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.
The reaction between solid chromium(III) oxide and solid carbon produced solid chromium and carbon dioxide gas. The equation for this reaction is: 2 CrâOâ(s) + 3 C(s) â 4 Cr(s) + 3 COâ(g) Solid iron reacts with aqueous hydrochloric acid to form aqueous iron(III) chloride and hydrogen gas. The equation for this reaction is: