Ammonium chloride, oxidation state elements

Most ionic halides dissolve in water to give hydrated metal ions and halide ions. However, the lanthanide and actinide elements in the +3 and +4 oxidation states form fluorides insoluble in water. Fluorides of Li, Ca, Sr, and Ba also are sparingly soluble, the lithium compound being precipitated by ammonium fluoride. Lead gives a sparingly soluble salt PbCIF, which can be used for gravimetric determination of F . The chlorides, bromides, and iodides of Ag1, Cu1, Hg1, and Pbn are also quite insoluble. The solubility through a series of mainly ionic halides of a... 

One sees that the oxidation state equals the charge of the ion. The cations are normally named just by adding ion after the name of the element (Mg = magnesium ion) whereas the suffix -id replaces the suffix of the element for anions (Cf = chloride). For composite ions, a shared (total) oxidation number is used. This shared oxidation state is the sum of all the oxidation states for the different ions in the composite ion. Uncharged atoms have the oxidation number of zero. The ammonium ion and hydroxide are both examples of composite ions ... 

Adding ammonium chloride decreases the solubility of aluminum hydroxide and prevents the precipitation of magnesium hydroxide. Scott 13) states that the precipitation of nickel, cobalt, manganese, and zinc sulfides may be incomplete because of the formation of polysulfides in the presence of air or other oxidizing agents. A small amount of ammonium sulfite is therefore added to promote their precipitation. In spite of this precaution, cobalt, nickel, and manganese were never quantitatively recovered and the procedure is not considered entirely satisfactory for these elements. 

A) Oxidation states of transition elements. In four large test tubes place about 20 ml of dilute solutions of titanic chloride, ammonium metavanadate, potassium dichromate, and ammonium molybdate. Add to each about 10 ml of concentrated hydrochloric acid and several grams of granulated or mossy zinc. Set under the draft. Note all the color changes and interpret them by means of ionic equations. 

An ionic compound is named with the cation name first, followed by the name of the anion the word ion is omitted in each case. The oxidation number of the cation is given if more than one charge is possible. However, if the cation comes from an element that exists in only one charge state (as listed in Fig. C.6), then the oxidation number is omitted. Typical names include potassium chloride (KC1), a compound containing K+ and Cl" ions and ammonium nitrate (NH4NOs), which contains NH4+ and NO3" ions. The cobalt chloride that contains Co2+ ions (CoCl,) is called cobalt(II) chloride C0CI3 contains Co3+ ions and is called cobalt(III) chloride. 

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