Properties of acids I e Al Zn Fe not Cu Ag or Au Corrosive Sour taste React with active metals React with carbonates producing CO2 Marble chalk limestone baking soda Change color of vegetable dyes react with bases to form ionic salts Blue litmus turns red Properties of bases Alkaloids plant product that is alkaline Also known as alkalis Taste bitter Solutions feel slippery Change color of vegetable dyes Different color than acid Red litmus turns blue React with acids to form ionic salts Neutralization Structures of acids HCl HF Binary axis have acid hydrogenated attached to a nonmetal atom Oxy acids have acid hydrogens attached to an oxygen atom Carboxylic acids have COOH group HC2H3O2 H3C6H5O7 Only rst H in formula is acidic H2SO4 HNO3 Structures of bases NaOH Ca OH 2 Most ionic bases contain OH ions Some contain Ca3 2 ions CaCO3 NaHCO3 Molecular bases contain structures that react with H Mostly amine groups Visual indicators Chemicals that change color depending on solution s acidity basicity Many vegetable dyes are indicators Litmus Red in acid Blue in base Phenolphthalein Red in base Colorless in acid Arrhenius Theory Ionic substances dissociate in water Bases dissociate in water to produce OH ions and cations Acids ionize in water to produce H ions and anions Because molecular acids are not made of ions they cannot dissociate They must be pulled apart or ionized by the water In the formula ionizable H is normally written in front Arrhenius Acid Base reactions Acid and base form salt water Problems limited to acid base reactions in aqueous solutions Cannot explain some of the reactions that happen in solutions of acids and bases alike Bronsted Lowry Acid Base Theory Rede nes acids and bases based on what happens in a reaction Any reaction that involves H being transferred from one molecule to another is an acid base reaction regardless of whether it occurs in aqueous solution or if there is OH present Incorporates Arrhenius theory Species that provides H is an acid Species that accepts H is a base Bronsted theory vs Arrhenius In BL acid base reaction the acid molecule gives an H to the base molecule In Arrhenius reaction acid base salt water Hydronium Ion The H ions produced by the acid are so reactive they cannot exist in water Instead they react w water molecules to produce complex ions mainly hydronium ion H3O Any material that has H can potentially be a BL acid Bronsted Lowry Acids Are H donors Bronsted Lowry Bses Are H acceptors Amphoteric Substances BL acid base reactions Conjugate pairs Any material that has atoms with lone pairs can potentially be a BL base Because of the molecular structure often one atom in the molecule is more willing to accept H transfer than others When NH3 dissolves in water the NH3 aq is the base because NH3 accepts an H from H2O OH is formed Can act as either acid or base Have both a transferable Hand an atom w lone pair electrons Water acts as base accepting H from HCl Water acts as acid donating H to NH3 Allows reactions to be reversible H A B A H B The original base has an extra H after the reaction so it will act as an acid in reverse process And the original acid has a line pair after the reaction In BL acid base reaction the original base becomes an acid in the reverse reaction and the original acid becomes a base in the reverse process Each reactant and the product is becomes is called conjugate pair Example identify the BL acids and bases and their conjugated in the reaction Example write equations for reaction w water Example write equation Strong or weak Practically all the acid molecules ionize A strong acid is a strong electrolyte A strong base is a strong electrolyte Practically all the base molecules form Oh ions either through dissociation or reaction w water Weak acid is weak electrolyte Weak base is weak electrolyte Only small percentage of molecules ionize Stronger the acid the more willing it is to donate H Donate mostly all their H s 1 M HCl 1 M H 1 M H2SO4 2 M H Strong Acids Weak Acids Memorize list of strong and weak acids in book Donate small fraction of theirH s Increasing acidity corresponds with decreasing basicity for conjugate bases Strengths of Acids and Bases Strong acid weak attraction complete ionization Weak acid strong attraction partial ionization Commonly acid or base strength is measured H determining equilibrium constant of a substance s reaction w water The farther he equilibrium position lies toward products the stronger the acid or base General trends in acidity Stronger the acid weaker the conjugate base Higher oxidation number stronger oxyacid H2SO4 H2SO3 HNO3 HNO2 More oxygens stronger A cation is a stronger acid than a neutral molecule neutral stronger acid than ion H3O H2O Acid Ionization Constant Ka Acid strength measured by the size of the eq constant when reacts with H2O Hacienda H2O Acid H3O The eq constant for this rectiom is the acid ionization constant Ka Larger Ka stronger acid Autoionization of water Must be a few ions present Water is actually an extremely weak electrolyte About 2 out of every 1 billion molecules form ions through process called Autoionization All aqueous solutions contain both H3O andOH Concentrations are equal in water Kw H3O x OH constant 1 00 x 10 14 25 degrees C All aqueous solutions contain both H3O and OH ions Neutral solutions have equal amounts 1 00 x 10 7 Acidic solutions have more H3O Basic solutions have more OH Ion Product of Water Acidic and Basic Solutions Example calculate OH at 25 degrees C when the H3O 1 5 x 10 9 M and determine if the solution is acidic basic or neutral Measuring Acidity the pH scale Sig gs and logs pH log H3O pH 7 is acidic pH 7 is basic pH 7 is neutral H3O 10 pH When you take log of number digits before decimal point come from exponent on 10 and digits after decimal point come from decimal part of the number Log 2 0 x 10 6 log 10 6 log 2 0 6 0 3030303 The sig gs are the digits after the decimal point in the log 6 30 Example calculat pH at 25 degrees C when OH 1 3 x 10 2 M pOH Calculate pH when OH 1 3 x 10 2 M pK log OH OH 10 pOH pOH 7 basic pOH 7 acidic pOH 7 neutral pH pOH 14 Way of expressing strength of an acid or base pKa log Ka Ka 10 pKa PKb log Kb Kb 10 pKb The stronger the acid the smaller the pKa The stronger the base the smaller the pKb Larger Ka smaller pKa Because it is the log Larger Kb smaller pKb H3O and OH in strong acid or strong base solution There are two sources of H3O in an aqueous solution of a strong acid the