STOICHIOCHEMISTRY LAB: DECOMPOSITION OF SODIUM BICARBONATE

Practice Questions

1 (a) Chemical equation for formation of iron (III) oxide.

(b) Mass of iron (III) oxide if 4.0 grams of iron are reacted.

(c) Mass of iron (III) oxide if 3.0 grams of oxygen reacted.

(d) Finding the limiting reagent if 4.0g of iron reacted with 3.0g of oxygen.

Moles of oxygen provided

Moles of Fe required

Moles of Fe provided

e) Mass of Iron (III) oxide theoretically formed

NB. All the Fe will be reacted but not all the oxygen will react.

(f) Percentage yield

2. (a) Equation

(b) Mass of nitric acid formed when 5 grams of nitrogen dioxide reacted.

(c) Mass of nitric acid formed when 5 grams of water reacted.

d) Calculation of limiting reagent

Moles of nitrogen dioxide required

Moles of nitrogen dioxide provided

(e) Mass of nitrogen monoxide formed when 5g of nitrogen dioxide reacted with 5 g of H₂O.

Lab Activity

Procedure

A clean evaporation dish was obtained and placed on a hot plate maintained at medium-high for 10 minutes. The evaporation dish was removed from the plate and placed on wire mesh to cool. The dish was weighed and recorded in the table. Masses of between 1.9g and 2.1g of Baking soda was added and the evaporating dish was heated for 25 minutes. The dish was removed from the plate and placed on the wire mesh to cool. The dish and its contents were weighed and recorded in the table. The evaporation dish was healed later for 10 minutes. The dish was removed and placed on the ire gauze to cool. The mass of the dish and the residue was recorded. The procedure was repeated until the mass recorded agreed within a margin of 0.01g. The apparatus were cleaned and stored properly.

Results

Table 1

Item	Mass
Empty evaporating dish	10.50g
Baking soda added	2.00g
Total dish and NaHCO3	12.50g
Dish& Contents after trial 1	10.20
Dish& Contents after trial 2	10.99
Dish& Contents after trial 3	10.98
Mass of residue after heating	0.48g

5. Equation

6(a) Mass of NaOH formed

b) % starting mass

1. Lowest mass

(10.98-10.50)g=0.48g

1. % mass
2. Most potential reaction

Reaction 2 is the most potential reaction since it occurs within a temperature range of 50^oC and 200^oC which is possible to achieve in a normal laboratory.