'Strongness' entry for pKa function?

User b85e2e3247

13-06-2011 22:13:40

How does one know what to enter for the 'strongness' pKa function? What scale is this on? Is this in reference to something?




ChemAxon bd13b5bd77

14-06-2011 08:52:42

Hi Jozsi,

could you please help me interpretting the strongness value in pKa?




User 851ac690a0

14-06-2011 09:18:58


Ok, but where was this expression found? :   "...strongness pKa function..."


User b85e2e3247

14-06-2011 15:37:31

This is one of the JChem for excel built in functions, it asks for 2 inputs (Molecule, Strongness), and I am confused about what to input for this strongness value.

ChemAxon bd13b5bd77

14-06-2011 15:39:51

JchemExcel just exposes the standard calculations plugin, so the standard CXN functions.

User 851ac690a0

14-06-2011 17:09:23


Ok;  I attached a screenshoot about the  "strongness index" expression. I could  explain its  purpose in this manner: 

The calculated pKa values of a molecule are shorted according to their strength and in this way an ordered list (vector) of pKa values will be avalable for  postprocessing.   The "Strongness index" refers to one of the index  in this orderd vector.

The first  element  of  this vector  is the strongest  acidic or basic pKa value.  Vector indexing start with "0". The last element of this vector is the weakest acidic or basic pKa value.


User 7c177bab3b

29-06-2011 15:40:28


It looks like the vector actually starts at index 1? Using zero returns a #VALUE! error.

Is there a way to determine the length of this vector should there be mulitple pKa values?



ChemAxon 0e37943a96

29-06-2011 16:29:31

Hi Stephen,

at the moment not. This is available at calculation time in code, but it would be hard to decide where to display it.

What you could do now is to simply display the various values for the strongness indexes into multiple columns and have #value displayed for invalid indexes.

It would be possible later to create an explicit function which would return the length of that vector.

Best regards,