Ammonium, NH

Other preparative methods include direct synthesis from the elements, reaction between gaseous hydrogen fluoride and titanium tetrachloride, and decomposition of barium hexafluorotitanate [31252-69-6] BaTiF, or ammonium, (NH 2TiFg. 

Although ions are often individual charged atoms, there cire many examples of polyatomic ions, which are charged particles made up of more than one atom. Common polyatomic ions include ammonium, NH +, and sulfate, SO . 

Dihydrogen phosphate (H PO,-) Hydrogen phosphate (HPO/i Phosphite (POj ) Ammonium (NH +)... 

Ammonium tetrafluoroborate (7 ). Both the ammonium (NH ) and tetrafiuoroborate (BF4) ions are isoelectronic with the methane molecule and we might therefore reasonably expect them to have similar structures. Indeed, all four bonds are equivalent, and since the electrons avoid each other as much as possible, the most stable arrangement is a tetrahedron (Fig. 6.1g). 

The only common inorganic polyatomic cation is ammonium NH/. 

Table 8.2 Summary of published rates of ammonium (NH +) regeneration and dissolved organic nitrogen (DON) release from Nj fixers in the field in the light. The standard deviations were calculated using propogation of error. 

Table 8.8 Rates of ammonium (NH ) regeneration in the water column measured using N-isotope dilution C N ID) using distillation (Distill), solid phase extration (SPE), solvent extraction (SE). or diffusion (Diff)... 

Uranium solubility is increased even more in the nitrate microcosms, and one possible explanation is the conversion of acetate to CO2, coupled with nitrate reduction, which would give higher dissolved carbonate concentrations in the nitrate microcosms. However, PHREEQE modelling showed that the higher CO concentration would not greatly affect uranium speciation in solution and is therefore unlikely to account for the enhanced solubility. Alternatively, as nitrate is reduced to ammonium (NH/), which promotes cation exchange, this could lead to displacement of U02 from surface complexes, which are the predominant uranyl species on mineral surfaces. " ... 

Dinitro-3-dimethylaminophenol yel crysts, mp 191—95° forms expl salts Ammonium, NH CaHaNgOg, gold-yel pltlts, mp 195° Barium, Ba(CaHsN305)2 + l H20, ppt of orn-red crysts Potassium, KCaHaNgOs, orn-red ndls and Silver, AgCaHaNgOg,... 

Whal Is the pH ol an ammonium acetate solution The pKj, ol the ammonium (NH, ) cation Is 9.3. Always bear in mmd that the pK refers to the ability ol the proton donor lorm to release the proton Into water to lorm HjC noe this is the salt ol a weak acid (NH4 ) and the conjugate base ol a weak acid (acetate anion), the lollowing equation la used. Note that molar concentration is not a variable in this calculation... 

It is very unlikely tltat an MCAT question Nearly all ionic compounds containing nitrate (NO-T), ammonium (NH/), and al-tfOiircf require that you know these kali metals (Li+, Na, K+...) are soluble. solubilities. However, knowing them will... 

Ammonium (NH " Calcium Sulfur dioxide Nitrogen oxides Hydrochloric acid Organic acids Hydrogen peroxide Ozone... 

Anaerobic organisms are able to use oxidized chemical species such as nitrate (NO ) as electron acceptors in place of molecular oxygen. Consequently, microbial reduction of nitrate to N2 (a process termed denitrification ) occurs in the early stages of soil reduction, as does Mn oxide reduction to Mn. Reduced species such as nitrite (NO ) and Mn then appear in solution. As more extreme reducing conditions develop, ammonium (NH ) accumulates from nitrogen reduction reactions, and iron solubility increases in the form of Fe. The elevated iron and manganese solubility is ultimately limited by precipitation of the rather insoluble carbonates of Fe (siderite) and Mn (rhodochrosite) if the soil pH is not too low ... 

Barium titanate BaTi03 is usually considered as the prototype of compounds having a purely displacive ferroelectric phase transition, which exhibits a soft mode describable by an anharmonic phonon. The nonferro-electric compound NH4C1 is another example of compound with pure order-disorder phase transition, with two phases that differ from the ordering of the ammonium (NH/) cation in the unit cell. 

Ammonia is the primary basic gas in the atmosphere and, after N2 and N20, is the most abundant nitrogen-containing compound in the atmosphere. The significant sources of NH3 are animal waste, ammonification of humus followed by emission from soils, losses of NH3-based fertilizers from soils, and industrial emissions (Table 2.8). The ammonium (NH ) ion is an important component of the continental tropospheric aerosol. Because NH3 is readily absorbed by surfaces such as water and soil, its residence time in the lower atmosphere is estimated to be quite short, about 10 days. Wet and dry deposition of NH3 are the main atmospheric removal mechanisms for NH3. In fact, deposition of atmospheric NH3 and NH4" may represent an important nutrient to the biosphere in some areas. Atmospheric concentrations of NH3 are quite variable, depending on proximity to a source-rich region. NH3 mixing ratios over continents range typically between 0.1 and lOppb. 

The solution of ammonia in HaO constitutes a strongly alkaline liquid, known as aqua ammonise, which is ijossessed of strongly basic properties. It is neutralized by acids with the formation of crystalline salts, which are also formed, without liberation of hydrogen, by direct union of gaseous NHa, with acid vapors. The ammoniacal salts and the alkaline base in aqua ammonise are compounds of a radical, ammonium, NH, which forms compounds corresponding to those of potassium or sodium. The compound... 

The ammonium theory.—Although the radical ammonium, NH, has probably never been isolated, its existence in the ammoniacal comisounds is almost universally admitted. The ammonium hypothesis is based chiefly upon the following facts (1) the close resemblance of the ainmoniacaJ salts to those of K and Na (2) when ammonia gas and an acid gas come together, they unite, without liberation of hydrogen to form an ammoni-acal salt (3) the diatomic aiihydrids unite directly with dry ammonia with formation of the ammonium salt of an amido acid ... 

---