Early wheels were simple wooden disks with a hole for the axle. In the early Roman empire, most horse-carts used a design featuring two chords across the wheel. The spoked wheel was invented much more recently, and allowed the construction of lighter and swifter vehicles.
Chromium(III) sulfide. Chromium(III) Sulfide is the inorganic compound with the formula Cr2S3. It is a brown-black solid. Chromium sulfides are usually nonstoichiometric compounds, with formulas ranging from CrS to Cr0.67S (corresponding to Cr2S3). Preparation.
Pyrrhotite, which is chemically called. iron sulfide, has the ideal formula FeS (Fe = iron, S = sulfur). This formula means that in. ANY AMOUNT of pyrrhotite, the ratio of iron to sulfur will be 1:1. molecules of iron sulfide). physical properties from the elemental iron and sulfur out of which it was formed. of used chemicals should follow the protocol developed by the school.