Answer to Question #103183 in Chemistry for Uyobong

Question

Iron can be obtained by reacting the ore hematite (Fe2O3) with coke (C).
The latter is converted to CO2. As manager of a blast furnace you are told that you have
20.5 Mg (megagrams) of Fe2O3 and 2.84 Mg of coke on hand. (a) Which should you order
first—another shipment of iron ore or one of coke? (b) How many megagrams of iron can
you make with the materials you have?

Answer 1

The given reaction can be written as following:

Fe₂O₃ + 3C = 2Fe + 2CO

(a) To answer the first question, the limiting reagent should be determined. For the purpose, the number of moles of each reactant must be estimated:

n(Fe₂O₃) = m / Mr = 20.5 × 10⁶ g / 160 g/mol = 1.23 × 10⁵ mol

n(C) = m / Mr = 2.84 × 10⁶ g / 3 × 12 g/mol = 7.9 × 10⁴ mol

As carbon is a limiting reagent, more coke should be ordered.

(b) As carbon is a limiting reagent, 7.9 × 10⁴ mol of iron will be produced. As a result:

m(Fe) = n(Fe) × 2 × Mr (Fe) = 7.9 × 10⁴ mol × 2 × 56 g/mol = 8.85 × 10⁶ g = 8.85 megagrams

Answer: (a) coke should be ordered, (b) 8.85 megagrams