A rigid tank whose volume is 0.5 m3, initially containing ammonia at 208C, 1.5 bar, is connected by a valve to a large supply line carrying ammonia at 12 bar, 608C. The valve is opened only as long as required to fill the tank with additional ammonia, bringing the total mass of ammonia in the tank to 143.36 kg. Finally, the tank holds a two-phase liquid–vapor mixture at 208C. Determine the heat transfer between the tank contents and the surroundings, in kJ, ignoring kinetic and potential energy effects.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.

lol for the pointsss