CHEM 1120 Edition 1nd Lecture 14 Outline of Last Lecture I Equilibrium calculations a Percent ionization b Stepwise method II Weak bases and their relation to weak acids a Kb conjugate acid OH base b Categories of weak bases III Relationship between Ka and Kb a Kw Ka x Kb IV Acid Base properties of Salt solutions V Acid Base behavior and chemical structure a 3 factors Outline of Current Lecture I Factors affecting acid strength a Oxyacids II Hydrolysis of metal ions III Leveling effect IV Lewis Acids and Bases V Common ion effect 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 VI Buffered solutions a Composition b How does it work c Calculating pH d Current Lecture I II III IV V VI VII Factors affecting acid strength a For a series of oxyacids acidity increases with the number of oxygen b Resonance in the conjugate bases of carboxylic acids stabilizes the base and makes the conjugate acid more acidic Hydrolysis of metal ions a Water donates a proton end up with hydronium H30 b Not significant for alkali metal or alkaline earth metals Leveling effect a Water exerts a Leveling effect on any strong acid or base by reacting with it to form the products of water s autoionization b To rank strong acids in terms of relative strength we must dissolve them in a solvent that is a weaker base than water for example acetic acid Lewis Acids and Bases a Acid an electron pair acceptor i H BF3 CO2 ii Atoms with an empty valance orbital can be Lewis acids b Base an electron pair donor i OH NH3 NF3 ii Anything that could be a bronsted lowry base is a Lewis base iii Lewis bases can interact with things other than protons c A Lewis acid need not contain H ions a Lewis base need not contain OH ions Next Chapter Chapter 17 Common Ion Effect a Add a salt how does it affect the reaction b Common ion an ion common to two solutes c Common ion effect a shift in equilibrium cause by an addition of a common ion Buffered solutions a Buffered solutions buffers solution that resists pH change when small amounts of acid or base is added b Buffer composition a weak acid and its conjugate base or a weak base and its conjugate acid c How does a buffer solution work If a small amount of hydroxide is added to an equimolar solution of HF in NaF for example the HF reacts with the OH to make F and water i Similarly if acid is added the F reacts with it to form HF and water ii If base is added HX OH H20 Xiii If acid is added X H HX d Calculating pH of a buffer i Log H30 log Ka log HX X ii pH pKa log X HX iii When working with buffers do ICE tables in moles not molarity
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