This question relates to a common concept in Chemistry called "pressure volume work" which measures work done by gases when they compress or expand due to pressure. In equation form work = pressure x change in volume. In this situation work is expressed in L x ATM (atmosphere).
First we calculate the change in volume by subtracting final volume by initial volume. In this case the volume doubled so it is 2v-v which equals v (or 240l).
Next we convert bar to ATM. 1 bar is 100 kilopascale and 101.325 kilo pascals is 1 atmosphere, so in general 1 bar is usually considered to be 1 ATM. If we want to be very precise we would divide 100kilopasczle by 101kilopascalw per bar to get .987 ATM.
In this example we will use 1
So work = 1 ATM x 240l = 240 ATM x l
