Acids and Bases

Properties of Acids and Bases

Properties of Acids

Properties of Bases

Conduct electricity(some are strong electrolytes, others are weak)

Change indicators(blue litmus to red, Bromothymol blue to yellow

React with metals to form hydrogen gas

React with hydroxides to form a salt and water

taste bitter; feel slippery

taste sour when consumed

Change indicators red litmus turns blue; Bromothymol blue remains blue; Phenolphatein turns pink

Conduct electricity(some strong, some weak)

React with acids to form water and a salt

Types of acids

Binary acids

Oxyacids

Ionizable acids

Polyprotic acids

Monoprotic acids

An acid that contains hydrogen and a highly electronegative element such as fluorine(ex: HF, HBr, HCl, HI

A acid that contains three elements; usually hydrogen, oxygen and a nonmetal

An acid that can only donate one proton/hydrogen ion per molecule(ex: HCl, HNO3, HPO4)

Acids that contain more than one ionizable hydrogen ion(ex: Methane, Acetic acid, Phosphoric acid)

Only hydrogens that are highly polar can be ionizable,meaning their bonded to a highly electronegative element

After each ionization, the strength of the acid gets weaker since the polarity of the bonds decreases

Common Industrial Acids

Phosphoric Acid: Essential for plants and animals; mostly used for manufacturing fertilizers; used as a flavoring agent in beverages

Hydrochloric acid: Important for "pickling"; used as a general cleaning agent in food processing

Nitric Acid: Stains proteins yellow; used for making explosives; a volatile, unstable liquid so dissolving it in water makes it more stable

Acetic Acid: Can form crystals in a cold room; used in manufacturing plastics; raw material in food production supplements

Sulfuric acid: used in large quantities in petroleum; essential for production of metals; automobile batteries; can be used to remove water from gases making it a great dehydrating agent

Acid/Base Definitions

Arrhenius

BrØnsted-Lowry

Lewis

Arrhenius Acid: A compound that increases the number of hydrogen ions in the solution forms a hydronium ion(H3O)

Arrhenius Base: A substance that increases the number of hydroxide(OH-) ions present in the solution

Arrhenius acids are compounds with ionizable hydrogens; their water solutions are aqueous acids which are all electrolytes

Water molecules attract the hydrogens from the acids since they are polar, which is why the stronger polarity = > ionizable

BrØnsted-Lowry Acids: Acids that are proton donors(ex: HCl + NH3 -> NH4Cl)

Acids are proton donors while bases are proton acceptors

In a reaction, the proton is transferred from the acid to the base from reactant to product

Lewis Acids accepts an electron pair to form a covalent bond; based on the bonding structure; don't contain any hydrogen at all; are the broadest of the three definitions

Any substance that can accept electron pairs are lewis acids including hydrogen protons or elements such as silver; can apply to substances in any phase

Lewis acids are electron pair acceptors while lewis bases are electron pair donors

Lewis Acid-base reaction: The formation of one or more covalent bonds between an electron pair donor and acceptor

Strength of Acids and Bases

Strength of Acids

Strength of Bases

Strong acids

Weak acids

Strong acids completely ionize in solution(ex: HClO4, HCl, HNO3)

Strength depends on the polarity of the bonds between the hydrogen and the electronegative element, and the bond energy

Acids that only dissolve partial amounts of their hydrogens; solution will contain hydronium ions, dissolved acid molecules and anions(ex: HCN)

Acid dissociation constant

A reversible ionization makes a reversible reaction; creates the acid dissociation constant that describes the concentration of the anion and acid

Strong bases

Weak bases

Strong bases depend on the extent of ionization of hydroxide ions or how much the base dissociates; strong bases = strong electrolytes(ex: KOH)

Example of a weak base: Ammonia + water -> <- ammonia + hydroxide(reversible reaction)

Weak bases are reversible reactions since they ionize only partially

Base Dissociation Constant

Base dissociation constant measures the strength of a base dissolved in water; not very soluble bases don't produce large quantities of hydroxide ions

Weak bases form an equilibrium with their ions; strong bases dissociate completely; stronger base = larger Kb value

Acid-base reactions

Conjugate acids and bases

Conjugate base: the remainder of an acid after it donates its proton

Conjugate acid: A substance that is formed after a Bronsted-lowry base gains a proton

General equation: Acid + base --> conjugate acid + conjugate base

strength of the conjugate acid/base depends on the strength of the acid/base

the stronger the acid, the weaker the conjugate base; stronger the base, the weaker the conjugate acid

proton transfer reactions favor the weaker side(concentration would be greater)