The van der Waals equation if state is given by P = { (RT) / (V-b)} - [a/V^2 ] where P is pressure, T is temperature, R is the gas constant, and a and b are substance specific parameters (they are constants). If the pressure is expressed in units of bar and volume in cm3/mol , for this equation to be dimensionally consistent, what would be the units of b and a? Show your work .