Assigned problems _8, answers - Chemistry 2080 Spring 2011...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chemistry 2080 Spring 2011 Problem Set #8 - due date: Friday April 8th at 2 pm Name:________________ Lab TA Name:__________________ Lab Day/Time:______________________ 1) (a) Calculate the pH of a 1.3x10 -7 M solution of benzoic acid at 25°C. (The pKa of benzoic acid is 4.19 at 25°C. You may have to take into account the autoionization of water). (b) What is the percent ionization of the benzoic acid in this 1.3x10 -7 M solution at 25°C? We will use the abbreviation BzOH for benzoic acid, and BzO for the benzoate anion. The relevant chemical equation is: BzOH + H 2 O BzO + H 3 O + We have: K a = [BzO ][H 3 O + ] / [BzOH] = 10 -4.19 = 6.46 x 10 -5 . . . . . . . . . . . . . . . (1) Material balance: [BzOH total ] = [BzO ] + [BzOH] = 1.3 x 10 –7 M . . . . . . . . (2) We also have: K w = [H 3 O + ][OH ] = 1.00 x 10 –14 (at 25°C) . . . . . . . . . . . . (3) and the requirement of electroneutrality: [H 3 O + ] = [OH ] + [BzO ] . . . . . . . (4) So we have 4 equations in the 4 unknowns:
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 2

Assigned problems _8, answers - Chemistry 2080 Spring 2011...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online