We assume ideal gas behaviour so we can use the formula:
PV = nRT
From the problem, we can say that the amount of Helium
does not change so n is constant and that we assume no change in temperature so
that T is also constant, therefore:
P V = constant
And then:
P1 V1 = P2 V2
765 torr * 3.00 L = 70,661 Pa (760 torr / 101325 Pa) * V2
V2 = 4.33 L
