Chemistry Forum

A closed container contains 7.0g of oxygen gas (O₂), at room temperature. More oxygen was added to the container wherein pressure was maintained through adjusting its volume. If the volume was adjusted from 2.5L to 3.5L how many grams of oxygen was added in the container??

What the law is?
The formula?(so i can solve)

Ideal Gas law
pV = nRT
In this case, p,R and T = const.
V~ n
Change n of Oxygen to mass. m = n*M
V ~ m