Question

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

Answers

Devron
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.

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