Question

If 25.0 g of NH₃ and 45.0 g of O₂ react in the following reaction, how many grams of NO will be formed? 4 NH₃ (g) + 5 O₂ (g) → 4 NO (g) + 6 H₂O (g)

Answer 1

Molar mass of NH3,

MM = 1*MM(N) + 3*MM(H)

= 1*14.01 + 3*1.008

= 17.034 g/mol

mass(NH3)= 25.0 g

number of mol of NH3,

n = mass of NH3/molar mass of NH3

=(25.0 g)/(17.034 g/mol)

= 1.468 mol

Molar mass of O2 = 32 g/mol

mass(O2)= 45.0 g

number of mol of O2,

n = mass of O2/molar mass of O2

=(45.0 g)/(32 g/mol)

= 1.406 mol

Balanced chemical equation is:

4 NH3 + 5 O2 ---> 4 NO + 6 H2O

4 mol of NH3 reacts with 5 mol of O2

for 1.467653 mol of NH3, 1.834566 mol of O2 is required

But we have 1.40625 mol of O2

so, O2 is limiting reagent

we will use O2 in further calculation

Molar mass of NO,

MM = 1*MM(N) + 1*MM(O)

= 1*14.01 + 1*16.0

= 30.01 g/mol

According to balanced equation

mol of NO formed = (4/5)* moles of O2

= (4/5)*1.40625

= 1.125 mol

mass of NO = number of mol * molar mass

= 1.125*30.01

= 33.8 g

Answer: 33.8 g