Question

The apparatus below contains ammonia, neon, and hydrogen chloride gases at a temperature
of 27ºC. The valve in the center is opened and the ammonia reacts with the hydrogen chloride:
NH3(g) + HCl(g) → NH4Cl(s)
Neon does not react.
a) What mass of ammonium chloride will be formed?
b) What will be the total pressure in the apparatus after the reaction is complete,
assuming the temperature remains constant?

|volume = 635 mL valve
NH3 pressure = 0.875 atm
Ne pressure = 0.893 atmvolume = 429 mL
HCl pressure =
1.613 atm

Answer 1

a) From the reaction we can see that,

1 mole of NH3 forms 1 mole of NH4Cl

molar mass of NH4Cl = 53.49 g/mol

moles of NH3 reacting n = PV/RT

where,

P = 0.875 atm

V = 0.635 L

R = gas constant = 0.08206 L.atm/mol.K

T = 27 oC = 27 + 273 = 300 K

Feed values,

n = 0.875 x 0.635/0.08206 x 300

   = 0.0226 mole

So mass of NH4Cl formed = 0.0226 mole x 53.49 g/mole = 1.21 g

b) Total pressure of the system = sum of all component pressure

                                                   = 0.875 + 0.893 + 1.613

                                                   = 3.381 atm