Chem 1120 1st Edition Lecture 12 Outline of Last Lecture I Detecting Radioactivity II Energy Changes in Nuclear Reactions III Fission and Fusion A Controlled vs Uncontrolled Fission IV Radiation in the Environment and Living Matter Outline of Current Lecture I Bronsted Lowry Acids and Bases II Autoionization of Water III pH Scale Current Lecture I Arrhenius Acids a substance that directly yields H ions when dissolved in water Arrhenius Bases a substance that directly yields OH ions when dissolved Bronsted Lowry Acid Base Defintion Acid proton donor any species which donates a H These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Base proton acceptor any species that accepts a H An acid base reaction can now be viewed from the standpoint of the reactants and the products An acid reactant will produce a base product and the two will constitute an acid base conjugate pair Conjugate acid base pair two species whose formulas differ by a single H HCN CN H2O H3O H2O OH Example Which of the following is the conjugate acid of each Which of the following is the conjugate base of each On the next page identify the Bronsted acids and bases on the left hand side and the conjugates on the right hand side Strong acids are strong electrolytes and therefore ionize completely in water Weak acids are weak electrolytes and do not ionize completely in water Some substances have negligible acidity in water The stronger an acid the weaker its conjugate base and the weaker an acid the stronger its conjugate base The same is true for a base and its conjugate acid Most common strong acids HCl HBr HI HClO3 HClO4 HNO3 H2SO4 Most common strong bases LiOH NaOH KOH group 1a metals with hydroxide Ca OH 2 Ba OH 2 Sr OH 2 heavy group 2a metals with hydroxide In any acid base reaction the equilibrium will favor the reaction that moves the proton to the stronger base II Water is very amphoteric so in pure water a few molecules act as acids and a few act as bases Water is a very weak electrolyte The ion product constant for water is Kw H OH 1 0 X 10 14 25 o Example The H concentration in the human stomach is about 0 3 M What is the OH concentration Solution Kw H OH 1 0 X 10 14 OH Kw H 1 0 X 10 14 0 3M 3 X 10 14 M III pH log10 H Example The pOH of a solution is 9 40 Calculate its H concentration Solution
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