Acids and Bases ALL flashcards 50

Properties of Acids and Bases

Acids are identified by their properties.
Some acids are useful in industry.
The properties of bases differ from those of acids.
Arrhenius acids and bases produce ions in solution.

Key Terms

Binary acid: An acid that contains only two different elements: hydrogen and one of the more electronegative elements.
Arrhenius acid: A chemical compound that increases the concentration of hydrogen ions, $H^+$ , in aqueous solution.
Strong acid: An acid that ionizes completely in aqueous solution.
Oxyacid: An acid that is a compound of hydrogen, oxygen, and a third element, usually a nonmetal.
Arrhenius base: A substance that increases the concentration of hydroxide ions, $OH^-$ , in aqueous solution.
Weak acid: An acid that releases few hydrogen ions in aqueous solution.

Properties of Acids

Aqueous solutions of acids have a sour taste. However, taste should NEVER be used as a test to evaluate any chemical substance because many acids, especially in concentrated solutions, are corrosive and can be poisons.
Acids change the color of acid-base indicators.
Some acids react with active metals and release hydrogen gas, $H_2$ .

Metals above hydrogen in the activity series undergo single-displacement reactions with certain acids.
Example: $\text{Ba}(s) + H*2SO*4(aq) \longrightarrow BaSO*4(s) + H*2(g)$

Acids react with bases to produce salts and water.

When chemically equivalent amounts of acids and bases react, the acid is neutralized.
The reaction products are water and an ionic compound called a salt.

Acids conduct electric current.

Some acids completely separate into ions in water and are strong electrolytes.
Other acids are weak electrolytes.

Acid Nomenclature

Binary Acid Nomenclature

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*.

Oxyacid Nomenclature
An oxyacid is an acid that is a compound of hydrogen, oxygen, and a third element, usually a nonmetal.
Oxyacids are one class of ternary acids, which are acids that contain three different elements.
The elements in an oxyacid formula are usually written as one or more hydrogen atoms followed by a polyatomic anion.
Examples:
- Acetic acid: $CH*3COOH, CH*3COO^−$ (acetate)
- Carbonic acid: $H*2CO*3, CO_3^{2−}$ (carbonate)
- Hypochlorous acid: $HClO, ClO^−$ (hypochlorite)
- Chlorous acid: $HClO*2, ClO*2^−$ (chlorite)
- Chloric acid: $HClO*3, ClO*3^−$ (chlorate)
- Perchloric acid: $HClO*4, ClO*4^−$ (perchlorate)
- Iodic acid: $HIO*3, IO*3^−$ (iodate)
- Nitrous acid: $HNO*2, NO*2^−$ (nitrite)
- Nitric acid: $HNO*3, NO*3^−$ (nitrate)
- Phosphorous acid: $H*3PO*3, PO_3^{3−}$ (phosphite)
- Phosphoric acid: $H*3PO*4, PO*4^{3−}$ (phosphate)
- Sulfurous acid: $H*2SO*3, SO_3^{2−}$ (sulfite)
- Sulfuric acid: $H*2SO*4, SO*4^{2−}$ (sulfate)

Industrial Acids

Sulfuric Acid
Most commonly produced industrial chemical.
Used in petroleum refining, metallurgy, and fertilizer manufacture.
Essential in the production of metals, paper, paint, dyes, detergents, and chemical raw materials.
Used in automobile batteries.
Concentrated sulfuric acid is an effective dehydrating agent.
Nitric Acid
Solutions are widely used in industry.
Stains proteins yellow.
Used in making explosives, rubber, plastics, dyes, and pharmaceuticals.
Initially colorless but becomes yellow due to decomposition to brown nitrogen dioxide gas.
Phosphoric Acid
Used for manufacturing fertilizers and animal feed.
Dilute phosphoric acid is used as a flavoring agent in beverages and as a cleaning agent for dairy equipment.
Important in the manufacture of detergents and ceramics.
Hydrochloric Acid
The stomach produces HCl to aid in digestion.
Used for “pickling” iron and steel (removing surface impurities).
Used as a general cleaning agent, in food processing, in the activation of oil wells, in the recovery of magnesium from seawater, and in the production of other chemicals.
Concentrated solutions (muriatic acid) are used to maintain acidity in swimming pools and to clean masonry.
Acetic Acid
Pure acetic acid is a clear, colorless, and pungent-smelling liquid known as glacial acetic acid (freezing point of $17^\circ C$ ).
Vinegars contain acetic acid (4% to 8% in white vinegar).
Used industrially in synthesizing chemicals for plastics manufacture.
A raw material in the production of food supplements (e.g., lysine).
Also used as a fungicide.

Properties of Bases

Aqueous solutions of bases taste bitter. Taste should NEVER be used to test if a substance is a base because many bases are caustic and cause severe burns.
Bases change the color of acid-base indicators.
Dilute aqueous solutions of bases feel slippery.
Bases react with acids to produce salts and water. Neutralization occurs.
Bases conduct electric current. They form ions in aqueous solutions and are electrolytes.

