Chemicals needed: sodium bicarbonate, concentrated hydrochloric acid.
1. Accurately weigh an empty, dry evaporating dish, and record its mass in blanks (b) and (e) in
the table below.
2. Add to the dish about 5 g of NaHCO
and weigh again. Record the mass in blank (a) in the
3. Add 5 to 6 mL of distilled water to the dish to wet the bicarbonate. Cover the dish with a
4. Move the watch glass aside slightly and add, in small portions, about 6 mL of concentrated
hydrochloric acid from a 10 mL graduated cylinder. These small portions of acid should be
added so that the acid runs down the inside wall of the evaporating dish. After the addition
of 6 mL of acid, continue adding acid only as long as CO
continues to be evolved.
5. Remove the watch glass and evaporate to dryness over a water bath (the evaporating dish is
placed on top of a beaker containing boiling water).
6. Next, heat the dish on wire gauze with the burner for about 3 minutes. Allow the dish to cool
and weigh accurately. Again, heat the dish, cool, and weigh. Continue heating and weighing
until the dish reaches constant mass. Record this constant mass in blank (d) in the table
(a) Mass of dish and NaHCO
(b) Mass of empty dish
(c) Mass of NaHCO
(d) Mass of dish and residue
(e) Mass of empty dish (b)
(f) Mass of NaCl residue [(d)–(e)]
7. In the reaction studied, what reactant was present in limiting quantity?
1. Calculate the theoretical yield of NaCl.
58.44 g NaCl
_________ g NaHCO
84.01 g NaHCO
2. Calculate the percentage yield of NaCl.
Actual yield × 100