Clinically, a blood pH of 7.4 is considered a normal value. If the pH of the blood is lower than 7.4, it is shown that the blood is acidic, that you have acidosis or a lack of bases. If the pH of the blood is above 7.4, it is said that the blood is alkaline, that you have an alkalosis or excess of base.
For calculating pH of blood, we will use next equation:
pH = -log c(H⁺)
pH = -log(4.0x10⁻⁸)
pH = 7.4