Arrhenius Acids and Bases

Arrhenius acid: A chemical compound that increases the concentration of hydrogen ions, $H^+$ , in aqueous solution.
Arrhenius base: A substance that increases the concentration of hydroxide ions, $OH^-$ , in aqueous solution.
Acids are molecular compounds with ionizable hydrogen atoms. Their water solutions are known as aqueous acids.
All aqueous acids are electrolytes.
Hydrogen ion in aqueous solution is best represented as $H_3O^+$ , the hydronium ion.
Example:
- $\text{HNO}\%3(l) + H*2O(l) \longrightarrow H*3O^+(aq) + NO*3^-(aq)$

Strength of Acids

Strong acid: An acid that ionizes completely in aqueous solution (strong electrolyte).
- Examples: Perchloric acid ( $HClO*4$ ), hydrochloric acid (HCl), and nitric acid ( $HNO*3$ ).
Acid strength increases with increasing polarity and decreasing bond energy.
Weak acid: An acid that releases few hydrogen ions in aqueous solution.
Aqueous solution contains hydronium ions, anions, and dissolved acid molecules.
Example: Hydrocyanic acid (HCN).
- $\text{HCN}(aq) + H*2O(l) \leftrightharpoons H*3O^+(aq) + CN^-(aq)$
Organic acids (containing the carboxyl group -COOH) are generally weak acids.
Example: Acetic acid ( $CH_3COOH$ ).
- $CH*3COOH(aq) + H*2O(l) \leftrightharpoons H*3O^+(aq) + CH*3COO^-(aq)$

Aqueous Solutions of Bases

Most bases are ionic compounds containing metal cations and the hydroxide anion, $OH^-$ .
Bases dissociate when dissolved in water.
When a base completely dissociates in water, the solution is strongly basic.
Example: Sodium hydroxide, NaOH.
- $NaOH(s) \longrightarrow Na^+(aq) + OH^-(aq)$
Group 1 elements (alkali metals) form alkaline (basic) solutions.
Ammonia, $NH_3$ , is a molecular base commonly used in household cleaners.
$NH*3(aq) + H*2O(l) \leftrightharpoons NH*4^+(aq) + OH^-(aq)$

Strength of Bases

The strength of a base depends on the extent to which it dissociates or adds hydroxide ions to the solution.
Strong base: completely dissociates into its ions in dilute aqueous solutions (strong electrolytes).
Example: Potassium hydroxide, KOH.
- $KOH(s) \longrightarrow K^+(aq) + OH^-(aq)$
The alkalinity of aqueous solutions depends on the concentration of $OH^-$ ions in solution.
Ammonia is highly soluble but is a weak electrolyte, thus a weak base.

Acid-Base Theories

Brønsted-Lowry acids and bases donate or accept protons.
A Lewis acid or base accepts or donates a pair of electrons.

Key Terms

Brønsted-Lowry acid: A molecule or ion that is a proton donor.
Brønsted-Lowry base: A molecule or ion that is a proton acceptor.
Brønsted-Lowry acid-base reaction: Protons are transferred from one reactant (the acid) to another (the base).
Monoprotic acid: An acid that can donate only one proton (hydrogen ion) per molecule.
Polyprotic acid: An acid that can donate more than one proton per molecule.
Diprotic acid: A polyprotic acid that can donate two protons per molecule.
Triprotic acid: A polyprotic acid that can donate three protons per molecule.
Lewis acid: An atom, ion, or molecule that accepts an electron pair to form a covalent bond.
Lewis base: An atom, ion, or molecule that donates an electron pair to form a covalent bond.
Lewis acid-base reaction: The formation of one or more covalent bonds between an electron-pair donor and an electron-pair acceptor.

Brønsted-Lowry Acids and Bases

A Brønsted-Lowry acid is a molecule or ion that is a proton donor (H^+}).
Example: $HCl + NH*3 \longrightarrow NH*4^+ + Cl^-$
A Brønsted-Lowry base is a molecule or ion that is a proton acceptor.

Monoprotic and Polyprotic Acids

Monoprotic acid: An acid that can donate only one proton per molecule.
Examples: Perchloric acid ( $HClO*4$ ), hydrochloric acid (HCl), and nitric acid ( $HNO*3$ ).
$HCl(g) + H*2O(l) \longrightarrow H*3O^+(aq) + Cl^-(aq)$
Polyprotic acid: An acid that can donate more than one proton per molecule.
Examples: Sulfuric acid ( $H*2SO*4$ ) and phosphoric acid ( $H*3PO*4$ ).
Ionization occurs in stages.
Sulfuric acid is a diprotic acid (donates two protons per molecule).
$H*2SO*4(l) + H*2O(l) \longrightarrow H*3O^+(aq) + HSO_4^-(aq)$
$HSO*4^-(aq) + H*2O(l) \leftrightharpoons H*3O^+(aq) + SO*4^{2-}(aq)$
Phosphoric acid is a **tri