Question

Calculate the expansion work done on the system when exactly 1 mol of solid ammonium chloride, nh4cl, decomposes completely to yield gaseous ammonia, nh3 and hydrogen chloride, hcl at a temperature of 1250 k. treat the expansion as irreversible and the gases formed as perfect.

Answer 1

The expansion work on an irreversible system is equal to:

W = - PV

 

Assuming that the gas is ideal, therefore:

PV = nRT

 

[P=pressure, V=volume, n=number of moles, R=gas constant, T=absolute temperature]

 

Therefore,

W = -nRT

W = -(1 mol) * (8.314 J / mol K) * (1250 K)

W = -10,392.50 J

 

Therefore about 10,392.50 J or 10.4 kJ of work is done on the system.