Question

4al + 3o₂ → 2al₂o₃
what conversion factor is missing from the
dimensional analysis?
16 g o₂ | 1 mol o₂ | 4 mol al | ? = ?

32 g o₂

3 mol o₂

? g al

options:
27 g al / 16 g o₂
27 g al / 1 mol al
1 mol al / 27 g al

Explanation:

Step1: Identify the goal

We need to find the conversion factor to convert moles of Al to grams of Al. The molar mass of Al is used for this conversion. The molar mass of Al is approximately 27 g/mol, so the conversion factor from moles of Al to grams of Al is $\frac{27\ \text{g Al}}{1\ \text{mol Al}}$.

Step2: Analyze the given steps

We have moles of Al from the stoichiometry ($\frac{4\ \text{mol Al}}{3\ \text{mol O}_2}$) and we need to convert moles of Al to grams of Al. The correct conversion factor should relate moles of Al to grams of Al, which is the molar mass of Al, so $\frac{27\ \text{g Al}}{1\ \text{mol Al}}$.

Answer:

$\frac{27\ \text{g Al}}{1\ \text{mol Al}}$ (the middle option: $\frac{27\ \text{g Al}}{1\ \text{mol Al}}$)