We can use the principle of Boyle’s law to calculate the new pressure. Boyle’s law is the piece of the Combined Gas Law that relates pressure and volume:
P1V1=P2V2
STP tells that the standard pressure is 1 atmosphere (P1), and that the 3.52 L (V1) is being compressed to 1.24 (V2).
(1)(3.52)=P2(1.24)
Solving for P2:
P2= 3.52/1.24
P2=2.839
The new pressure of the compressed system is equal to 2.839 atmospheres.