The ice will require two forms of heat: latent to melt and sensible to be heated to 50 °C.
Q(ice) = ml + mCpΔT
= 150 x 333 + 150 x 4.18 x 50
= 85950 Joules
The mass of steam must release this much energy in two forms: latent to fuse into water and then sensible to cool to 50 °C.
85950 = m(2256) + 4.18 x 50 x m
m = 34.9 grams of steam.
Boyle's Law
P1V1 = P2V2
1.8 atm * 2.5 L = P2 * 1.2 L
1.8 atm * 2.5 L / 1.2 L = P2
3.75 atm = P2
Using significant digits, the answer is 3.8 atm
