chem question?

Question

Hypophosphorous acid, H3PO2, has the structure (HO)PH2O, in which two atoms are bonded to an O atom. For each bond to an H atom, decide whether it is polar or nonpolar. Assume that only polar-bonded H atoms are acidic. Write the balanced equation for the complete neutralization of hypophosphorous acid with sodium hydroxide. A 200.0-mL sample of H3PO2 requires 22.50 mL of 0.1250M NaOH for the complete neutralization. What is the molarity?

Answer 1

H3PO2 is
......H
H - P =O
......OH
Moles NaOH = 22.50 x 0.1250 / 1000 = 0.002813
Moles H3PO2 = 0.002813
M = 0.002813/ 0.200 L = 0.001407

Answer 2

H isbonded to O or P. The electronegativities of both H and P are 2.1. Because there is no difference, the P-H bonds are nonpolar. The electronegativity of O is 3.5, so the O-H bond is polar.

Let H3PO2 be rewritten HPH2O2. Let NaOH solution be called NS. Let hypophosphorous acid solution be called PS.

HPH2O2 + NaOH ===> Na+ + PH2O2- + H2O

22.50mLNS/200.0mLPS x 0.1250molNaOH/1LNS x 1LNS/1000mLNS x 1molHPH2O2/1molNaOH x 1000mLPS/1LPS = 0.01406 mole/L, which is molarity

Answer 3

H in H-O-P is acidic, and is part of a very polar bond.

The other two H atoms are directly attached to P, which is much more similar to H in electronegativity, so these bonds are only weakly poler and for the purposes of this question you can assume they are non-polar.

So now you know how many acidic hydrogens there are in each molecule, and you are left with an ordinary acid-base titration problem.