Ammonia Titration Laboratory Activity   The Problem: Determine the molarity (M) and percent basicity (by mass) of ammonium hydroxide by acid/base titration. Information: 1. Ammonia in water forms NH4OH. (@ prep table) 2. Do not titrate ammonia samples of more than 10.0 ml at a time. 3. The burette at your lab station contains 1.2 M HCl. 4. Do no more than three trials.

Requirements and Goals of this Activity: 1. Work with your lab partner to summarize the procedure, which must be checked before you begin. 2. Record all data in a table. 3. Show all work for the calculations. 4. Assignment counts as a checked lab activity (vs formal lab)

Titration of Ammonium Hydroxide Solution   Procedure: ●Mass an empty 125 ml Erlenmeyer flask. ●Measure 10.0 ml of ammonia and add to flask. ●Mass the flask with ammonia. ●Add 2-3 drops of phenolphthalein. (turns pink) ●Titrate with 1.2 M HCL until pink color disappears (i.e. turns clear).

MEF & NH4OH ____0.01__ g _________ g MEF _________ g _________ g Trial 1 Trial 2 MEF & NH4OH ____0.01__ g _________ g MEF _________ g _________ g MNH4OH _________ g _________ g NH4OH (100 ml buret) Vf ____0.1__ mL ________ mL Vi _________ mL ________ mL Actual V used _________ mL ________ mL HCl (50 ml buret) Vf ____0.01__ mL ________ mL  

(.00750 L HCl) (1.2 mol / L) = .0090 moles HCl Calculations:   NH4OH + HCl  NH4Cl + H2O (6.75-8.25) (.00750 L HCl) (1.2 mol / L) = .0090 moles HCl   (.0090 mol HCl )(1 mol NH4OH) = .0090mol NH4OH (1 mol HCl) .0090 moles NH4OH = 0.9 M NH4OH .0100 L solution (0.81 – 0.99) (.0090 moles NH4OH) (35.0 g ) = 0.32 g NH4OH (1 mol NH4OH) (0.29 – 0.35) N = 14.0 5 H = 5.0 O = 16.0 35.0  0.32 g NH4OH x 100% = 3.2 % 9.98 g solution (2.9 – 3.5) (9.48-10.48)