Answer:
The molar mass of the acid is 167.5 g/mol
Explanation:
A 0.4021-g sample of a purified organic acid was dissolved in water and titrated potentiometrically. A plot of the data revealed a single end point after 19.31 mL of 0.1243 M NaOH had been introduced. Calculate the molecular mass of the acid.
Step 1: Data given
Mass of the sample of a purified organic acid = 0.4021 grams
Molarity = 0.1243 M
Volume needed to reach the end point = 19.1 mL = 0.01931 L
Step 2: Calculate the number of moles NaOH
Moles NaOH = molarity NaOH * volume
Moles NaOH = 0.1243 M * 0.01931 L
Moles NaOH = 0.00240 moles
Step 3: Calculate moles of the acid
We'll need 0.00240 moles of acid to neutralize 0.00240 moles of NaOH ( it's a single end point)
Moles acid = 0.00240 moles
Step 4: Calculate molar mass of the acid
Molar mass = mass / moles
Molar mass = 0.4021 grams / 0.00240 moles
Molar mass = 167.5 g/mol
The molar mass of the acid is 167.5 g/mol
