Acids & BasesSC7. Students will characterize the properties that SC7. Students will characterize the properties that

describe solutions and the nature of acids and bases. describe solutions and the nature of acids and bases. b. Compare, contrast, and evaluate the nature of acids and bases: b. Compare, contrast, and evaluate the nature of acids and bases: • • Arrhenius, Bronsted-Lowry Acid/Bases Arrhenius, Bronsted-Lowry Acid/Bases • • Strong vs. weak acids/bases in terms of percent dissociation Strong vs. weak acids/bases in terms of percent dissociation • • Hydronium ion concentration Hydronium ion concentration • • pH pH • • Acid-Base neutralizationAcid-Base neutralization

Properties• Properties of AcidsProperties of Acids::

– Sour TasteSour Taste

– ElectrolytesElectrolytes

– Change indicator colorsChange indicator colors

– React with metals to React with metals to form hydrogenform hydrogen

– React with carbonates to React with carbonates to form carbon dioxideform carbon dioxide

– React with bases to form React with bases to form salt & watersalt & water

• Properties of basesProperties of bases::– BitterBitter

– Feel SlipperyFeel Slippery

– ElectrolytesElectrolytes

– Change indicator Change indicator colorscolors

– React with acids to React with acids to produce salt & waterproduce salt & water

What Are Acids?• DefinitionsDefinitions

• Arrhenius acidArrhenius acid: Produce H: Produce H+ + ionion• Arrhenius baseArrhenius base: Produce OH: Produce OH- - ionion• Bronsted-Lowery AcidBronsted-Lowery Acid: H: H++ donor donor• Bronsted Lowery BaseBronsted Lowery Base: H: H++ acceptor acceptor• **More Broad definition than Arrhenius****More Broad definition than Arrhenius**• Lewis acidLewis acid- can accept pr of e- to form a covalent bond (H- can accept pr of e- to form a covalent bond (H++))• Lewis baseLewis base- can donate pr of e- to form a covalent bond (OH- can donate pr of e- to form a covalent bond (OH--) )

– Look for lone prLook for lone pr– ** is more broad than other two def** is more broad than other two defAmphotericAmphoteric- can be acid or base- can be acid or base

Arrhenius acid Arrhenius acid

• Acids Form H+ Ions when Dissolved in Acids Form H+ Ions when Dissolved in WaterWater

Ex Ex HCl + HHCl + H220 0 ddHH++ + Cl + Cl-- + H + H2200

Actually it forms HActually it forms H33OO++ & Cl & Cl--

HCl +HHCl +H22O O

HH22SOSO44+2H+2H22O O

HH33OO++ + Cl + Cl--

2H2H33OO+++ SO+ SO44-2-2

Monoprotic Acid- Produces 1 Hydrogen Ion

Di-protic acids-

Produces 2 Hydrogen Ions

Hydrogen Ion concentration can be measured in molarity

Hydronium IonConcentration

• H+ or HH+ or H33O ion concentration can be O ion concentration can be

measured in molaritymeasured in molarity– Depends on # of Hydrogen Ions per Mole of Depends on # of Hydrogen Ions per Mole of

Acid.Acid.– Monoprotic 1x HClMonoprotic 1x HCl

– Diprotic 2x HDiprotic 2x H22SOSO44

– Triprotic 3x HTriprotic 3x H33POPO44

More on That Later?More on That Later?

Arrhenius BaseArrhenius Base

• Form a Hydroxide Ion (OHForm a Hydroxide Ion (OH--) During ) During SolvationSolvation

• NaOH + HNaOH + H22O O d d NaNa++ + OH + OH-- + H + H22OO

• Name Bases according to Ionic RulesName Bases according to Ionic Rules– Most are hydroxidesMost are hydroxides

• NaOH – sodium hydroxideNaOH – sodium hydroxide

• OHOH-- Ion Concentration can also be Ion Concentration can also be measured in Molaritymeasured in Molarity

NeutralizationNeutralization

• - Double displacement Reaction- Double displacement Reaction– Acid + Base Acid + Base salt + water salt + water– Nitric acid & calcium hydroxideNitric acid & calcium hydroxide– Sulfuric acid & aluminum hydroxideSulfuric acid & aluminum hydroxide– Can find acid & base that form saltCan find acid & base that form salt

• NaCl NaCl

• NaHCONaHCO33

Self Ionization Of Water

• HH22O (HOH) can self Ionize into a HO (HOH) can self Ionize into a H++ & an OH & an OH--

• HH22O + HO + H22O O H H33OO++ + OH + OH--

– Hydronium ion HHydronium ion H33OO++ – Hydroxide ion OHHydroxide ion OH--

• Only 1X 10 Only 1X 10 –14–14 M of water molecules do this so M of water molecules do this so [H[H33OO++][OH][OH--] = 1X 10 ] = 1X 10 –14–14 M M – If [HIf [H33OO++]=[OH]=[OH--] neutral solution] neutral solution– If [HIf [H33OO++]>[OH]>[OH--] acidic solution] acidic solution– If [HIf [H33OO++]<[OH]<[OH--] basic or alkaline solution] basic or alkaline solution

Ionization Constants

• A constant (k), is a quantitative measure of the strength of A constant (k), is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a an acid in solution. It is the equilibrium constant for a chemical reaction known as dissociationchemical reaction known as dissociation

• HA HA HH++ + A + A--

][

][][

HA

AHka

Strengths of Acids and Bases

• The strength of an acid or a base, is a measure The strength of an acid or a base, is a measure of how many ions are formed when dissolved of how many ions are formed when dissolved in waterin water

• Strong Acids Disassociate completelyStrong Acids Disassociate completely

• Weak Acids do not completely DisassociateWeak Acids do not completely Disassociate– Weak acids have KWeak acids have Ka a

Strong Acids & Bases

• AcidsAcids• HClHCl• HBrHBr• HIHI• HNO3HNO3• H2SO4H2SO4• HClO3HClO3• HClO4HClO4

• Bases• LiOH• NaOH• KOH• RbOH• CsOH• Ca(OH)22

• Sr(OH)2

• Mg(OH)2

pH Scale

• pH=-Log[H3O]

• pOH=-log[OH-]

• pH+pOH=14

pH 1-6 7 8-14pH 1-6 7 8-14Acid neutral baseAcid neutral base

pOH 14-8 7 6-1pOH 14-8 7 6-1pH +pOH=14pH +pOH=14

Use to find one given the other.Use to find one given the other.Find the pOH if the pH is 8.2.Find the pOH if the pH is 8.2.

Calculate the pH of a solution of HCl if Calculate the pH of a solution of HCl if the [Hthe [H33O+] is 0.234 MO+] is 0.234 M

1)1) A 0.001 M solution of HClA 0.001 M solution of HCl2)2) A 0.09 M solution of HBr A 0.09 M solution of HBr 3)3) A 1.34 x 10-4 M solution of HClA 1.34 x 10-4 M solution of HCl4)4) A 2.234 x 10-6 M solution of HI A 2.234 x 10-6 M solution of HI 5)5) A 7.98 x 10-2 M solution of HNO3 A 7.98 x 10-2 M solution of HNO3