Question

How many grams of H2 are needed to produce 12.32 g of NH3?

Answer 1

2N2 + 3H2 ----> 2NH3

Molar mass of NH3 = 17 g/mol
mass of NH3= 12.32 g

number of moles of NH3 = mass / molar mass
                                                   = 12.32 / 17
                                                   = 0.725 mol

From equation above,
2 mol of NH3 requires 3 mol of H2
So,
number of moles of H2 required = (3/2)*0.725 mol = 1.09 mol

Molar mass of H2 = 2 g/mol
mass of H2 = molar mass * number of moles
                       = 2* 1.09
                        =2.2 g
Answer: 2.2 g