Question

A buffer is prepared by adding 18.0 g of sodium acetate (CH3COONa) to 490 mL of a 0.140 M acetic acid (CH3COOH) solution.

1) Determine the pH of the buffer.

2) Write the complete ionic equation for the reaction that occurs when a few drops of hydrochloric acid are added to the buffer.

(Express your answer as a chemical equation. Identify all of the phases in your answer.)

3) Write the complete ionic equation for the reaction that occurs when a few drops of sodium hydroxide solution are added to the buffer.

(Express your answer as a chemical equation. Identify all of the phases in your answer.)

Answer 1

= 0.2194 mole : # Sodium acetate and acelic acid buffer solution: © Molar mass of sodium acetate = 82.03 g mol 1. Amount of sodium acetate a 8200 (C Hz Crona) 18.09 82.03 gi moi [Cita Coona] = 0.2094 mol mol = 0.447 M Nisor 0.990 L [CH3 COOH] = 0.1404 Ka of CH3COOH = 1.8x10-5 is bka = -log ka = -10g (118 x10-5) = 9.74 & pH at the buffer solution we can calculate by using Henderson equation → pH = pka + log bata [CH3COONa] [<h3 солоні .- 4.74 + 10g (0:997) = 5.24 ÞH= 5.24 , pH of buffer solution = 5:24 • When a strong acid (Hell is added to this buffer, the conjugate base will react with t3o imr by the acid in solution in a neutrallisation reaction This reaction will produce water and acetic acid, which is a weak acid - As a result pH of the buffer solution will not change significantly by the addition of the .

Equation Hu (ag) + H20 (1) -> H307a2} + (aq) CHE COO(aq) + Hg of (aq) → CH3 C00H (aq) + H2000 (buffer) (added Hel). when few drops.at NaOH Solution are added to the buffer solution the acetic acid will react ceith Naoh and it will produce Citycoona (salty and water. Soy Salt is formed and aceed is reached Amount of salt and acial both differ slightly.ph change also not significant, slight pit change oscurs cae). I nol ! (aq) Equatton. CHCOOH" + NaOHA (Bufter). (added) lity coona + H200. - Palt Salt dette

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