Calculate the pH at the equivalence point in titrating 0.100 M solutions of each
ID: 609987 • Letter: C
Question
Calculate the pH at the equivalence point in titrating 0.100 M solutions of each of the following with 8.010?2 M NaOH .
Calculate the pH at the equivalence point in titrating 0.100 M solutions of each of the following with 8.0½10?2 M NaOH . Part A hydrobromic acid ({ rm HBr}) Express your answer using two decimal places. Part B chlorous acid({ rm HClO_2}) Part C benzoic acid( rm C_{6}H_{5}COOH )Explanation / Answer
0.1M HClO2 x 1L = 0.1moles HClO2 0.1moles H+ + 0.08moles OH- --> 0.08moles H2O + 0.1moles H+ since there are no volumes in the problem, i'm assuming 1L for all solutions. 0.1moles HClO2 / 2L = 0.05M HClO2 Ka HClO2 = 0.011 0.011 = [H+][ClO2-] / [HClO2] 0.011 = x^2 / 0.05 - x 5.5x10^-4 - 0.011x = x^2 x^2 + 0.011x - 5.5x10^-4 = 0 x = [H+] = 0.0186M pH = 1.7 0.1M HC7H5O2 + 0.08M OH- again, this will leave you with 0.05M HC7H5O2 Ka HC7H5O2 = 6.3x10^-5 6.3x10^-5 = [H+][H7H5O2-] / [HC7H5O2] 6.3x10^-5 = x^2 / 0.05-x 3.15x10^-6 - 6.3x10^-5x = x^2 x^2 + 6.3x10^-5x - 3.15x10^-6 = 0 x = [H+] = 0.00178M pH = 2.75