A Burnett apparatus for the accurate determination of gas compressibility factors and second virial coefficients, and an evaluation of its capability based on some results for argon and carbon dioxide

Abstract

A Burn e tt a ppa ratu s has been deve lu pe d for th e de te rmina ti un uf th e cumpress ibilit y fac tu r uf gases, includin g corrus ive ha loge ni c gases, to a n accurac y of 0.1 pe rce nt to 0.01 pe rcent at te mpera tures fro m 0 to 225 °C and for pressures up to 250 ba rs. T he a ppa l'a tus has bee n used throughout thi s te mpe ra ture and press ure range and a t te mpe ratures within 15 °C of the c riti ca l te mpe ra ture of the sa mpl e gas. T he a ppa ra tu s fea lures a rugged ye t highl y sens iti ve and re prod ucibl e null-Iype press ure transdu ce r to isula te the sa mple gas witho ut inlrud uc in g a pressure uncert a int y grea te r tha n th e prec ision of the press ure measureme nts, whic h is be tt e r th an 1 pa rt in 50 ,000. The press ure measure ment s a re acc ura te to at leas t I pa rt in 20 ,000. Th e reduction of the da ta is di scussed ex tens ive ly. Th e ca pa bility of th e a ppa ra tu s ha s been evalua ted in te rm s of the compress ibilit y fac tor represented by a finit e pressure or densit y vi rial expans ion a nd de rived from a rgo n da ta a t 25 °C a nd press ures up to 250 ba rs and in te r ms of the secund vi ri a l cue ffi cie nt of ca rbon diox ide based on data at 50 °C a nd pressures be low 35 ba rs. Th e va lu e ubt ain ed fur thi s secund viria l c~e fli c i e nl. 102 .2 ± O.2 cm"/ mol. com pa res fa vora bl y with th e va lue uf 102.5 c m"/ mol ob ta in ed fro m a rece nt correla ti on a nd is in s ubstanti a l di sagree ment with th e va lu e of 100.7 ± O.4 c m "/ mol de te rmin ed by Dad so n a nd cu· wo rk e rs fro m th e Burn e ll me thod and the pie zo me te r me thod .