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.
5. Solutions of sodium sulfide and nickel (II) sulfate are mixed. Na 2 S(aq) + NiSO 4 (aq) â Na 2 SO 4 (aq) + NiS(s) Nickel (II) sulfide is the precipitate. 6. Solutions of ammonium sulfate and barium chloride are mixed. (NH 4) 2 SO 4 (aq) + BaCl 2 (aq) â BaSO 4 (s) + 2NH 4 Cl(aq) Barium sulfate is the precipitate.7.Na 2 S(aq) + ZnSO 4 (aq) â Na 2 SO 4 (aq) + ZnS(s) Zinc (II) sulfide is the precipitate.8.hem 1020 Precipitation reactions worksheet For each of the following combinations of reactants, do the following: â¢ Predict possible products with phase labels â¢ Write the balanced chemical equation. If no visible reaction occurs, write NR. If a precipitate forms, give the formula and name of the precipitate.