Amount-of-substance density of CO 2at temperatures from 329 K to 698 K and pressures up to 34 MPa

New measurements of the amount-of-substance density of pure gaseous CO 2in the temperature range 329 K to 698 K at pressures from 3 MPa to 34 MPa are reported. The results have been obtained by using a fully automated isochoric instrument and their average uncertainty is estimated to be about ±0.05 per cent at the lowest temperatures, rising to ±0.1 per cent at the highest temperatures. Comparisons with the predictions of the recent empirical equation of state of Span and Wagner, as well as with earlier experimental results, which the present work complements, are included. It is shown that the equation of Span and Wagner is probably more accurate than was originally estimated at high temperatures and pressures.