University:
Bradley University
Course:
CHM 116 | General Chemistry II
Academic year:

2023
Views:

462

Pages:

3
Author:

Shyla Terry

PAL – Week 4 (Mon/Tu) #5 Acid base equilibrium, Part 2 (15.6-15.8) Name: Part A: Strong bases, Weak bases, Kb and pH 1) How many of the 6 important strong bases mentioned in your textbook can your PAL team remember? List their names and formulas below. Name Formula Name Formula 2) Complete the weak base table below by filling in each row with any missing formulas, ionization reactions, or base ionization constants, Kb. Formula Kb Ionization reaction + [CH3NH3 ][OH ] Kb = [CH3NH2] NH3 2CO3 (aq) + H2O(l) 1 HCO3 (aq) + OH (aq) 3) Calculate the pH of a 0.020 M solution of calcium hydroxide. -9 4) Calculate the pH of a 0.020 M solution of pyridine. Your book gives the Kb for pyridine = 1.7 x10 . 1 Part B: Acid-base properties of ions and salts 6) For each of the following salts, indicate whether it will produce an acidic, basic or neutral solution. If acidic or basic, write the hydrolysis (also called ionization) reaction in the space provided. Acid, base or neutral? Formula Ionization reaction a) LiC2H3O2 ___________________ _________________________________ b) NH4Br ___________________ _________________________________ ___________________ _________________________________ c) KClO4 d) Al(NO3)3___________________ _________________________________ 3+ hint for d): Al(NO3)3 is soluble in water. When dissolved, Al has water around (6 waters). ___________________ _________________________________ f) NH4NO2 ___________________ _________________________________ ___________________ _________________________________ e) NaOCl + hint for f): Ka for NH4 = 5.55 x 10 -10 - and Kb for NO2 = 2.17 x 10 -11 2 Part C: Calculating pH and pKb for basic ions 8) You walk into Chem 1B lab and notice that the labels have fallen off two bottles of base and are lying on the floor. One label reads “0.055 M KC2H3O2 solution” and the other label reads “0.055 M NaF solution”. You look up the pKb of F = 10.54 and the pKb of C2H3O2 = 9.25. a) You measure the pH of both solutions. The pH of the first bottle is 8.74. The pH of the second bottle is 8.10. Without doing any calculations, is the first bottle the KC2H3O2 solution of the NaF solution (hint: just look at the pKb values)? b) Now calculate the pH of the 0.055 M KC2H3O2 solution. Is this consistent with your answer above? Show all your work. (If you have time you can calculate the pH for the 0.055 M NaF solution.) 3