Critical parameters for 2-methylpropane (R600a)

Measurements of the vapor-liquid coexistence curve near the critical point for 2-methylpropane (isobutane; R600a) were carried out in the reduced temperature range of 0.957 < T/T-c < 1 and in the reduced density range of 0.40 < p/p(c) < 1.70, and the critical temperature T-c and critical density p(c) were determined. The critical pressure P-c was calculated by extrapolating reliable vapor-pressure data in the vicinity of the critical point. The critical parameters determined are T-c = (407.795 +/- 0.010) K, p(c) = (229 +/- 2) kg.m(-3), V-c = (253.8 +/- 2.2) cm(3).mol(-1), and P, = (3628.2 +/- 1.4) kPa. In addition, the critical exponent P along the coexistence curve is discussed.