Once there, on the left side, click on "Section 3: Physical Constants of Organic Compounds" (boiling point is a physical property). You can use either the PDF or Interactive Table and then scroll down to what you are looking for or do a search (even before you click on Section 3). The pressure corresponding to this boiling temp is 1 atm (760.0 mm Hg).
H3PO4 + NaOH --> NaH2PO4 + H2OThe equation to use to obtain the molarity of the acid (H3PO4), Ma, is:
Ma * Va = Mb * Vb (page 99 in manual)The second titration again starts with fresh unknown, so the first portion of NaOH added changes the H3PO4 to NaH2PO4. After this portion has been added, the solution is y + z molar in NaH2PO4. Further addition of base will neutralize not only the z molar NaH2PO4 originally present in the unknown but also the y molar salt formed from the y molar H3PO4 originally present, forming Na2HPO4 from both when the end-point is reached. The chemical reactions for the second titration are:
H3PO4 (y molar) + 2 NaOH --> Na2HPO4 + 2 H2O
NaH2PO4 (z molar) + NaOH --> Na2HPO4 + H2O
Thus, for the second end point: MBase * VBase = VSample * 2y + VSample * zThe equation to use to obtain the molarity of the salt (NaH2PO4), Ms, is:
(Va * 2Ma) + (Va * Ms) = Mb * Vb (page 100 in manual)