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).

Trial 1 Trial 2MEF & NH4OH ____0.01__ g _________ gMEF _________ g _________ gMNH4OH _________ g _________ gNH4OH (100 ml buret)

Vf ____0.1__ mL ________ mLVi _________ mL ________ mL

Actual V used _________ mL ________ mLHCl (50 ml buret)

Vf ____0.01__ mL ________ mLVi _________ mL ________ mL

Actual V used _________ mL ________ mL 

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)