Key TermsAcidity - the level of acid in substances Arrhenius acid - a substance containing hydrogen that, when

dissolved in water, increases the concentration of H+ ionsArrhenius base - any substance that ionizes when it dissolves in

water to give the OH- ionBronsted-Lowry acid - proton donorBronsted-Lowry base - proton acceptor Conjugate acid - the compound formed when a base gains a

protonConjugate base - the compound formed when an acid loses a

protonHydrogen ion - a positively charged atom of hydrogenHydronium ion - the ion H3O+

Hydroxide ion - the OH- ion Ionization - the condition of being dissociated into ionsKw - is the constant for the self-ionization of water

Key TermsNeutralization reaction - a chemical reaction in which an acid and a

base interact with the formation of a saltpH - a figure expressing the acidity or alkalinity of a solution on a

logarithmic scalepH scale: 0-14pOH - the reciprocal of the logarithm of the hydroxide ion

concentrationSalt - a chemical compound formed from the reaction of an acid with

a baseStrong acid - an acid that ionizes completely in an aqueous solutionStrong base - a base that dissociates completely into a metal ion and

hydroxide ion in aqueous solutionWeak acid - an acid that dissociates incompletely Weak base - a chemical base that does not ionize fully in an aqueous

solution

SaltsIonic compounds that result from acid-base neutralization

Many, but not all, are soluble

Soluble salts dissociate in water and will conduct electricity

Soluble salts that conduct electricity in solution are electrolytes

Insoluble salts are non-electrolytes

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Nature of Acids and BasesThere are three broad categories of acids and

bases and the nature of each is defined by the category

Arrhenius – based on specific ions dissolved in water

Brǿnsted-Lowry – based on behavior associated with protons

Lewis (Not covered in this course)

Arrhenius AcidsCompounds that dissociate in water to produce

hydrogen ions (H+)

The hydrogen ions bond to the water molecules to form hydronium ions (H3O+)

Examples of Arrhenius acidsHClH2SO4

HNO3

HC2H3O2

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Arrhenius BasesCompounds that dissociate in water to

produce hydroxide ions (OH-)

Examples of Arrhenius basesNaOHKOH

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Properties of Acids & Bases  Acids Bases

IonsDissociates to produce

H3O+ ionsDissociates to produce OH- ions

Taste Sour BitterFeel Not slippery SlipperypH < 7 > 7Electrical Conductivity Conducts current Conducts current

Reactivity with metalsReacts with active

metals to produce H2 (g)

Does not react with metals

Color with Litmus indicator

Red Blue

Color with phenolphthaleinindicator

Clear Pink

Brǿnsted-Lowry AcidMore broad definition of acid

Includes any substance that reacts in a particular reaction to produce protons (H+) – proton donor

Includes Arrhenius Acids

Brǿnsted-Lowry BaseMore broad definition of base

Also include any substance that reacts in a particular reaction to accept protons (H+) – proton acceptor

Includes Arrhenius Bases

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Brǿnsted-Lowry Acid-Base Reaction NH3 + H2O ↔ NH4

+ + OH- (Base) (Acid) (Conjugate Acid) (Conjugate Base)

The water donates a H+ to the ammonia and is therefore the acid

The ammonia accepts the H+ from the water and is therefore the base

These reactions are reversible and the ammonium is consider the conjugate acid as it will be the donor (acid) in the reverse direction

Likewise the hydroxide will be the acceptor (base) in the reverse reaction and is the conjugate base

Naming Arrhenius Acids & BasesArrhenius Bases follow the naming rules for ionic

compounds. All of these are hydroxide compounds using different metal ions.

Arrhenius Acids are named using a new set of rules as these are all unusual covalent compounds that dissociate in water

Rules for Binary Acids – acids with only two elements

Rules for Ternary Acids – acids with polyatomic ions

Naming Binary Arrhenius AcidsArrhenius Acids involving only two types of

atoms have the prefix “hydro” and the suffix “ic”.

