammonia does not alter the corrosion resistance of aluminium. On the other hand, the presence of chlorides (and of salts of certain heavy metals such as copper) has a noxious effect. 

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Nitrogen and ammonia. Nitrogen reacts much more slowly with titanium than oxygen. However, above 800°C, excessive diffusion of the nitride may cause metal embrittlement. Titanium is not corroded by liquid anhydrous ammonia at ambient temperatures. Moist or dry ammonia gas or ammonia water (NH4OH) solutions will not corrode titanium to their boiling-point and above. 

Compounds of Nitrogen. Ammonia, NHg, is an easily condensable gas (b.p. —33.35 C m.p. —77.7 C), readily soluble in water to produce an alkaline solution. The gas is colorless and has a pungent odor, often detected around st bles and manure piles, vhere ammonia is produced by decomposition of organic matter. The solution of ammonia in water is called ammonium hydroxide solution (or sometimes ammonia water or aqua ammonia). Ammonium hydroxide has the formula NH4OH. It is a ba e, which forms salts with the common acids. 

H2O serves as a base in 17-3) and as an acid in 17-4). Note that the bare of 17-1) becomes the hydrated proton or hydronium ion, HsO, of 17-3). In the formulation of equilibrium constants, [H ] and [H30 ] are always equivalent to each other the two forms are used interchangeably in most contexts and will be so used in all ionic equilibrium problems in this book. Although the proton is indeed hydrated in aqueous solutions, the notation H is often used instead of H30 because the reader understands the fact of hydration, because he need not worry about specifying the exact extent of hydration (which exceeds one H2O per proton), and because the specific use of the hydrated formula for the proton might obscure the important fact that all ions in water are extensively hydrated. Note also that the denominator in the Ka expression in 17-3) is identical with that in 17-1) since applications of these equilibria are intended for dilute solutions, H2O is always taken to be in its standard state and therefore need not be represented by a term in the expression. Equation 17-4) avoids describing aqueous ammonia as NH4OH, a species that probably does not exist at ambient temperatures. 

Synonyms Ammonia aqua Ammonia aqueous Ammonia soiution Ammonia soiu-tion, strong Ammonia water Aqua ammonia Aqua ammonium Aqueous ammonia Spirit of Hartshorn Strong ammonia soiution Classification inorganic base Empirical HjNO Formula NH4OH... 

Balabanov et al. [499] investigated the efficiency of different solutions for the washing of niobium hydroxide. The effectiveness of water and solutions of ammonia, NH4OH, ammonium acetate, CH3COONH4, and ammonium carbonate, (NH4)2C03, were tested. It was shown that ammonium acetate interacts with solid ammonium oxyfluoroniobates yielding niobium oxide even at temperatures as low as 125°C. The interaction that takes place between the solid components can be presented as follows (144) ... 

Sodium hydroxide (NaOH) (caustic soda) Potassium hydroxide (KOH) (caustic potash) Calcium hydroxide (Ca(OH)2) (slaked lime) Ammonium hydroxide (NH4OH) (aqueous ammonia solution) White deliquescent solid. Sticks, flakes, pellets. Dissolution in water is highly exothermic. Strongly basic. Severe hazard to skin tissue White deliquescent solid. Sticks, flakes, pellets. Dissolution In water is highly exothermic. Strongly basic. Severe hazard to skin tissue White powder soluble in water yielding lime water. Alkaline Weakly alkaline. Emits ammonia gas. Severe eye irritant... 

Although it is often convenient to use the formula NH4OH, it does not represent a stable molecule. Ammonia is extremely soluble in water, but it ionizes only slightly (K5 = 1.8 X 10 s),... 

To abstract a proton is to remove only the proton. The substantial extent of dissociation in Equation (6.11) helps explain why aqueous ammonia is more properly called ammonium hydroxide , NH4OH. We generate the solvated hydroxide ion OH (aq) by abstracting a proton from water. The OH (aq) ion in Equation (6.11) is chemically and physically identical to the solvated hydroxide ion generated by dissolving NaOH or KOH in water. 

Nitrite reductase (NAD(P)H) [EC 1.6.6.4] catalyzes the reaction of three NAD(P)H with nitrite to yield three NAD(P)+, NH4OH, and water. Cofactors for this enzyme include FAD, non-heme iron, and siroheme. (2) Nitrite reductase (cytochrome) [EC 1.7.2.1] is a copper-depen-dent system that catalyzes the reaction of nitric oxide with two ferricytochrome c and water to produce nitrite and two ferrocytochrome c. (3) Ferredoxin-nitrite reductase [EC 1.7.7.1], a heme- and iron-dependent enzyme, catalyzes the reaction of ammonia with three oxidized ferredoxin to produce nitrite and three reduced ferredoxin. (4) Nitrite reductase [EC 1.7.99.3] is a copper- and FAD-dependent enzyme that catalyzes the reaction of two nitric oxide with an acceptor substrate and two water to produce two nitrite and the reduced acceptor. 

Ammonia reacts with water producing NH4OH. The reaction is reversible NH4OH dissociates into NH4+ and OH- ions in solution ... 

An identification test has been established by the AO AC, 16 edition [14]. The solution is made alkaline with few drops of NH4OH, excess ammonia is expelled, and the residue dissolved in few mL of hot water. The solution may be filtered if necessary. At that point a few drops of aqueous 0.5 % FeCl3 solution is added, and a salmon color precipitate will form. 

When a salt is exposed to either water or ammonia (as vapor or as liquid) or to a mixture of the two, the reaction that takes place may be due to any of the following H20, NH3, the ions OH- or NH2-, or the ions of NH4OH. These possibilities lead to the following types of reactions ... 

When a weak base is dissolved in water, a few of the molecules accept protons from water, leaving OH ions in the solution to make it slightly basic. For many years it was said that such solutions contain the hydrated form of the base (instead of the base itself), and that the hydrated base then subsequently dissociates to a slight degree. For ammonia, it was said that NH3 first reacts with water to form NH4OH, which then dissociates slightly as a weak base. Because most of the dissolved base probably does not exist in the hydrated form in solution, it is now more acceptable to write the chemical equilibrium equation as... 

All of the above radicals are associated with a corresponding radical or element in a compound. While a radical frequently and rather generally enters into chemical reaction as a unit, it is not implied [hat this is always so, the stability in each case is characteristic of each radical and each reaction in which it is involved. Thus, ammonium hydroxide NH4OH yields ammonia gas NHr and water I liO at room temperature, ammonium nitrate NH4NO3 is decomposed, upon heating, with the accompanying disruption of both the ammonium and nitrate radicals 10 yield nitrous oxide NjO gas and water HiO... 

When ammonia is dissolved in water the deviation from Henry s law has been attributed to a chemical reaction between water and ammonia, forming ammonium hydroxide NH3+H2O NH4OH this inference is supported by the great difference, 3-4 Cals., between the heat of soln., 8-4 Cals., and the heat of condensation, 5-0 Cals. 

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