Answer:
- <u><em>O₂ is the limiting reactant.</em></u>
Explanation:
To find which of the <em>available reactants</em> is<em> limiting</em> the reaction, you need to compare the ratio of the available reactants with the stoichiometric mole ratio from the chemical equation.
The balanced chemical equation is:
The coefficients of each reactant indicate the stoichiometric mole: 4 moles of Al react with3 moles of O₂.
To find the ratio of the available reactants convert the masses in grams to number of moles.
- number of moles = mass in grams / molar mass
The atomic mass of Al is 26.982g/mol
- number of moles of Al = 3.17g / 26.982g/mol = 0.1175 mol
The molar mass of O₂ is 31.998g/mol
- number of moles of O₂ = 2.55g / 31.998g/mol = 0.07969 mol
<u>Theoretical ratio </u>
<u>Ratio of available reactants</u>
<u>Comparison</u>
Since the ratio of the available amount of Al per mol of available O₂ is greater than the theoretical ratio of Al per mol of O₂, there is more available Al than what is needed to react. That implies that when all the O₂ is consumed, there will be some Al left. O₂ is limiting ther reaction.
The reactant that is consumed completely is the limiting reactant, and the reactant that is left is the excess reactant; thus, O₂ is the limiting reactant.