Presentation on theme: "14.1 Properties of Acids and Bases"— Presentation transcript:
1 14.1 Properties of Acids and Bases Chapter 14 Acids & Bases14.1 Properties of Acids and Bases
2 Properties of Acids Aqueous solutions have a sour taste Some acids react with active metals to release hydrogen:Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g)Acids react with bases to produce salts and water:HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)Acids conduct electric current
3 Properties of Acids Acids change the color of acid-base indicators: Blue litmus turns redMethyl orange turns redHave a pH of less than 7Donate protons, H+React with carbonatesNeutralize bases
5 Review: Acids Nomenclature Binary acids - acids that contain two different elements: hydrogen and one of the more-electronegative elementsprefix "hydro-"Root of element name"-ic" endingexample: HBr = hydrobromic acidOxyacids - compounds of hydrogen, oxygen, and a third element, usually a nonmetalno prefixes
7 Some Common Industrial Acids Sulfuric AcidHighest volume production of any chemical in the U.S.Used in the production of paper, fertilizers, petroleum refining & car batteries
8 Some Common Industrial Acids Nitric AcidUsed in the production of rubber, plastics, pharmaceuticals, fertilizers & explosivesNitric acid is a volatile acid – its reactive components evaporate easilyStains proteins yellow (including skin!)
9 Some Common Industrial Acids Hydrochloric AcidUsed in the pickling of steelUsed to purify magnesium from sea waterUsed to correct swimming pool pHPart of gastric juice, it aids in the digestion of proteinSold commercially as “Muriatic acid”
10 Some Common Industrial Acids Phosphoric AcidA flavoring agent in sodasUsed in the manufacture of detergents & fertilizersNot a common laboratory reagent
11 Some Common Industrial Acids Acetic AcidConcentrated “glacial” acetic acid used in the manufacture of plasticsUsed in making pharmaceuticalsAcetic acid is the acid present in vinegar
12 Properties of Bases Aqueous solutions of bases have a bitter taste Bases change the color of acid-base indicatorsTurns red litmus blueTurns phenolphthalein magenta/purpleDilute aqueous solutions of bases feel slipperyBases react with acids to produce salts and waterBases conduct electric currentAre proton, H+, acceptorsHave a pH value of greater than 7Neutralize acids
13 Arrhenius Acids & Bases A chemical compound that increases the concentration of hydrogen ions, H+, in aqueous solutionArrhenius BaseA substance that increases the concentration of hydroxide ions, OH-, in aqueous solutionSwedish Chemist
14 Aqueous Solutions of Acids Acids are molecular compounds that ionize in solutionHNO3 + H2O → H3O+ + NO3-H2SO4 + H2O → H3O+ + HSO4-H2O + HCl → H3O+ + Cl-Proton DonorProton Acceptor
15 Ionization Equations Instead of: HCl (g) + H2O (l) → H3O+ (aq) + Cl- (aq)Sometimes we write this:HA + H2O (l) → H3O+ (aq) + A- (aq)Or even this:HCl (aq) → H+ (aq) + Cl- (aq)Generic formulasLeave out water
16 Strength of Acids Strong acids completely ionize in solution. (100%) Weak acids ionize only slightly and are weak electrolytes.(<5%)
19 Strength vs. Concentration Strength refers to ionization in solution.Concentration refers to the amount of solute in solution.It is possible to have a concentrated solution of a weak acid or base.It is also possible to have dilute solution of a strong acid or base.
20 Organic AcidsOrganic acids all contain the “carboxyl” group, sometimes several of them.The carboxyl group is a poor proton donor, so ALL organic acids are weak acids.
