Acids nonmetal hydrides

Molecules in polar liquids such as water, liquid ammonia, sulfuric acid, and chloroform are held together by dipole-dipole and hydrogen bonding interactions. For molecules of comparable size, these are stronger than London forces resulting in the familiar trends in boiling points of nonmetal hydrides. For the heavier molecules, such as H2S, H,Se, PH3, and HI, dipole effects are not particularly important (the elec-... 

Binary compounds (compounds with only two elements) containing hydrogen are called hydrides. Hydrides can be basic, acidic, or neutral. On the periodic table, the basic hydrides are to the left, and the acidic hydrides are to the right. For instance, NaH is basic H,S is acidic. Following this trend, metal hydrides are either basic or neutral, while nonmetal hydrides are acidic or neutral. (Ammonia, NH3, is an exception to this rule.) The acidity of nonmetal hydrides tends to increase going down the periodic table. H20 < H2S < H,Se < H2Te... 

Many of the molecular (nonmetal) hydrides are acidic their aqueous solutions contain hydrogen ions. These include HF, HCl, HBr, HI, H2S, H2Se, and H2Te. 

The acid strength of nonmetal hydrides increases towards the right and to the bottom of the periodic table. Acid strengths of oxoacids can be predicted approximately from their formulae by Pauling s rules. Metal cations with polarizing character are acidic in water, and some form amphoteric oxides or hydroxides. 

CHLOROCHROMIC ANHYDRIDE (14977-61-8) A powerful oxidizer. Violent reaction with water, producing hydrochloric and chromic acids, and chlorine gas. Potentially violent and explosive reaction with reducing agents, acetone, alcohols, calcium sulfide, combustible materials, gaseous or liquid ammonia, ethers, nonmetal halides, fuels, nonmetal hydrides, fluorine, organic matter, organic solvents, phosphorus, phosphorus trichloride, sodium azide, elemental sulfur, sulfur monochloride, turpentine, urea. Decomposes slowly in light. 

Figure 18.11 The effect of atomic and molecular properties on nonmetal hydride acidity. As the electronegativity of the nonmetal (E) bonded to the ioniz-able proton increases left to right), the acidity increases. As the length of the E—H bond increases (fop to bottom), the bond strength decreases, so the acidity increases. (In water, HCI, HBr, and HI are equally strong.)...

The strength of an acid depends on its ability to donate a proton, which depends in turn on the strength of the bond to the acidic proton. In this section, we apply trends in atomic and bond properties to determine the trends in acid strength of nonmetal hydrides and oxoacids and discuss the acidity of hydrated metal ions. 

All oxoacids have the acidic H atom bonded to an 0 atom, so bond strength (length) is not a factor in their acidity, as it is with the nonmetal hydrides. Rather, two factors determine the acid strength of oxoacids the electronegativity of the central nonmetal (E) and the number of 0 atoms. 

Understand how electronegativity and bond length, polarity, and strength affect the acid strength of nonmetal hydrides and oxoacids, and explain why certain metal ions form acidic solutions ( 18.6) (EPs 18.68-18.75)... 

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