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Wednesday, November 8, 2017

Quantifying Hydrogen Bond Not

If we have greater confidence, with ice at a density of 916.7kgm3,

vboomice=3.4354916.710=314.92ms1

Tice=314.92218.0152810338.3144=71.63K

This is ice melting had it not been hydrogen bonded to 4 other molecules.  We are off by,

ΔT=273.1571.63=201.52K

This energy load is shared by 4 hydrogen bonds, so per hydrogen bond in ice (OH) contributes,

ΔTH,ice=50.38K per mole

This is non-sense because we are not sharing energy here.

If we propose that water molecules clusters in ice and effectively nice molecules move as a free particle with an increased molecular mass by nice times, and given that ice melts at 273.15K.

Tice=314.922nice18.0152810338.3144=273.15K

nice=3.8

which is much lower than when each molecule is hydrogen bonded to 4 other molecules making an expected n=5.  However, if ice melting is a surface phenomenon and does not occurs through out the solid, then on the surface, the top most layer of molecules has one less neighbor molecule.  This makes three hydrogen bonded neighbors and a expected cluster size of n=4.

With water at 100oC of a density 958.4kgm3,

vboomwater=3.4354958.410=329.25ms1

Twater=329.25218.0152810338.3144=78.30K

By a similar argument for a cluster of water molecules at 100oC, n100,

Twater=329.252n10018.0152810338.3144=373.15K

n100=4.76

which is higher than the expected n=4.4.

Kinetic theory for ideal gas does not apply to water at 100oC and ice at 0oC.  End of this issue.

Goodnight.