At room temperature, all three real gases have a pressure less than the ideal gas. which van der waals constant, a or b, accounts for the influence intermolecular forces have in lowering the pressure of a real gas? at room temperature, all three real gases have a pressure less than the ideal gas. which van der waals constant, or , accounts for the influence intermolecular forces have in lowering the pressure of a real gas? a b both a and b