Water Properties

  • Extremely high mp and bp:

 

MW

m.p.

b.p.

Water

18

0°C

100°C

Methane

16

-183°C

-161°C

 

 

 

 

  • High Heat capacity: 18 cal/°C mol vs. 8 cal/°C mol for methane

  • High viscosity

  • Solid form is less dense than the liquid form at the same temperature (ice floats on water - very rare)

  • High dielectric constant (78.5 vs. 1.9 for hexane; 'blocks electric fields')

  • High surface tension.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Structural diagram of water molecule showing bond angles and lengths

public domain image via Wikipedia Creative Commons

 

 

Space-filling image of water molecule

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#-D image of H-bonding between space-filling images of water molecules

public domain image via Wikipedia Creative Commons

 

 

 

 

 

 

 

 

 

 

 Interaction Type
Example Average Strength, kcal/mol (kJ/mol) Range**
Charge-charge (ionic) -NH3+ Cl-   1/r
Charge-dipole -NH3+ClCH3   1/r2
Dipole-dipole ClCH3 ClCH3    1/r3
Dipole-induced dipole* CH4 ClCH3 0.1-0.2 (0.4-4)  1/r6
Dispersion*
(induced dipole-induced dipole)
CH4 CH4

0.1-0.2 (0.4-4)
1/r6
Hydrogen bond  two H-bonded water molecules 3-8 (12-30)  

 van der Waals repulsion
    1/r12

*van der Waals interactions, **from Zubay Biochemistry 3rd. (1993) Table 4.3, pg. 89.

 

 

 

 

 

 

 

 

 

 

 

artists image of micelle, liposome and lipid bilayer

public domain image via Wikipedia Creative Commons

 

 

 

 

 

 

 

 

 

 

 

 

Flattened image of the hydration of sodium ion

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© R A Paselk

Last modified 1 February 2010