Question

What mass of ammonia is needed to react with 127.2g of oxygen?

Answer 1

Moles of Oxygen = Mass of Oxygen / Molar Mass of Oxygen

$\Rightarrow$ Moles of Oxygen = 127.2 g / 32 g/mol = 3.975 mol

5 mol of oxygen requires 4 mol of ammonia

$\Rightarrow$ 1 mol of oxygen requires (4/5) mol of ammonia

$\Rightarrow$ 3.975 mol of oxygen requires (4/5) x 3.975 mol of ammonia

$\Rightarrow$ 3.975 mol of oxygen requires 3.18 mol of ammonia

Mass of ammonia = Moles x Molar mass of ammonia

$\Rightarrow$ Mass of ammonia = 3.18 mol x 17 g/mol = 54.06 g