if you have a capsule thats 2 cubic inches and has 5 PSI of compressed air?

Question

If you release the air from the capsule, how many cubic inches of air will you have?

Answer 1

I don't fully understand your question, but it appears the compession is 5 psi GAGE rather than ABSOLUTE, which is the usual basis in gas problems in physics. So if the capsule air is released to the atmosphere, its pressure will drop from 5psi+14.7psi or 19.7 PSIA to 14.7 PSIA, and the volume will increase proportionately.

Answer 2

P1 x V1 = P2 x V2 (P = Absolute)

2cu.in x 19.7psia = V2 x 14.7psia
V2 = 2 x 19.7 ÷ 14.7
= 2.68 in³. (2.7in³).

(It will, of course, dissipate into the atmosphere)