University:
Seattle Pacific University
Course:
CHM 1211 | General Chemistry I
Academic year:

2022
Views:

85

Pages:

2
Author:

Carissa Thomas

Naming Inorganic Acids Acids are important hydrogen-containing molecular compounds, whose names follow special rules. For the moment, we can define an acid as a compound that in water can produce electrically equivalent numbers of hydrogen ions and anions; e.g., HCl H+ + Cl– H2SO4 2H+ + SO42– In general, the formulas of inorganic acids have H written first, whereas hydrogen-containing inorganic compounds that are not acids do not have H written first. Acids: HCl, HCN, HNO3, H2SO4, H3PO4 Not acids: LiH, BeH2, NH3, PH3 An oxoacid is an acid containing hydrogen, oxygen, and another element. The anion produced when an oxoacid dissolves in water is an oxoanion. The names of oxoacids follow the following rules: 1. If a central atom can form two different oxoanions, the one with more oxygen atoms is named with the -ate suffix, and the one with fewer oxygen atoms is named with the ite suffix. Anion Name Anion Name NO3– nitrate ion NO2– nitrite ion SO42– sulfate ion SO32– sulfite ion 2. If the anion name ends in -ate, the corresponding acid name ends in -ic. Anion Name Acid Name NO3– nitrate ion HNO3 nitric acid SO42– sulfate ion H2SO4 sulfuric acid 3. If the anion name ends in -ite, the corresponding acid name ends in -ous. Anion Name Acid Name NO2– nitrite ion HNO2 nitrous acid SO32– sulfite ion H2SO3 sulfurous acid 4. When a central atom can form three or four oxoacids, both the anions and the oxoacids are distinguished with the prefix hypo- and per- for the species with the fewest and most oxygen atoms, respectively. Anion Name Acid Name ClO– hypochlorite ion HClO hypochlorous acid ClO2– chlorite ion HClO2 chlorous acid ClO3– chlorate ion HClO3 chloric acid ClO4– perchlorate HClO4 perchloric acid Acid anions have H atoms that they can lose as H+ in water. The names of these ions add hydrogen in front of the name of the corresponding ion that does not have H in it. If the acid anion has two or more hydrogen atoms capable to forming H+, the appropriate Greek prefix is used to indicate the number. Mono- is omitted if only one acid anion is possible. Acid Ion Name HCO3– hydrogen carbonate ion HSO4– hydrogen sulfate ion HPO42– monohydrogen phosphate ion H2PO4– dihydrogen phosphate ion Binary hydrogen compounds with nonmetals may form H+ and an anion when dissolved in water. The acidic solutions are named as if they were molecular acids, using the usual name for the compound itself, replacing hydrogen with hydro- and the suffix -ide with -ic . The word acid is then added. The formula for such a compound in water is often distinguished from the compound itself by (aq), indicating water (aqueous) solution. Compound Name Acid Solution Name HCl hydrogen chloride HCl(aq) hydrochloric acid HCN hydrogen cyanide HCN(aq) hydrocyanic acid H2S hydrogen sulfide H2S(aq) hydrosulfuric acid HCN, although not a binary compound, is analogous to the binary hydrogen halides (HCl, HBr, HI), and so as an acid is named in a similar manner. The name of H2S(aq) as an acid is slightly irregular in using the full stem name of the element.