Describing an AcidDescribing an Acid
Tastes “sour”Tastes “sour” Common compound in fruits and Common compound in fruits and
vegetablesvegetables corrosive corrosive Forms electrolytes when in aqueous Forms electrolytes when in aqueous
solution (ions!)solution (ions!) Is a molecular compoundIs a molecular compound
Explaining Acid BehaviorExplaining Acid Behavior
Acids are Acids are hydrogen containing hydrogen containing substancessubstances, HCl, H, HCl, H22SOSO44
But not all hydrogen containing But not all hydrogen containing compounds are acids!!! CHcompounds are acids!!! CH44, C, C66HH1212OO66
Dissociate (ionize) by releasing H+ ions Dissociate (ionize) by releasing H+ ions (hydrogen ion or proton) into solution.(hydrogen ion or proton) into solution.
written as a dissociation Rxwritten as a dissociation Rx HCl HCl →H→H++ + OH + OH--
Acid Formulas Acid Formulas
Acids are ionic compounds where the Acids are ionic compounds where the cationcation is is H+ (not a metal)H+ (not a metal)
Anion:Anion: Periodic table (how many +/-) and Periodic table (how many +/-) and Memory (polyatomic ions: nitrate, Memory (polyatomic ions: nitrate, hydroxide, carbonate, chlorate, sulfate, hydroxide, carbonate, chlorate, sulfate, phosphatephosphate
Undissociated it is a neutral compoundUndissociated it is a neutral compound
Acid FormulasAcid Formulas
Example: phosphoric acidExample: phosphoric acid Made of phosphate and enough H+ to Made of phosphate and enough H+ to
neutralize itneutralize it Formula of phosphate:Formula of phosphate: POPO44
3-3-
Plus 3 H+Plus 3 H+ HH33POPO44
Types of AcidsTypes of Acids
Contains/releases Contains/releases one ionizable H+one ionizable H+ , , monoprotic acidmonoprotic acid
HCl HCl → H+ + Cl-→ H+ + Cl-Contains/releases Contains/releases two ionizable H+two ionizable H+ , ,
diprotic aciddiprotic acid HH22SOSO44 → 2H+ + SO→ 2H+ + SO44
2-2-
Contains/releases Contains/releases three ionizable H+three ionizable H+ , , triprotic acidtriprotic acid
HH33POPO44 → 3H+ + PO→ 3H+ + PO443-3-
Review ElectronegativityReview Electronegativity
Increases in this directionIncreases in this direction
Why do acids release H+?Why do acids release H+? H involved in H involved in very polar covalent bondsvery polar covalent bonds
–attached to a very electronegative –attached to a very electronegative element are released as H+ ionselement are released as H+ ions
Example HCl: Cl is very electronegativeExample HCl: Cl is very electronegative
H-Cl ---H-Cl --- H H++ + Cl + Cl--
δδ+ + δδ-- On the other hand: CH4 weakly polar On the other hand: CH4 weakly polar
molecule: C is not very electronegative, molecule: C is not very electronegative, does not release an H+!!!does not release an H+!!!
What does the H+ do?What does the H+ do?
Reacts with HReacts with H22O to form an O to form an hydronium hydronium
ionion H H33O+O+
a. H+ + Ha. H+ + H22O O → → HH33OO+ +
Hydrochloric acid Hydrochloric acid (hydrogen chloride)(hydrogen chloride)
HClHCl MonoMonoprotic acidprotic acid
H - Cl H - Cl
HCl HCl → H→ H++ + Cl + Cl--
Carbonic AcidCarbonic Acid
HH22COCO33
Diprotic acidDiprotic acid HH22COCO3 3 →2→2H+ + COH+ + CO33
2-2-
Phosphoric AcidPhosphoric Acid
HH33POPO44
Triprotic acidTriprotic acid HH33POPO44 →3 →3 H+ + POH+ + PO44
3-3-
Sulfuric AcidSulfuric Acid
HH22SOSO44
Diprotic acidDiprotic acid HH22SOSO44→ 2H+ + → 2H+ + SOSO44
2-2-
Formulas of Organic Acids-Formulas of Organic Acids-Acids of HydrocarbonsAcids of Hydrocarbons
Example: CHExample: CH33COOHCOOH
Not all hydrogens are released!Not all hydrogens are released! Which bonds are high/low polarWhich bonds are high/low polar
very polarvery polar
Weak polarWeak polar Monoprotic Monoprotic
Organic Acids have Organic Acids have Carboxyl GroupsCarboxyl Groups
COOH group is called a COOH group is called a carboxyl groupcarboxyl group
Makes a molecule acidicMakes a molecule acidic Dissociation: Dissociation:
CHCH33COOHCOOH→→CH3COOCH3COO-- + H + H++
Ethanoic Acid (acetic or Ethanoic Acid (acetic or vinegar acid)vinegar acid)
CHCH33COOHCOOH monoprotic acidmonoprotic acid
CHCH33COOHCOOH→H+ +→H+ +CHCH33COOCOO--
B. Describing a BaseB. Describing a Base Adjective: Adjective: basicbasic or or alkalinealkaline rare in nature/foodsrare in nature/foods taste bittertaste bitter are part of soaps –make surfaces are part of soaps –make surfaces
slipperyslippery Corrosive, often more dangerous than Corrosive, often more dangerous than
acidsacids Are part of cleaners, drain openersAre part of cleaners, drain openers Act as electrolyte if aqueousAct as electrolyte if aqueous
Base FormulasBase Formulas
Normal ionic neutral compound: metal Normal ionic neutral compound: metal cation and hydroxide anion (OH-) cation and hydroxide anion (OH-)
Formula ends with OHFormula ends with OH Name ends with ‘hydroxide’Name ends with ‘hydroxide’ NaOH –sodium hydroxideNaOH –sodium hydroxide Give the formula of Calcium HydroxideGive the formula of Calcium Hydroxide Ca(OH)Ca(OH)22
Base BehaviorBase Behavior
Dissociation into metal cation and Dissociation into metal cation and hydroxide ionhydroxide ion, OH- , OH-
A base is a hydroxide donorA base is a hydroxide donor NaOH NaOH → Na+ + OH-→ Na+ + OH-
Sodium Hydroxide NaOHSodium Hydroxide NaOH
Ionic compound Ionic compound Releases OH-Releases OH- NaOH NaOH → Na+ + OH-→ Na+ + OH- Other similar base: KOH (potassium Other similar base: KOH (potassium
hydroxide), CsOH, RbOHhydroxide), CsOH, RbOH
Magnesium hydroxideMagnesium hydroxide
Mg(OH)Mg(OH)22
Mg(OH)Mg(OH)2 2 →→MgMg2+2+ + 2(OH) + 2(OH)--
Similar are Calcium- or BariumhydroxideSimilar are Calcium- or Bariumhydroxide
Ammonia NH3Ammonia NH3
Exceptional base:Exceptional base: Does not directly release OH-Does not directly release OH- Instead breaks water apartInstead breaks water apart NH3 + H2O NH3 + H2O → NH4+ + OH-→ NH4+ + OH-
Testing for Acids and Testing for Acids and BasesBases indicator substances that change colorindicator substances that change color Litmus paperLitmus paper Commercially available test stripsCommercially available test strips
Acids and Bases togetherAcids and Bases together
React with each otherReact with each other neutralizeneutralize form a salt of the base cation and the form a salt of the base cation and the
acid anion and wateracid anion and water
HCl + NaOHHCl + NaOH→ NaCl + H2O→ NaCl + H2O
Practice: Carbonic acid reacts with Calcium Practice: Carbonic acid reacts with Calcium hydroxidehydroxide
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