An early development in chemistry was the verification of the Law of Definite Proportions. It was recognized that all binary compounds could be defined as a simple weight ratio between the constituent elements. The amount of an element could be expressed in the gram equivalent weight (GEW), the amount of an element that combines with 8.0000 grams of oxygen. Unlike atomic weight, the gram equivalent weight of an element can be found by chemical analysis of one of its binary compounds. Elemental sulfur reacts readily with metals to form binary metal sulfides, and was used in the following procedure to help a student determine the GEW of an unknown metal. The procedure consisted of four steps: Step 1 A porcelain crucible is cleaned with 6 M nitric acid and heated gently. After rinsing and drying, the crucible is heated with a Bunsen burner until the base has a deep red glow. The crucible is allowed to cool to room temperature and then weighed. The initial crucible weight is 23.0302 grams.
Step 2 A sample of the unknown metal is placed in the crucible and they are weighed together. The combined weight is 28.0423 grams
Step 3 Sulfur is then added, and the crucible with its contents are heated vigorously for 30 minutes. Excess sulfur is vaporized in this step.
Step 4 The crucible was allowed to cool to room temperature and then weighed. The combined crucible-metal sulfide weight is 34.6023 grams