# Question eee62

May 15, 2017

$0.246 {\text{mol of H}}_{2}$

#### Explanation:

To use Dimensional Analysis (the Factor-Label Method), you begin by writing the given quantity over 1:

$\frac{0.123 {\text{mol of O}}_{2}}{1}$

We observe that two moles of hydrogen are need for 1 mole of oxygen, therefore we multiply by that conversion factor:

$\left(0.123 {\text{mol of O"_2)/1(2"mol of H"_2)/(1"mol of O}}_{2}\right)$

Please observe how the units cancel:

$\left(0.123 \cancel{{\text{mol of O"_2))/1(2"mol of H"_2)/(1cancel("mol of O}}_{2}}\right)$

We may stop and perform the multiplication, because the only unit that remain are the desired units:

(0.123cancel("mol of O"_2))/1(2"mol of H"_2)/(1cancel("mol of O"_2)) = 0.246"mol of H"_2#