The number of moles of oxygen required is 0.499mol.
Given,
Molar Mass of [tex]NH_3 = 14 + 3 = 17g/mol[/tex]
Mass concentration of [tex]NH_3=6.78 g[/tex]
The formula for number of moles :
[tex]n=\frac{Given mass}{Molar mass}[/tex]
We can calculate the moles by using the above formula,
n = 6.78 / 17 = 0.399mol
From the equation,
4moles of [tex]NH_3[/tex] required 5moles of [tex]O_2[/tex].
Therefore, 0.399mol of [tex]NH_3[/tex] required x moles of [tex]O_2[/tex].
X mol of [tex]O_2 = (0.399\times 5) / 4 = 0.499mol[/tex]
Find more information about number of moles here,
brainly.com/question/12513822
