Explain how to prepare 1L of a buffer at pH 7.4 using 1M hypochlorous acid (Ka = 3.5 x 10-8) and a 1 M NaOH solution. Indicate the volume of hypochlorous acid and sodium hydroxide to use.
pH = pKa + log ([A-]/[HA])
Ka= [H+][A-]/[HA]
Molarity = moles/L
moles = g/molecular weight
pka=-log(3.5 x 10^-8)=7.46
pH=pKa+ log ([A-]/[HA]),
solve for [A-]/[HJA]
10^(pH-pKa)=[A-]/[HJA]=0.879
1-0.879=0.121=[A-]
Add 121mL of NaOH solution to a volumetric flask, and add HClO to the 1,000mL mark of a 1,000mL volumetric flask.