WHAT IS PK2?

pK2 for H3PO4. Look in your text for k2 for H3PO4. My text, but it's an OLD OLD one lists k2 of 6.2E-8 and pK2 = 7.21.

DRBOB. It is the same in my reference as well, 6.23E-8 or pK2=7.21 at 25C.

PK2 refers to the second ionization constant of a weak acid. In this particular case, we are referring to the pK2 value of H3PO4, which is the formula for phosphoric acid. The pK2 value represents the negative logarithm of the second ionization constant.

To find the pK2 value for H3PO4, you can consult a reliable source of information such as a textbook or a reference book. In this case, the user mentions finding it in their old textbook which lists the k2 value as 6.2E-8 and the pK2 value as 7.21.

It is important to note that the pK2 value is temperature-dependent. The user also mentions that the same values are present in their reference source, confirming the consistency of the information.

So, PK2 refers to the second ionization constant of a weak acid, and in the case of H3PO4, the pK2 value is 7.21 at 25°C.