Acids – Quick Survey of General Features 1.Aqueous solutions of acids have a sour taste. 2.Acids change the color of acid-base indicators. CHEMISTRY CHAPTER 14. ACIDS AND BASES SECTION 1. PROPERTIES OF ACIDS AND BASES

3.Some acids react with active metals and release hydrogen gas, H 2. 4.Acids react with bases to produce salts and water. 5.Acids conduct electric current.

Acid Nomenclature A binary acid is an acid that contains only two different elements: hydrogen and one of the more electronegative elements. HF, HCl, HBr, and HI

The name of a binary acid begins with the prefix hydro-. The root of the name of the second element follows this prefix. The name then ends with the suffix -ic.

An oxyacid is an acid that is a compound of hydrogen, oxygen, and a third element, usually a nonmetal. ex: HNO 3, H 2 SO 4

Some Common Industrial Acids Sulfuric Acid Sulfuric acid is the most commonly produced industrial chemical in the world. Nitric Acid Phosphoric Acid

Hydrochloric Acid Concentrated solutions of hydrochloric acid are commonly referred to as muriatic acid. Acetic Acid Pure acetic acid is a clear, colorless, and pungent-smelling liquid known as glacial acetic acid.

Bases - General Features 1.Bitter taste. 2.Change the color of acid-base indicators. 3.Dilute solutions of bases feel slippery. 4.React with acids to produce salts and water. 5.Conduct electric current.

Definitions of Acids and Bases The book discusses three definitions: Arrhenius acids and bases Brønsted-Lowry acids and bases Lewis acids and bases (we will not discuss ) CHEMISTRY CHAPTER 14. ACIDS AND BASES SECTION 1. PROPERTIES OF ACIDS AND BASES

Arrhenius Acids and Bases These are the classical definitions that we used earlier: 1. An Arrhenius acid is a chemical compound that increases the concentration of hydrogen ions, H +, in aqueous solution. The H + actually combines with H 2 O to form H 3 O + (hydronium ion).

In a solution of hydrogen chloride in water to form hydrochloric acid the following reaction occurs: HCl(g) + H 2 O(l) → H 3 O + (aq) + Cl - (aq)

2. An Arrhenius base is a substance that increases the concentration of hydroxide ions, OH −, in aqueous solution. a.Ionic hydroxides ex.: KOH → K + + OH - b.Compounds that react with water to generate OH - ex.: NH 3 + H 2 O → NH OH -

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Aqueous Solutions of Acids Arrhenius acids are molecular compounds with ionizable hydrogen atoms. Their water solutions are known as aqueous acids. All aqueous acids are electrolytes.

Common Aqueous Acids

Strength of Bases The strength of a base depends on the extent to which the base dissociates. Strong bases are strong electrolytes

Brønsted-Lowry Acids and Bases A Brønsted-Lowry acid is a molecule or ion that is a proton donor. Ex.: HCl when it reacts with H 2 O or NH 3 : HCl + H 2 O → Cl - + H 3 O + HCl + NH 3 → Cl - + NH 4 + Note that HCl is a Brønsted-Lowry acid in both cases, even though H 3 O + is not formed in the second reaction. SECTION 2. ACID-BASE THEORIES

Water can act as a Brønsted- Lowry acid: A Brønsted-Lowry base is a molecule or ion that is a proton acceptor. What are the Brønsted-Lowry bases in the examples above?

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Svante Arrhenius Johannes Br  nsted Thomas Martin Lowry wikipedia

Conjugate Acids and Bases When a Brønsted-Lowry acid gives up a proton, the species that remains is called the conjugate base of the acid, because it can accept a proton when the reaction goes in reverse. Similarly, the species that forms when a base gains a proton is the conjugate acid.

Ex.: HF + H 2 O → F - + H 3 O + acid base conj. conj. base acid of HF of H 2 O reverse: F - + H 3 O + → HF + H 2 O

In general, a reversible acid-base reaction consists of two –pairs of conjugate acids and bases: HF + H 2 O ↔ F - + H 3 O + acid 1 base 2 base 1 acid 2

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Neutralization Reactions In aqueous solutions, neutralization is the reaction of hydronium ions from an acid and hydroxide ions from a base to form water molecules. The other product is a salt formed from the cation of the base plus the anion from the acid.

Ex. 1: HCl + NaOH + H 2 O → H 3 O + + Cl - + Na + + OH - H 3 O + + Cl - + Na + + OH - → 2H 2 O + NaCl net: HCl + NaOH → H 2 O + NaCl Ex. 2: 2HBr + Ba(OH) 2 → BaBr 2 + 2H 2 O

Neutralization Reactions