Drexel University

CHEM 253

1. Consider an argon gas in a metal container at a temperature of 70 °C. The size (side length) of the cubic, metal container is 2.5 m. Calculate the pressure of the gas as a function of its density for the ideal and real gas (van der Waals) approximation. Produce plots that visualize the dependence of the pressure on density. Above what density do the slope and the pressure value of the ideal and real gas differ by more than 10 percent? (10pts.) Answer: For ideal gas we assume that density is constant throughout the container. PV=nRT; ρ=m/v; n=m/M; P = ρRT/M For real gas we assume that density, as molar properties, are constant throughout the container. Given aargon(gas) = 1.355dm6bar mol-2 and bargon(gas) = 0.0320 dm3mol -1 and the molar mass of Argon as 39.948g/mol: P = - ; Vm = ; P = - nRT V − nb n a 2 V 2 ρ M ρRT M − bρ M 2 ρ a