# Compressed reversibly and adiabatically problem

hey, i was wondering if anyone could help with this question. it seems simple but i cant find a formula for it.
2.5 mol of perfect gas at 220 K and 200 kPa is compressed reversibly and adiabatically until the temperature reaches 255 K. Given that its molar constant-volume heat capacity, CV,m, is 27.6 J K-1 mol-1, calculate the final volume in L.
many of the equations i have come across need atleast the initial volume so i tried to work out initial volume by pV=nRT which.. gave me an initial voume of 2316.77L

next i used Tf/Ti=(Vi/Vf)^(1/c)
but i got a final answer of 3782L
its a pretty big answer and iit was incorrect.. could someone pls help..

thanks
p.s i also tried to work out the final pressue in kPa and also deltaH.. without any luck. any help would be great!