Describe how you will make 50.0mL of an acetic acid/sodium acetate buffer of pH

Question

Describe how you will make 50.0mL of an acetic acid/sodium acetate buffer of pH 4.8. You will have available 0.50M solutions of acetic acid, sodium acetate, HCl and NaOH available for your use. ALSO WRITE THE INTENDED PROCEDURE. PLEASE SHOW ALL WORK AND EQUATIONS

Explanation / Answer

pKa of Acetic Acid = 4.76........Prepare a buffer of acetic acid/sodium acetate.........pH = pKa + log (S/A) => 4.8 = 4.76 + log (S/A) ......=> (S/A) = 1.0965.......(S = Salt......A = Acid)...... [S] = 0.25 (0.5/2....since it gets diluted by acetic acid as well) .......=> [A] = 0.25 / 1.0965 = 0.228 M............ Moles of Acetic Acid actually present = 0.5 x 0.025 = 0.0125........Moles we want = 0.228 x 0.05 = 0.0114.......Therefore moles to be neutralized = 0.0125 - 0.0114 = 0.0011 moles.......We neutralize this by adding NaOH........V x 0.5 = 0.0011......=> V = 0.0022 Liters = 2.2 ml.............Therefore we add 24 ml Acetic Acid.......24 ml sodium acetate and 2 ml of NaOH to make desired pH

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