User guide

Heat of formation
Reported in KJ/mole, the heat of formation is the increase in enthalpy resulting from the formation of one mole of a sub-
stance from its constituent elements at constant pressure.
Henry’s law constant
A unitless value, Henry's Law Constant can be expressed as:
Where ‘p’ is the partial pressure of the solute in the gas above the solution, ‘c’ is the concentration of the solute and
‘k
H,pc
’ is a constant with the dimensions of pressure divided by concentration. The constant, known as the Henry's
law constant, depends on the solute, solvent, and temperature.
LogP
The partition coefficient is a ratio of concentrations of un-ionized compound between two solutions. To measure the
partition coefficient of ionizable solutes, the pH of the aqueous phase is adjusted so that the predominant form of the
compound is un-ionized. The logarithm of the ratio of the concentrations of the un-ionized solute in the solvents is
called LogP.
Normally, one of the solvents chosen is water; the second is hydrophobic, such as octanol.
The formula to calculate LogP is:
LogS
LogS determines the solubility of a substance, measured in mol/liter.
The aqueous solubility of a compound is known to significantly affect absorption and distribution characteristics of
that compound.
Note: LogS calculations are available only in Windows version of ChemBioDraw 13.0.
Melting point
Is the temperature at which a solid becomes a liquid at standard atmospheric pressure. At the melting point, the solid
and liquid phase exist in equilibrium. The formula to calculate melting point is:
ChemBioDraw 13.0
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