pKa H2CO3 is the cologarithm of the acid dissociation constant of carbonic acid. It is equal to 6.1. [HCO−3] is the molar concentration of bicarbonate in the blood plasma.
Tylenol may refer to:

Paracetamol (acetaminophen), a medication used to treat pain and fever
Tylenol (brand), an American brand of drugs containing paracetamol