Step 1
The reaction provided must be written as follows:
Fe2O3 (s) + 3 CO (g) => 3 CO2 (g) + 2 Fe (s) (completed and balanced)
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Step 2
Information provided:
The limiting reactant CO and the excess reactant Fe2O3
209.7 g needs to be produced
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Information needed:
The molar mass of Fe = 55.85 g/mol
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Step 3
By stoichiometry
Procedure:
Fe2O3 (s) + 3 CO (g) => 3 CO2 (g) + 2 Fe (s)
3 moles CO ----------- 2 x 55.85 g Fe
X ----------- 209.7 g Fe
X = 209.7 g Fe x 3 moles CO/ 2 x 55.85 g Fe
X = 5.632 moles
Answer: 5.632 moles of CO are needed