Question

If 11.8 mol of iron(iii) oxide and 22.2 mol of carbon react, how many moles of the excess reactant will remain after the reaction? 2 fe2o3(s) 3 c(s) → 4 fe (s) 3 co2(g)

(a) 1
(b) 3
(c) 5
(d) 7

Answer 1

The balanced reaction between iron(III) oxide and carbon shows that 11.8 moles of iron(III) oxide would require 17.7 moles of carbon to react fully. With 22.2 moles of carbon initially present, 4.5 moles of carbon would remain after the reaction. Therefore, the closest answer is 5 moles of excess carbon. Option C is correct.

Step-by-step explanation:

When determining how many moles of the excess reactant will remain after a reaction, we must consider the stoichiometry of the reaction. The balanced chemical reaction for the reduction of iron(III) oxide with carbon is:

2 Fe2O3(s) + 3 C(s) → 4 Fe(s) + 3 CO2(g)

According to the balanced equation, 1 mole of Fe2O3 reacts with 1.5 moles of carbon. Given that we have 11.8 moles of Fe2O3 and 22.2 moles of carbon, we set up the ratio:

11.8 mol Fe2O3 × (1.5 mol C / 1 mol Fe2O3) = 17.7 mol C

This calculation shows that 17.7 moles of carbon are required to react with 11.8 moles of Fe2O3. Since we started with 22.2 moles of carbon, we subtract the amount of carbon that reacted:

22.2 mol C - 17.7 mol C = 4.5 mol C

Therefore, after the reaction, 4.5 moles of carbon will be in excess. This means that option (c) 5 is the closest answer, as we typically round to the nearest whole number in stoichiometry problems when discussing amounts of substance.