Due this week 4 11 4 10 Unit 21 HW 4 12 Unit 22 HW 4 13 4 16 4 14 Unit 23 HW Unit 20 HW Unit 21 AF Exam 2 grades will be posted ASAP ACS Study Guide Sale Over 200 with 600 problems Topics separated into first and second semester material Worked examples 30 cash or Venmo Bring your ID MEYR 247 Proceeds benefit the UMBC ACS Student Chapter Questions mvanstav umbc edu 3 4pm Pay pickup as follows 4 10 order 5 8 pickup 4 12 order 5 10 pickup 4 14 order 5 12 pickup 10am 11am 11am noon 11am noon Noon 1pm Noon 1pm Noon 1pm 2 3pm 2 3pm 3 4pm M 4 3 M 4 10 W 4 12 F 4 14 M 4 17 W 4 19 F 4 21 M 4 24 27P R W 4 26 F 4 28 M 5 1 W 5 3 5 5 F 20 14 3 and 14 5 Determining Ka Kb pKa and pKb 21 14 3 22 14 3 23 14 4 24 14 4 25 14 6 26 14 6 Relative Strengths of Acids and Bases Acid Base Equilibrium Calculations Salts Predicting pH Salts Calculations Buffer Identification Buffer Calculations Solution Identification Titrations Precipitation and Dissolution 27 14 7 28 15 1 Exam Review Exam Review EXAM 3 Units 20 28 Unit 21 Relative Strengths of Acids and Bases For a list of weak acids As the magnitude of Ka increases pKa decreases the strength of the weak acid increases Why There is more H3O in solution pH decreases for solutions at the same concentration For a list of weak bases As the magnitude of Kb increases pKb decreases the strength of the weak base increases Why There is more OH in solution pH increases for solutions at the same concentration Every weak acid has a Ka value The conjugate base has a Kb value Kw Ka Kb The larger the Ka of the acid the smaller the Kb of the conjugate base The stronger the weak acid the weaker its conjugate base Every weak acid has a pKa value The conjugate base has a pKb value pKw pKa pKb The larger the pKa of the acid the smaller the pKb of the conjugate base The stronger the weak acid the weaker its conjugate base Every weak base has a Kb value The conjugate acid has a Ka value Kw Ka Kb The larger the Kb of the base the smaller the Ka of the conjugate acid The stronger the weak base the weaker its conjugate acid Every weak base has a pKb value The conjugate acid has a pKa value pKw pKa pKb The larger the pKb of the base the smaller the pKa of the conjugate acid The stronger the weak base the weaker its conjugate acid Molecular Structure and Acid Base Strength Binary hydrogen compounds Ternary acids and bases oxoacids Which acid HA or HX has the higher pH Ka for HA 25 C 1 5 x 10 5 Ka for HX 25 C 1 9 x 10 8 1 5 10 5 1 9 10 8 The higher pH comes from the weaker acid As Ka increases acid strength increases 12 Which of the following will have the strongest conjugate acid C6H5NH2 Kb 4 2 x 10 10 NH2OH Kb 6 6 x 10 9 CH3 3N Kb 7 4 x 10 5 NH3 Kb 1 8 x 10 5 Kw Ka Kb The larger the Ka of the acid the smaller the Kb of the conjugate base The stronger the weak acid the weaker its conjugate base For a group of weak bases with the same concentration as the value of pKb increases the pH will decrease As pKb goes up the corresponding Kb goes down A smaller Kb corresponds to a weaker base i e OH decreases Less OH means it is less basic pOH goes up pH goes down Which pKb value corresponds to a conjugate acid base pair with the strongest acid 12 11 9 58 7 84 3 29 The strongest acid in a list has the largest Ka and therefore the smallest pKa Its conjugate base pair would have the largest pKb in the list Which of the following is the strongest acid HBrO4 HBrO3 HBrO2 HBrO The highest the oxidation number of the central atom in a series of oxoacids the more acidic it is 16 At the same concentration and temperature which pH corresponds to the weak base with the highest pKb 7 11 8 02 9 16 10 5 The higher the pKb the lower the Kb and the weaker the base The weakest base will have the lowest pH For the binary acids HI HBr HCl HF Kw Ka Kb For the conjugate bases I Br Cl F For a group of weak acids with the same concentration as the value of pKa increases the basicity will increase As pKa goes up the corresponding Ka goes down A smaller Ka corresponds to a weaker acid i e H3O decreases Less H3O means it is less acidic and more basic