2NH4Cls CaNO32s 2N2Og CaCl2s 4H2Og If 950 g NH4Cls reacts

2NH₄Cl(s) + Ca(NO₃)₂(s) 2N₂O(g) + CaCl₂(s) + 4H₂O(g)
If 95.0 g NH₄Cl(s) reacts completely and the gas is collected in a (previously empty) 150.0 L flask at 351 K, what is the total pressure of gas?

Solution

Balanced equation:
2 NH₄Cl(s) + Ca(NO₃)₂(s) ===> 2 N₂O(g) + CaCl₂(s) + 4 H₂O(g)

95.0 g NH4Cl(s) = 95 /53.49 = 1.775 Moles

Moles of N2O gas produced = 1.775 Moles

Moles of H2O gas produced = 3.551 Moles

Total moles of gases produced =  3.551 + 1.775 = 5.326 Moles

PV= nRT

P = Pressure in atm                       V= Volume in Liter

n = no of moles               R = 0.0821 L atm K-1 Mol-1

T = Temperature in Kelvin

Using the equation we can calculate the total pressure

V = 150 L n = 5.326 Moles T = 351 K

P = 5.326 x 0.0821 x 351 / 150 = 1.02 atm

Hence the total pressure of gases is 1.02 atm