# Chap 17_Aqueous Ionic Equilibrium.pdf - Aqueous Ionic...

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Aqueous IonicEquilibriumChapter 17Chemistry: Structure and Properties2ndeditionTro
Chapter OverviewWhat are buffers and how do they work?Henderson equationBuffer capacity and pH rangeAcid-Base titrations and titration curvesSparingly soluble salts and KspFactors affecting solubilityProblems based on these concepts
Problem 17.1a) Calculate the pH of a buffer solution that is4
b) Calculate the pH of a solution that contains
Problem 17.2A buffer is made by mixing 0.25 L of0.30 M Na2CO3and 0.30 L of 0.50 M NaHCO3Calculate the pH of this buffer.
Problem 17.3A buffer is made by adding 0.10 mol Aceticacid and 0.13 mol sodium acetate in waterto make 1.00 L of the solution.a) What is the pH of this buffer?b) Calculate the pH of the buffer after adding0.01 mol of solid NaOH. (Ignore volumechanges)Given Ka= 1.8×10-5
Problem 17.4A solution is 0.153 M in NaH2PO4and 0.159 M inNa2HPO4a)Calculate the pH of this solution.b)What will be the pH of the solution after 0.050mol of NaOH(s) is added to 1.00 L ofthe bufferin (a)c)What will be the pH of the solution after 0.050mol of HCl(g) is added to 1.00 L the buffer in (a)
Problem 17.5Which acid is the best choice to combine with thesodium salt of its conjugate base to make a solutionbuffered at pH 4.25? For the best choice, calculatethe ratio of the conjugate base to the acid required toattain the desired pH.chlorous acid (HClO2)pKa= 1.95formic acid (HCHO2)pKa= 3.74nitrous acid (HNO2)pKa= 3.34hypochlorous acid (HClO)pKa= 7.54
81.before adding any acid or base (initial pH is high or low)2.after adding acid or base- setup a reaction table- as base is added, it neutralizes H3O+- as acid is added, it neutralizes OH--calculate pH3.at the equivalence pt.-pH = 7 {always for SA/SB titration}4.beyond the equivalence pt.- setup a reaction table- acid or base will be in excess-calculate pHDetermining the pH
9PROBLEM (17.65)Consider the titration of a 35.0 mL sample of 0.175 M HBr with 0.200 M KOH.Determine each quantity.a.the initial pHb.the volume of added base required to reach the equivalence pointc.the pH at 10.0 mL of added based.the pH at the equivalence pointe.the pH after adding 5.0 mL of base beyond the equivalence pointFinding the pH during a SA/SB TitrationProblem 17.6
101.before adding any base (initial pH low)-calculate pHfrom WA dissociation2.after adding small amounts of SB- setup a reaction table (base added reacts completely w/ WA)- soln is now a buffer (account for total volume)-calculate pHusing He-Ha for each addition3.at the equivalence pt.- soln is no longer a buffer; WA has been converted to it conj base- find [conj base]= mols conj base @ equiv pt / total vol- set up ICE, solve for Kb, find x-calculate pH4.beyond the equivalence pt. (more addition of SB)- only strong base (OH-) is present- set up reaction table, find [OH-] = mols base/tot vol,calculate pHDetermining the pH
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