Chromium metal is found in ores as an oxide, Cr₂O₃. This ore can be converted to metallic Cr by the Goldschmidt process, Cr₂O₃(s) + 2 Al(s) → 2 Cr (ℓ) + Al₂O₃(s). Suppose that you have 4.5 tons of chromium (III) oxide. Describe how you would determine how much aluminum metal you would need to carry out this process. List any information you would have to look up.