Question

When 12 moles of O₂ reacts with 1.1 mole of C10H8 what is the limiting reactant? C10H8 + 12 O₂ -> 10 CO₂ + 4H₂O​

Answer 1

O₂

Step-by-step explanation:

A limiting reactant is the reactant that runs out first in a reaction.

Oxygen

To find the limiting reactant, we can find how many reactions will occur with the given amount of reactant. To do this we can divide moles of the reactant by moles per reaction. If the reaction occurs 1 time, we say that 1 mol of reaction is created. So, the reactant that forms fewer moles of reaction is the limiting reactant.

• Moles of reaction =
  `\displaystyle (12molO_(2) )/(1)*(1molrxn)/(12mol_(2) )`= 1 mol
  `_(rxn)`

This means that with 12 moles of oxygen, 1 full reaction will occur (1 mol of reaction).

Naphthalene (C₁₀H₈)

Now, we can do the same equation with Naphthalene. If it creates fewer moles of reaction, then it is the limiting reactant. If not, then oxygen is the limiting reactant.

• Moles of reaction =
  `\displaystyle (1.1molC_(10)H_(8) )/(1) *(1molrxn)/(1molC_(10)H_(8))` = 1.1 mol
  `_(rxn)`

This means that 1.1 moles of Naphthalene will create 1.1 mol of reaction.

Limiting Reactant

The math above shows that the amount of oxygen given will only create 1 mol of reaction, while the Naphthalene forms 1.1 mols of reaction. Thus, oxygen is the limiting reactant because it creates fewer moles of reaction.