21 Examples of Organic Acids Citric acid in citrus fruitMalic acid in sour applesDeoxyribonucleic acid, DNAAmino acids, the building blocks of proteinLactic acid in sour milk and sore musclesButyric acid in rancid butter
22 Aqueous Solutions of Bases Ionic bases dissociate when placed in water:NaOH (s) + H2O (l) → Na+ (aq) + OH- (aq)Basic solutions are referred to as “alkaline”Molecular bases produce hydroxide ions through a reaction with water:NH3 (g) + H2O (l) → NH4+ (aq) + OH- (aq)
23 Strength of Bases Strength of ionic bases in related to solubility: High solubility = strong baseLow solubility = weak baseMolecular bases tend to be weak regardless of solubility
25 Bronsted-Lowry Acids & Bases A molecule or ion that is a proton donorBronsted-Lowry Base:A molecule or ion that is a proton acceptorex: hydroxide ion is the acceptor portion of the ionic base, not the whole compound itselfBronsted-Lowry Acid-Base Reaction:A reaction in which protons are transferred from the acid to the base.
26 Types of Acids Monoprotic Acids: HC2H3O2 HCl Diprotic Acid: H2SO4 Can donate 1 HMonoprotic Acids: HC2H3O2HClDiprotic Acid: H2SO4Triprotic Acids: H3C6H5O H3PO4* Each successive proton is harder to remove!Can donate 2 HsCan donate 3 HsPolyprotic Acids
27 Lewis Acids & Bases Lewis Acid: An atom, ion or molecule that accepts an electron pair to form a covalent bondLewis Base:An atom, ion or molecule that donates an electron pair to form a covalent bondLewis Acid-Base Reaction:The formation of one or more covalent bonds between an electron-pair donor and electron-pair acceptor.This definition can be applied to phases other than aqueous reactions.
29 Conjugate Acids & Bases Conjugate BaseThe species that remains after an acid has given up its protonH3PO4 (aq) + H2O (l) ↔ H3O+ (aq) + H2PO4- (aq)The stronger the acid, the weaker its conjugate baseAcidConjugate Base
30 Conjugate Acids & Bases The species that is formed when a base gains a protonH3PO4 (aq) + H2O (l) ↔ H3O+ (aq) + H2PO4- (aq)The stronger the base, the weaker its conjugate acidBaseConjugate Acid
31 Proton-Transfer Reactions These reactions favor the production of the weaker acid and the weaker base.
32 Amphoteric CompoundsAny species that can act as either an acid or a baseEx: Water as a base:H3PO4 (aq) + H2O (l) ↔ H3O+ (aq) + H2PO4- (aq)Ex: Water as an acid:NH3 (g) + H2O (l) ↔ NH4+ (aq) + OH- (aq)
33 Hydroxyl Group in Molecules The –OH group in a molecule can be acidic or amphotericAs the number of oxygens that are bonded around the atom with the –OH group increases, so does the acidity of the compound.Oxygens pull electron density away from the hydrogen, making it appear more positive (and attractive to water and other bases)
35 Acids Neutralize Bases HCl + NaOH NaCl + H2ONeutralization reactions ALWAYS produce a salt and water.
36 Acids React with Carbonates 2HC2H3O2 + Na2CO32 NaC2H3O2 + H2O + CO2
37 Neutralization Reactions The reaction of hydromium and hydroxide ions to form water moleculesSteps:Dissociation of a base in waterAcid donates a proton to waterComplete ionic equationNet ionic equation (no spectator ions)
39 Products of Neutralization HCl + NaOH NaCl + H2OH2SO4 + Ca(OH)2 CaSO H2OHNO3 + KOH KNO3 + H2OThe products of neutralization are always a ______ and _______.saltwater
40 Acid Rain SO3 (g) + H2O (l) → H2SO4 (aq) Formation of Acid Rain: SO2, SO3, CO2, NO, NO2Formation of Acid Rain:Nonmetallic oxides enter the atmosphere as a result of burning coal, auto exhaust and other forms of air pollution.Nonmetallic oxides in the air then combine with water to form oxyacids:SO3 (g) + H2O (l) → H2SO4 (aq)
41 Effects of Acid Rain on Marble (calcium carbonate) George Washington:BEFOREGeorge Washington:AFTERCaCO3 (s) + 2H3O+ (aq) → Ca+2 (aq) + CO2 (g) + 3H2O (l)