Question

Question #eee62

Answer 1

`0.246"mol of H"_2`

Explanation:

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

`(0.123"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:

`(0.123"mol of O"_2)/1(2"mol of H"_2)/(1"mol of O"_2)`

Please observe how the units cancel:

`(0.123cancel("mol of O"_2))/1(2"mol of H"_2)/(1cancel("mol of O"_2))`

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`