Question

Ammonia at 10◦c with a mass of 10 kg is in a piston/cylinder assembly with an initial volume of 1 m3. the piston initially resting on the stops has a mass such that a pressure of 900 kpa will float it. now the ammonia is slowly heated to 50◦c. find the final pressure and volume.

Answer 1

Here mass is floating on the piston at equilibrium

So it will have constant pressure always remains constant

So final pressure is same as initial pressure = 900 kPa

now we can say

$\frac{V_1}{V_2} = \frac{T_1}{T_2}$

$\frac{1}{V_2} = \frac{273+10}{273+50}$

$V_2 = 1.14 m^3$

so final pressure is 900 kPa and final volume is 1.14 m^3