H2S has only hydrogen atoms and sulfur atoms

Hydro-sulfur-ic → Hydrosulfuric Acid

HBr has only hydrogen atoms and bromine atoms

Hydro-bromine-ic → Hydrobromic Acid

Naming Ternary Arrhenius Acids Arrhenius Acids involving a polyatomic ion are named according

to the polyatomic ion as follows:

When an ion ending in “ate” is present with no “per” prefix , the acids are named after the non-oxygen atom and uses the suffix “ic” H3PO4 has a phosphate polyatomic ion

Phosphor-ic Phosphoric Acid

When an ion ending in “ite” is present with no “hypo” prefix, the acids are named after the non-oxygen atom and uses the suffix “ous” HClO2 has a chlorite polyatomic ion chlor-ous Chlorous Acid

When an ion ending in “ate” is present with “per” prefix , the acids are named after the non-oxygen atom with “per” as the prefix and the suffix “ic”

Ions ending in “ite” with “hypo” prefix are named after the non-oxygen atom with “hypo” prefix and the suffix “ous”

Anion prefix

Anion suffix

Acid prefix Acid suffix Example

per ate per ic acid perchloric acid (HClO41-)

ate ic acid chloric acid (HClO31-)

ite ous acid chlorous acid (HClO21-)

hypo ite hypo ous acid hypochlorous acid (HClO1-)

ide hydro ic acid Hydrochloric acid (HCl)

Auto-Ionization of Water - KwWater partially auto-ionizes to form an equal number of

hydrogen ions and hydroxide ions

Kw is the numerical value associated with process and is referred to as the equilibrium constant for water and is the basis of the pH scale

Kw = (concentration of H+) (concentration of OH+) = (1 x 10-7) (1 x 10-7)

Kw = [H+] [OH+] = 1 x 10-14

This constant means that for any solution, if the hydrogen ion concentration or hydroxide ion concentration is known it is simple to calculate the other.

pHMeasures the acidity and basicity of a

solution

Represents the relative concentration of hydrogen and hydroxide ions

Used to simplify discussions concerning the amount of acid or base in the solution

Uses a logarithmic scale

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pH ScaleRanges from zero to 14

<7 = acid (more hydrogen ions than in water)>7 = base (less hydrogen ions than in water)7 = neutral (same concentration of hydrogen ions

as in water)

The concentration of both ions in water is 10-7 M which corresponds to a pH of 7 - neutral

A difference in pH corresponds to a difference in concentration of a factor by a factor of 10 difference in pH of 1 corresponds to a difference in

concentration of a factor of 101 or 10 difference in pH of 2 corresponds to a difference in

concentration of a factor of 102 or 100 difference in pH of 3 corresponds to a difference in

concentration of a factor of 103 or 1000

pH CalculationpH = - log [H+] [H+] = 10-pH

Since the equation for calculating pH has a negative sign, a low pH corresponds to a higher concentration

pOH = - log [OH-] [OH-] = 10-pOH

pH + pOH = 14 - log 10-7 M + -log 10-7 M = 14 Water 7 + 7 = 14

pH IndicatorspH indicators are made using weak acids or

bases

All pH indicators have a characteristic color change based on the pH of a solution

Different pH indicators are useful in different portions of the pH scale Some indicators like litmus can distinguish

solutions as acid or baseOthers are used to determine how acidic or

how basic a solution is

pH Indicator Ranges & Colors

Strong Acids & Weak AcidsStrong Bases & Weak BasesStrong Acids and Strong Bases completely, or

nearly completely, ionize in water making them excellent conductors of electricity

Acids – Hydrochloric, sulfuric, nitric Bases – Sodium hydroxide, potassium hydroxide

Weak Acids and Weak Bases only partially ionize in water making them poor conductors of electricity

Acids – Acetic, phosphoric, carbonic Bases – Ammonia, baking soda

Neutralization ReactionsReactions between strong Arrhenius acids and strong Arrhenius

bases

The products are water and a salt. The water forms from the hydrogen and hydroxide ions present. The salt is formed from the remaining ions of the acid and base.

The degree of neutralization is dependent on the amount and concentration of the acid and base

If the amounts and concentrations result in an equal number of moles of both, the resulting solution is neutral.

If the salt formed is insoluble, it will settle to the bottom as a precipitate.

If the salt is soluble, it will remain in a diluted solution.

Neutralization Reactions

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Differentiating Reaction CategoriesReduction-Oxidation

Combustion reactions Synthesis reactions involving an element reactant Decomposition reactions producing an element product Single-Replacement reactions

Precipitation Single-Replacement reactions involving metal elements Double-Replacement reactions forming an insoluble

product Acid-Base Neutralization reactions forming an

insoluble salt

Acid-Base Neutralization of Strong Acids & Bases Reactions involving strong Arrhenius acids and bases forming water

and a salt

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