The unit J Pa-1 is equivalent to

JPa-1; Unit of work is Joule and unit of pressure is Pascal.  Dimension of Joule i.e. work =F×L=MLT−2×L=ML2T−21Pa=1 Pressure =1FA=1×AF=ML-1T−2 So,     J Pa−1=ML2T−2ML-1T-2=L2×L  =  L3   = volume in S I units .