This document describes the process and calculations for determining the molar mass and ionization constant of a weak monoprotic acid. Two trials were conducted where the pH and volume of an acetic acid solution was measured before and after titration with a standardized NaOH solution. The moles of acetic acid and NaOH were calculated from the titration data. This was used to calculate the molar concentration, molar mass, and ionization constant of acetic acid.

1. Determination of the Molar Mass and lonization Constant of a Weak Monoprotic Acid Name
Date -section Locker _ Instru Average pH value Calculate the th (Note. In this s Data and
Calculations 1. Measurement of pH and titration of acetic acid solution Concentration of
standardized NaOH titrant Mass concentration of acetic acidgn mol/L 3. The ma Concentr Mass
co Trial 1 Trial 2 3-12 Measured pH of the acetic acid solution Mass of acetic acid solution taken
for titration 3002 Initial buret reading of NaOH titrant Final buret reading of NaOH titrant Net
volume of NaOH g 30-5 Mas Ini Fl 3.3 mlm 13.0 ml 13.m 325 mmol Millimoles of NaoH to end
point of tration 32 mmol Millimoles of acetic acid in sample Molar concentration of acetic acid
solution mol/L Calculated molar mass of acetic acid 5DO mmol 0 mmol mol/L g/mol g/mol
Calculation of the ionization constant for acetic acid from the measured pH of the samples.
(Average the pH and molar concentration values for the samples of acetic acid you tita average
values in the calculation of the ionization constant
Solution
Trial 1
Molar concentration = moles of acetic acid / volume of solution
= 500 mmol / 13.0 mL
= 38.46 mmol/mL
= 38.46 mol/L
Molar mass = mass/moles
= 30.02 g / (500 mmol x 10^-3 mol/mmol)
= 60.04 g/mol
Trial 2
Molar concentration = moles of acetic acid / volume of solution
= 508 mmol / 13.1 mL

2. = 38.78 mmol/mL
= 38.78 mol/L
Molar mass = mass/moles
= 30.5 g / (508 mmol x 10^-3 mol/mmol)
= 60.039 g/mol
= 60.04 g/mol