CHEM 1120 1st Edition Lecture 13Outline of Last Lecture I. Bronsted-Lowry Acids and BasesII. Autoionization of WaterIII.pH ScaleOutline of Current Lecture I. Strong/Weak Acids and BasesII. Solving Quadratic Equilibrium EquationsIII. Polyprotic AcidsCurrent LectureI. Keep in mind that water can be an acid.In an acidic solution, [H+] >> [OH-] In a basic solution, [OH-] >> [H+]In a neutral solution, [H+] = [OH-]Strong Acids:HCl, H2SO4, HBr, HI, HNO3, HClO3, HClO4These are by definition strong electrolytes and exist totally ionized in aqueous solutionsFor monoprotic strong acids, [H3O+] = acidStrong Bases: Soluble hydroxides; alkali metals and heavier alkali earth metal hydroxides (Ca2+, Sr2+, and Ba2+)These also dissociate completely in aqueous solutionsThese 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.Most acids are weak acids, so memorizing the strong acids would benefit the mostKa is a measure of acid strength; the smaller the Ka the weaker the acid and vice versaFor all the strong acids, the Ka is greater than 1Use ICE tables and approximations to simplify problemsDon’t confuse strength, quantity, and concentrationStrength=strong—>weak, Quantity=much—>little, Concentration=concentrated—>diluteFor a generalized acid dissociation,and the equilibrium expression would be,Example: Calculate the concentrations of HNO2, H+, and NO2- in 0.2 M HNO2 II. How do we solve the previous algebraic equation?Option 1 is use a graphing calculator, but this is not allowed on the test.Option 2 is use the quadratic formula.Option 3 is the approximation method.We assume that x is negligible compared to the other concentrations, so therefore 0.2-x is equal to 0.2. In order to test the validity of the approximation, we use the 5% test. You would place “x” over the concentration (0.2) and multiply by 100. If this ends up being under 5% then it passes and we can use it. III. Polyprotic acids contain more than one mole of ionizable hydronium ions per mole of acid. An example of this is oxalic acid.Example: Calculate the concentrations of all the species in 0.2 M H2SO4.Ka=1.3 X 10^-2 Kb= 6.3 X
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