Standardization of formaldehyde stock solution - Transfer a 25 mL
aliquot of a 0.1 M Na SO solution to a beaker and record the pH. Add a 25.0 mL aliquot 2 3
of the formaldehyde stock solution (Sec. 5.18.1) and record the pH. Titrate this mixture
back to the original pH using 0.1 N HCl. The formaldehyde concentration is calculated
using the following equation: