phosphorous acid

phosphorous acid

formula | HP(O)(OH)_2 Hill formula | H_3O_3P name | phosphorous acid IUPAC name | dihydroxy-oxophosphonium alternate names | dihydroxy-keto-phosphonium | dihydroxy-oxo-phosphanium | dihydroxy-oxophosphanium | dihydroxy-oxo-phosphonium | phosphonic acid mass fractions | H (hydrogen) 3.69% | O (oxygen) 58.5% | P (phosphorus) 37.8%

Draw the Lewis structure of phosphorous acid. Start by drawing the overall structure of the molecule, ignoring potential double and triple bonds: Count the total valence electrons of the hydrogen (n_H, val = 1), oxygen (n_O, val = 6), and phosphorus (n_P, val = 5) atoms: 3 n_H, val + 3 n_O, val + n_P, val = 26 Calculate the number of electrons needed to completely fill the valence shells for hydrogen (n_H, full = 2), oxygen (n_O, full = 8), and phosphorus (n_P, full = 8): 3 n_H, full + 3 n_O, full + n_P, full = 38 Subtracting these two numbers shows that 38 - 26 = 12 bonding electrons are needed. Each bond has two electrons, so we expect that the above diagram has all the necessary bonds. However, to minimize formal charge oxygen wants 2 bonds. Identify the atom that wants additional bonds and the number of electrons remaining on each atom: In order to minimize their formal charge, atoms with large electronegativities can force atoms with smaller electronegativities on period 3 or higher to expand their valence shells. The electronegativities of the atoms are 2.19 (phosphorus), 2.20 (hydrogen), and 3.44 (oxygen). Because the electronegativity of phosphorus is smaller than the electronegativity of oxygen, expand the valence shell of phosphorus to 5 bonds. Therefore we add a total of 1 bond to the diagram: Answer: | |

3D structure

molar mass | 81.995 g/mol density | 1.651 g/cm^3

molar heat of fusion | 12.8 kJ/mol specific heat of fusion | 0.156 kJ/g (at STP)

CAS number | 13598-36-2 PubChem CID number | 3084169 PubChem SID number | 24852869 SMILES identifier | O[P+](=O)O InChI identifier | InChI=1/HO3P/c1-4(2)3/h(H-, 1, 2, 3)/p+1/fH2O3P/h1-2H/q+1 RTECS number | SZ6400000 MDL number | MFCD00137258