Question

Use the following reaction to answer the questions below NH4NO2(s) --> N2 (g) + 2H2O(g)

1) What is the volume produced when 37g of NH4NO2 decomposes at 45oC and 0.78 atm

2) what is the partial pressure of nitrogen in this reaction

Answer 1

Sol.

Reaction : NH4NO2(s) ----> N2(g) + 2H2O(g)

(1) Moles of NH4NO2

= mass of NH4NO2 / molar mass of NH4NO2

= 37 g / 64.06 g/mol = 0.5776 mol  

From reaction , moles of H2O = moles of NH4NO2 × 2

= 0.5776 mol × 2 = 1.1552 mol  

moles of N2 = moles of NH4NO2 = 0.5776 mol

Total moles = n =   moles of H2O + moles of N2

= 1.1552 mol + 0.5776 mol = 1.7328 mol

Gas constant = R = 0.0821 L atm / K mol

Temperature = T = 45 °C = 45 + 273.15 K = 318.15 K  

Total pressure = P = 0.78 atm  

Total Volume produced = V = nRT / P

= 1.7328 mol × 0.0821 L atm / K mol × 318.15 K / 0.78 atm

= 58.03 L

(2)

Mole fraction of N2 gas = moles of N2 / total moles

= 0.5776 mol / 1.7328 mol = 0.333  

Partial pressure of N2 gas  

= Mole fraction of N2 gas × Total Pressure

= 0.333 × 0.78 atm

= 0.259 atm