Question

4NH3 + 3O2 ---------> 2N2 + 6H2O

How many grams of H2O can be produced when 30.00 grams of NH3 react with 45.00 grams of O2?

(Correct amount of significant digits)

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)= 30.0 g

use:

number of mol of NH3,

n = mass of NH3/molar mass of NH3

=(30 g)/(17.03 g/mol)

= 1.761 mol

Molar mass of O2 = 32 g/mol

mass(O2)= 45.0 g

use:

number of mol of O2,

n = mass of O2/molar mass of O2

=(45 g)/(32 g/mol)

= 1.406 mol

Balanced chemical equation is:

4 NH3 + 3 O2 ---> 6 H2O + 2 N2

4 mol of NH3 reacts with 3 mol of O2

for 1.761 mol of NH3, 1.321 mol of O2 is required

But we have 1.406 mol of O2

so, NH3 is limiting reagent

we will use NH3 in further calculation

Molar mass of H2O,

MM = 2*MM(H) + 1*MM(O)

= 2*1.008 + 1*16.0

= 18.016 g/mol

According to balanced equation

mol of H2O formed = (6/4)* moles of NH3

= (6/4)*1.761

= 2.642 mol

use:

mass of H2O = number of mol * molar mass

= 2.642*18.02

= 47.59 g

Answer: 47.59 g