2Properties of Acids Sour taste Change the color of dyes known as acid-base indicators (turns litmus red)React with bases to produce a salt (ionic compound) and waterElectrolytes (aqueous solutions will conduct electric current)Can react with active metals to give off hydrogen gas (H2)
3Definitions of AcidsArrhenius (traditional): compound that contains hydrogen and ionizes in solution to form hydrogen ions (H+)Bronsted-Lowry: molecule or ion that is a proton (H+) donorLewis: atom or molecule that is an electron-pair acceptor
4Number of Protons in Acids Monoprotic acids can donate one H+ ion per moleculeExamples: HCl, HNO3, HBr, HClO4Diprotic acids can donate two H+ ions per moleculeExamples: H2SO4, H2SeTriprotic acids can donate three H+ ions per moleculeExample: H3PO4Polyprotic acids can donate more than one H+ ion per moleculeH2SO4 H+ + HSO4-HSO4- H+ + SO42-
5Hydronium IonHydrogen ion (H+) in an aqueous solution (H2O) becomes H3O+H3O+ is known as a hydronium ionThe terms hydrogen ion (H+), proton (p+), and hydronium ion (H3O+) are used interchangeably
6Naming Acids (Review) Binary Acids contain two elements (a cation, H+, and a monatomic anion)hydro______ic acidOxyacidscontains more than two elements (H, O, and3rd element)(a cation, H+, and a polyatomic anion with O)________ic acid (-ate ion goes with –ic ending)________ous acid (-ite ion goes with –ous ending)
7Oxyacid Naming Series per______ic acid most oxygen’s ______ic acid goes with –ate anion______ous acid goes with –ite anionhypo______ous acid least oxygen’s
8Properties of Bases Bitter taste Change the color of dyes known as acid-base indicators (turns litmus blue)React with acids to produce a salt (ionic compound) and waterElectrolytes (aqueous solutions will conduct electric current)Feel slippery to the skinBasic substances are referred to being “alkaline."
9Definitions of BasesArrhenius (traditional): compound that contains hydroxide and dissociates in solution to form hydroxide ions (OH-)Bronsted-Lowry: molecule or ion that is a proton (H+) acceptorLewis: atom or molecule that is an electron-pair donor
10Naming Bases (Review) Name as ionic compound Cation named first, anion named secondPotassium Chloride KClAll transition metals and Pb and Sn need Roman numerals to denote their charge. (Zn, Ag, and Cd don’t need Roman numerals.)Change ending of all nonmetals to –ide to name their monatomic anion.Polyatomic ions must be memorized! Review them if you have forgotten.
12Neutralization Acid + Base Ionic Compound + H2O The ionic compound formed from the reaction of an acid and a base is known as a salt. It is formed from the cation of the base and the anion of the acid.The cation from the acid (H+) and the anion from the base (OH-) form the waterHydrolysis: reaction between water and ions of a dissolved salt; causes water to dissociate into H+ and OH- ions
13Write balanced equations: barium hydroxide solution mixed with phosphoric acidaqueous sodium hydroxide neutralized with hydrochloric acidaluminum hydroxide solution mixed with chloric acidsulfuric acid reacted with aqueous magnesium hydroxide
15Info for Hydrolysis Worksheet strong acids (ionize 100% in solution):HClO4, HNO3, H2SO4, HI, HBr, HClstrong bases (ionize 100% in solution):Hydroxides of Groups 1 and 2 on Periodic TableIf they’re not strong, we assume they are weak!
16Bronsted-Lowry Conjugate Acid-Base Pairs Remember, B-L Acid: H+ donorB-L Base: H+ acceptorWhen an acid is dissolved in water, the acid (HA) donates a proton to water to form a new acid (conjugate acid) and a new base (conjugate base)HA (aq) + H2O (l) H3O+ (aq) + A- (aq)acid base conjugate acid conjugate baseH+H+
17Bronsted-Lowry Acid Conjugate Base HAHClHNO3H2SO4HSO4-H3O+H2OA-Cl-NO3-HSO4-SO4-2H2OOH-
18A few more items:Amphoteric: any species that reacts as either an acid or a basestrong acids have weak conjugate basesweak acids have strong conjugate basesstrong acids (ionize 100% in solution):HClO4, HNO3, H2SO4, HI, HBr, HClstrong bases (ionize 100% in solution):Hydroxides of Groups 1 and 2 on Periodic Table
19pH notes The pH scale ranges from 0 to 14. Any substance with a pH below 7 is classified as an acidAny substance with a pH above 7 is classified as a base.Substances with a pH of 7 are said to be neutral.(Pure water has a pH of 7.)__________________________________________________________________________| | | | | | | | | | | | | | |strong acid weak acid neutral weak base strong base
22TitrationTitration is the method used to determine the concentration of a solution (usually an acid or base).A solution of known concentration (the standard) is added to a measured amount of the solution of unknown concentration until an indicator signals the endpoint.The endpoint occurs when equivalent amounts of H+ and OH- have reacted in a titration, thus neutralizing the resultant solution.
23IndicatorsAcid-base indicators are dyes used in titrations whose colors are sensitive to changes in pH, or hydronium ion concentration.There are many indicators, each indicative of a different pH range. For most titrations, a neutralization reaction is desired.For a strong acid and strong base, the chosen indicator will change near the neutral point at a pH of 7.Examples: phenolphthalein (changes from clear in acid to pink in base) and bromothymol blue (changes from yellow in acid to blue in base)
24Sample Titration 50. mL of 0.1 M HCl when titrated with 0.1 M NaOH should take just over 50. mL to cause a color changebecause it is a monoprotic strong acid being neutralized by a group I hydroxide strong base.(For this titration, we would choose an indicator that changed color at a pH of 7 or neutral to indicate that the acid had been fully neutralized by the added base.)0.1 M H2SO4 substituted in the above problem would have a different effect since the H+ ion concentration would change for a diprotic acid
25Titration Equation MaVa = MbVb nbMaVa = MbVbna In titrations between acids and bases, neutralization is required so the [H+] = [OH-]In order to take this into account, our equation becomesnbMaVa = MbVbna# of H+ ions in baseMolarity of acidvolume of acidMolarity of basevolumeof base# of OH- ions in acid
26Functions as an Base or Acid AmphotericFunctions as an Base or Acid