Lab 10 - Titration Curves Lab Typed Report copy

At the equivalence point, only NH 4 + and Cl - (NH 4 Cl) ions are present. NH 4 + is a conjugate acid of an weak base, NH 3 . So NH 4 + is relatively strong acid, and thus it will react with H 2 O to produce H 3 O + , making the solution acidic. Titration of a weak acid (CH 3 CO 2 H) with a strong base (NaOH) Fill-in the table below. (10 points) Show your computations clearly in your lab notebook. (4 pts) Value Initial volume of NaOH (initial buret reading), mL 1.95 mL Final volume of NaOH (final buret reading), mL 59.1 mL Drops, dp 172 Volume per drops, mL/dp 0.032 mL/dp Drops at equivalence point 1657 Drops at half-equivalence point 8.825 pH at half-equivalence point 4.475 pOH at half-equivalence point 9.524 Experimental pK a of acid 4.48 Percent error 6.04% Write an equation for the reaction that is taking place when the weak acid is titrated with the strong base. (3 pts) CH 3 COOH (aq) + NaOH (aq) → CH 3 COOHNa (aq) + H 2 O (l) Circle the major species present in the beaker (excluding water) at various points in the titration curve of acetic acid with sodium hydroxide. (8 pts) pH pH = 7 HC 2 H 3 O 2 HC 2 H 3 O 2 – H 3 O + OH – HC 2 H 3 O 2 HC 2 H 3 O 2 – H 3 O + OH – HC 2 H 3 O 2 HC 2 H 3 O 2 – H 3 O + OH – HC 2 H 3 O 2 HC 2 H 3 O 2 – H 3 O + OH – 3