Supplemental Instruction 1060 Hixson-Lied Student Success Center 294-6624 www.si.iastate.edu Chemistry 178 Exam 2 Review Supplemental Instruction Iowa State University Leader: Alarm Cho Course: Chem 178 Instructor: John Verkade Date: Oct. 20, 2009 Concepts Chapter 16 – Acid-Base Equilibria Acids and Bases - Definitions: Bronsted-Lowry (protons) Arrhenius ([H+],[OH-]) Conjugate Acid, Base pairs Amphiprotic (i.e. Water) Relative Strengths of Acids - Strong Acid - Weak Acid - Negligible Acid - Equilibrium in Acid-Base Reaction Autoionization of Water - Amphoteric (i.e. water) - Ion Product Constant of water (Kw) The pH scale - - Pure water pH = 7 - Acidic pH >7 - Basic pH < 7 - - p{ } means = ? - pH + pOH = 14 Measuring pH – litmus paper, indicator, pH meter Strong Acids and Bases - Know the strong acid and base list - Strong acids and bases dissociate completely. - Weak Acids - Acid Dissociation Constant (Ka) - Relationship b/t the constants and - acid strengths - Calculating pH from Ka & visa versa - Calculating percent ionization Polyprotic Acids - Subsequent Ka’s for different protons released Weak Bases - Base Dissociation Constant (Kb) - Relationship b/t the constants and base strengths - Calculating pH of basic solution from Kb & visa versa Relationship between Ka and Kb - Ka × Kb = Kw - pKa + pKb = pKw = 14 Acid-Base properties of salt solutions - Effects of cations and anions on pH. (p.695-697 in txt bk) Factors affecting Acid strength - Polarity of bond - Bond strength - Stability of conjugate base Binary acid strengths - Across the row, down a column Oxyacid strengths - Proportional to the number of oxygens - When same number of oxygen and OH groups, then stronger with stronger electronegativity of central Y atom. Carboxylic Acid - Resonance structure Lewis Acids and Bases - Accept/Donate electron pairs - Hydrolysis of metal ions Chapter 17—Additional Aspects of Aqueous Equilibria Common Ion Effect - Ties into Le Chatlier’s Principle Buffered solutions - Definition- Henderson-Hasselbalch Equation (calculating pH of buffer) - pH Range, Buffer capacity - Addition of strong acid to buffers. - Addition of strong base to buffers. - Problem solving strategy—diagram from notes. Acid-Base Titrations - Understand the titration curve. It can serve as a flow chart when solving titration problems. - Strong acid-strong base - Weak acid-strong base - Weak base-strong acid - Titration curve and the strength of weak acids - Titration curve of polyprotic acids Solubility Equilibria - Solubility product - Solubility Factors that affect solubility - Common ion effect - pH - Complex ions - Amphoterism - Precipitate formation (Q vs. Ksp) - Selective precipitation of ions Know your demonstrations and equations! Also know how to do homework problems and all the quiz problems. If you want more detail in the subjects listed on the review sheet, please refer to the notes or the previous SI
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