Acids and BasesAcids and Bases

General FormulaGeneral Formula

ACID + BASE ACID + BASE H H22O + SALTO + SALT

A salt is A salt is anan

ionic ionic

compoundcompound

Comparing Acids to BasesComparing Acids to Bases

Naming and Writing Formulas

Acids

A compound that contains one or more hydrogen atoms and produces hydrogen ions (H+) when dissolved in water

Acids consist of an anion and as many H+ as are necessary to make the atom electrically neutral.

HnX

Arrhenius Acids and BasesArrhenius Acids and Bases

In water, an Arrhenius acid produces HIn water, an Arrhenius acid produces H33OO++, , and an Arrhenius base produces OHand an Arrhenius base produces OH--

Arrhenius’ theory showed why acids and bases:Arrhenius’ theory showed why acids and bases:1.1. have similar propertieshave similar properties2.2. neutralize each otherneutralize each other3.3. produce water and salt when they combineproduce water and salt when they combine

Arrhenius’ theory could not show:Arrhenius’ theory could not show:1.1. Why compounds without OH- could act as basesWhy compounds without OH- could act as bases2.2. Why reactions were not limited to occurring in Why reactions were not limited to occurring in

waterwater

Bronsted-Lowry Acids and Bronsted-Lowry Acids and BasesBases

According to Bronsted-Lowry theory, According to Bronsted-Lowry theory, acids are proton (Hacids are proton (H++) donors and bases ) donors and bases are proton acceptors (opposite of an acid)are proton acceptors (opposite of an acid)

Protons form hydronium ions, HProtons form hydronium ions, H33OO++, in , in water when they bond to polar water water when they bond to polar water moleculesmolecules

This theory:This theory:1.1. expands the number of substance that can expands the number of substance that can

be acids and basesbe acids and bases

2.2. Explains how substances without OHExplains how substances without OH-- can be can be basesbases

Naming AcidsNaming AcidsWhen an acid dissolves in water and When an acid dissolves in water and

a hydrogen ion and a simple non metal are a hydrogen ion and a simple non metal are formedformed

HCl + HHCl + H22O O H H33OO++ + Cl + Cl--

hydrogen + water hydrogen + water hydronium + chloride hydronium + chloride

chloride ion ionchloride ion ion

1.1. Use the prefix Use the prefix hydrohydro in front of the nonmetalin front of the nonmetal

2.2. Change the nonmetal’s ending from Change the nonmetal’s ending from ideide to to ic ic acidacid

HClHCl(aq)(aq) is called is called hydrohydrochlorchloricic acidacid

When an acid contains a polyatomic ion, the name of the When an acid contains a polyatomic ion, the name of the acid comes from the name of the polyatomic ion. acid comes from the name of the polyatomic ion.

* the prefix * the prefix hydrohydro is is notnot used to indicate a polyatomic ion is present used to indicate a polyatomic ion is present

Polyatomic ions with an Polyatomic ions with an ateate ending……..change to ending……..change to ic acidic acid

HNOHNO3(aq)3(aq) + H + H22OO(l)(l) H H33OO++ + NO + NO33--

NitrNitricic acidacid + water + water hydronium + nitr hydronium + nitrateate

ion ionion ion

Polyatomic ions with an Polyatomic ions with an iteite ending……..change to ending……..change to ous ous acidacid

HNOHNO2(aq)2(aq) + H + H22OO(l)(l) H H33OO++ + NO + NO22--

NitrNitrous acidous acid + water + water hydronium + nitr hydronium + nitriteite

ion ionion ion

Naming and Writing Formulas

Naming Acids

1) When the anion’s name ends in -ide, the acid’s name begins with hydro- and the stem of the anion’s name ends in -ic, followed by the word acid.

Example:

Hydrochloric Acid HCl

Anion: Chloride Cl-

Naming and Writing Formulas

Naming Acids

2) When the anion’s name ends in -ite, the acid’s name is the stem of the anion with the suffix -ous, followed by the word acid.

Example: Sulfurous Acid H2SO3

Anion: Sulfite SO32-

Naming and Writing Formulas

Naming Acids

3) When the anion’s name ends in -ate, the acid’s name is the stem of the anion with the suffix -ic, followed by the word acid.

Example: Nitric Acid HNO3

Anion: Nitrate NO3-

Naming and Writing FormulasWriting Formulas for Acids

Use the rules for naming acids in reverse to write formulas for acids.

Find the anion in the acid. Then, match its charge with the appropriate number of H+ ions to make the formula electrically neutral.

Naming BasesNaming Bases

Name the metal (cation) by its Name the metal (cation) by its elemental nameelemental name

Name the simple nonmetal (anion) Name the simple nonmetal (anion) with the with the ideide ending ending

Name the polyatomic ion as is Name the polyatomic ion as is (example OH(example OH-- is hydroxide) is hydroxide)

An ionic compound that produces hydroxide ions (OH-) when dissolved in water.

These are named in the same way as other ionic compounds: cation first and anion second.

Common Bases

NaOH Sodium Hydroxide

Ba(OH)2 Barium Hydroxide

Ca(OH)2 Calcium Hydroxide

Names and Formulas for Bases

pH Scale The amount

of H3O+ ions in solution determines whether a solution is an acid or base.

pH measures the concentrationof H+ ions in a solution

pH ScalepH Scale

StrongStrong ACIDSACIDS weakweak weakweak BASESBASES strongstrong

1 2 3 4 5 6 1 2 3 4 5 6 7 7 8 9 10 11 12 13 8 9 10 11 12 13 1414

neutralneutral

1010-1 -1 1010-7 -7 1010-14-14

Concentration of H3O+ ions (moles/litre)

Acids increase Bases decreasep+ concentration p+

concentration

In aqueous solution, a strong acid donates nearly all of its protons to water, whereas a weak acid donates only a small percentage of protons to water.

Most hydroxides of Groups 1A and 2A are strong gases, which dissociate nearly completely in water

Adding water equalizes the strength of all strong acids/bases = levelling effect

Conjugate PairsConjugate Pairs Acids and bases react differently but are connected Acids and bases react differently but are connected

in similar reactionsin similar reactions Once an acid donates a proton it is then able to Once an acid donates a proton it is then able to

accept another protonaccept another proton = conjugate acid-base pair (strengths are inverse)= conjugate acid-base pair (strengths are inverse)

PracticePractice

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