2. Henderson-Hasselbalch equation lHCO3 pH=pKa+lg H2CO31 20 pKa+lg =61+ lg hco3/0.03×PCO2 6.1+lg24/1.2=74 6.1+13=74 pH7.35~7.452. Henderson-Hasselbalch Equation pH=pKa+lg [HCO3 - ] [H2CO3 ] =pKa+lg 20 1 = 6.1 +1.3 = 7.4 pH 7.35~7.45 = 6.1 + lg HCO3 - / 0.03 × PCO2 = 6.1 + lg 24 / 1.2 = 7.4