Acids & Bases SC7. Students will characterize the properties that describe solutions and 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 neutralization Acid-Base neutralization

Properties Properties of Acids:Properties of Acids: –Sour Taste –Electrolytes –Change indicator colors –React with metals to form hydrogen –React with carbonates to form carbon dioxide –React with bases to form salt & water Properties of bases:Properties of bases: –Bitter –Feel Slippery –Electrolytes –Change indicator colors –React with acids to produce salt & water

What Are Acids? DefinitionsDefinitions Arrhenius acid: Produce H + ion Arrhenius acid: Produce H + ion Arrhenius base: Produce OH - ionArrhenius base: Produce OH - ion Bronsted-Lowery Acid: H + donorBronsted-Lowery Acid: H + donor Bronsted Lowery Base: H + acceptorBronsted Lowery Base: H + acceptor **More Broad definition than Arrhenius****More Broad definition than Arrhenius** Lewis acid- can accept pr of e- to form a covalent bond (H + )Lewis acid- can accept pr of e- to form a covalent bond (H + ) Lewis base- can donate pr of e- to form a covalent bond (OH - )Lewis base- can donate pr of e- to form a covalent bond (OH - ) –Look for lone pr –** is more broad than other two def Amphoteric- can be acid or base

Arrhenius acid Acids Form H+ Ions when Dissolved in WaterAcids Form H+ Ions when Dissolved in Water Ex HCl + H 2 0 dH + + Cl - + H 2 0 Actually it forms H 3 O + & Cl -

HCl +H 2 O  H 2 SO 4 +2H 2 O  H 3 O + + Cl - 2H 3 O + + SO 4 -2 Monoprotic Acid- Produces 1 Hydrogen Ion Di-protic acids- Produces 2 Hydrogen Ions Hydrogen Ion concentration can be measured in molarity

Hydronium Ion Concentration H+ or H 3 O ion concentration can be measured in molarityH+ or H 3 O ion concentration can be measured in molarity –Depends on # of Hydrogen Ions per Mole of Acid. –Monoprotic 1x HCl –Diprotic 2x H 2 SO 4 –Triprotic 3x H 3 PO 4 More on That Later?

Arrhenius Base Form a Hydroxide Ion (OH - ) During SolvationForm a Hydroxide Ion (OH - ) During Solvation NaOH + H 2 O d Na + + OH - + H 2 ONaOH + H 2 O d Na + + OH - + H 2 O Name Bases according to Ionic RulesName Bases according to Ionic Rules –Most are hydroxides NaOH – sodium hydroxideNaOH – sodium hydroxide OH - Ion Concentration can also be measured in MolarityOH - Ion Concentration can also be measured in Molarity

Neutralization - Double displacement Reaction- Double displacement Reaction –Acid + Base  salt + water –Nitric acid & calcium hydroxide –Sulfuric acid & aluminum hydroxide –Can find acid & base that form salt NaClNaCl NaHCO 3NaHCO 3

Self Ionization Of Water H 2 O (HOH) can self Ionize into a H + & an OH -H 2 O (HOH) can self Ionize into a H + & an OH - H 2 O + H 2 O  H 3 O + + OH -H 2 O + H 2 O  H 3 O + + OH - –Hydronium ion H 3 O + –Hydroxide ion OH - Only 1X 10 –14 M of water molecules do this so [H 3 O + ][OH - ] = 1X 10 –14 MOnly 1X 10 –14 M of water molecules do this so [H 3 O + ][OH - ] = 1X 10 –14 M –If [H 3 O + ]=[OH - ] neutral solution –If [H 3 O + ]>[OH - ] acidic solution –If [H 3 O + ]<[OH - ] basic or alkaline solution

Ionization Constants A constant (k), is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a chemical reaction known as dissociationA constant (k), is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a chemical reaction known as dissociation HA  H + + A -HA  H + + A -

Strengths of Acids and Bases The strength of an acid or a base, is a measure of how many ions are formed when dissolved in waterThe strength of an acid or a base, is a measure of how many ions are formed when dissolved in water Strong Acids Disassociate completelyStrong Acids Disassociate completely Weak Acids do not completely DisassociateWeak Acids do not completely Disassociate –Weak acids have K a

Strong Acids & Bases AcidsAcids HClHCl HBrHBr HIHI HNO3HNO3 H2SO4H2SO4 HClO3HClO3 HClO4HClO4 Bases LiOH NaOH KOH RbOH CsOH 2Ca(OH) 2 Sr(OH) 2 Mg(OH) 2

pH Scale pH=-Log[H 3 O] pOH=-log[OH - ] pH+pOH=14 pH Acid neutral base pOH pH +pOH=14 Use to find one given the other. Find the pOH if the pH is 8.2.

Calculate the pH of a solution of HCl if the [H 3 O+] is M 1)A M solution of HCl 2)A 0.09 M solution of HBr 3)A 1.34 x 10-4 M solution of HCl 4)A x 10-6 M solution of HI 5)A 7.98 x 10-2 M solution of HNO3