Naming Acids and Bases

I CAN name or write the formula for an inorganic acid or base.

Acids and Bases ACIDS and BASES are two groups of compounds that have special properties. In 1884 Svante Arrhenius defined an acid as a material that can release a hydrogen ion (H+1) when dissolved in water (aqueous solution). [releases a proton in other words].

According to Arrhenius, a base is a substance that, when dissolved in water, can release hydroxide ions (OH-1) in the solution.

The pH Scale The strength of an acid or base depends on the degree to which is dissolves in water. If the acid/base completely dissolves, it forms a STRONG acid/base. If the acid/base dissolves to a lesser extent, it forms a WEAK acid/base. The strength of an acid or base is measured on the pH Scale. The pH scale measures the concentration of H+1 ions formed when an acid or base substance dissolves in water.

The pH Scale ranges from 0 to 14. 7 is considered NEUTRAL…a substance is neither and acid or a base. PURE WATER is considered NEUTRAL and has a pH of 7. An ACID has a pH less than 7. The closer the pH is to 0, the stronger the acid is. A BASE has a pH greater than 7. The closer the pH is to 14, the stronger the base is.

We will discuss pH calculations and acids/bases in more depth later.

Properties of Acids and Bases ACIDS BASES Sour Taste (lemons) Bitter Taste (baking soda) Strong, Burning Odor Generally No Odor Caustic (damages living tissue/surfaces) Caustic Feels sticky Feels oily Reacts with metals forming H2 gas Reacts with fats/oils to form soap Has a pH less than 7 Has a pH above 7

NAMING ACIDS and BASES The name of an acid is determined based on the type of substance it is. INORGANIC ACIDS (the only ones we will talk about now) can easily be recognized from their formulas. An ACID’s formula will: Have HYDROGEN as it’s cation. Generally have an (aq) indicating it is in an aqueous solution at the end of the formula: EXAMPLE: H2SO4(aq)

There are TWO TYPES of inorganic acids. 1. BINARY ACIDS – have a binary formula consisting of hydrogen and one other element. Example HCl(aq) HBr(aq) H2S(aq) 2. COMPLEX ACIDS* – consist of hydrogen and a polyatomic anion. Example H2SO4(aq) or H3PO4(aq) *sometimes called “OXYACIDS”

NAMING BINARY ACIDS To name a BINARY ACID: 1. Use the prefix HYDRO to indicate the presence of hydrogen. 2. Name the elemental anion but change its ending to IC (may be hard to decide how). Example – chlorine becomes chloric but sulfur becomes sulfuric. 3. Add “acid” to the end of the name.

PRACTICE PROBLEMS Names these BINARY ACIDS: 1. HF(aq) Hydro - fluorine become fluoric - then add acid. Hydrofluoric Acid 2. H2S(aq) Hydro – sulfur becomes sulfuric – then add acid. Hydrosulfuric Acid

NAMING COMPLEX ACIDS To name a COMPLEX ACID: 1. Hydro is NOT USED. 2. Use the name of the non-oxygen element in the polyatomic anion as the basis of the name. 3. Change the ending of the anion based on the number of oxygen atoms it contains: Lower number of oxygen – ending changes to OUS. Higher number of oxygen – ending changes to IC. *if only one Polyatomic Ion, use the IC ending.

EXAMPLES H2SO3(aq) and H2SO4(aq) -no hydro -no hydro -base name on S -base name on S -fewer O = OUS ending -more O = IC ending -add “acid” to ending -add “acid” to ending Sulfurous Acid Sulfuric Acid

MORE PRACTICE PROBLEMS Name these BINARY ACIDS: HI(aq) HF(aq) HCl(aq) HBr(aq) Hydroiodic Acid Hydrofluoric Acid Hydrochloric Acid Hydrobromic Acid Name the COMPLEX ACIDS: H2CO3(aq) HClO3(aq) HNO2(aq) H3PO3(aq) Carbonic Acid Chloric Acid Nitrous Acid Phosphorous Acid

Naming Inorganic Bases Naming an inorganic base is simple: 1. Name the cation of the base by its name. 2. Add “hydroxide” to the ending. EXAMPLE Ca(OH)2(aq) Calcium Hydroxide

PRACTICE PROBLEMS Name these bases: Al(OH)3(aq) KOH(aq) NaOH(aq) Aluminum Hydroxide Potassium Hydroxide Sodium Hydroxide