1. [HAH] + :AH:A - The default red & blue coloring schema related with the next ionization steps. The default red & blue coloring schema does not depend on which ionic form of a molecule is submitted to the pK a calculation. The next three species have the same pK a value and the same color. Calculated pK a of the neutral, protonated and the deprotonated forms of ammonia according to the default red&blue coloring schema [HAH] + :AH pK a1 :AH :A - pK a2 +H + -H +

2. The non-default red & blue coloring schema depends on the submitted molecule [HAH] + pK a1 :AH:A - pK a2 :A - :AH pK a2 pK a1 [HAH] + Color-schema of ions is different from the default one. Color-schema of the neutral form :AH is the same than the default one. :AH :A - [HAH] + pK a1 pK a2 Calculated pK a of the neutral, protonated and the deprotonated forms of ammonia according to the non-default red&blue coloring schema -H + +H + -H + +H + -H + +H +

3. Differences between the default and the non-default red & blue coloring schema The non-default R&B schema refers exactly to the submitted molecule. Blue color assigned to the acid dissociation constant between the submitted base and its conjugated acid. Red color assigned to the acid dissociation constant between the submitted acid and its conjugated base. The default R&B schema always refers to the neutral reference state of the submitted molecule. Blue color assigned to the acid dissociation constant between the neutral base and its conjugated acid. Red color assigned to the acid dissociation constant between the neutral acid and its conjugated base.

4. Setting of the default and the non-default coloring schema on the pK a options panel Default setting Non-default setting