Molar volumes of CH 3OH, CH 3OD, and CD 3OD, and apparent or excess molar volumes for (methanol-OH + water), (methanol-OD + deuterium oxide), and (methanol-OH + methanol-OD), at 288.15, 298.15, and 313.15 K

Abstract

The molar volumes of CH 3OH and its deutero isomers CH 3OD and CD 3OD have been determined at 288.15, 298.15, and 313.15 K by vibrating densitometry. Apparent molar volumes of { xH 2O + (1− x)CH 3OH} and { xD 2O + (1− x)CH 3OD} for 0 < x < 0.014, and excess molar volumes of { xCH 3OH + (1− x)CH 3OD} for x = 0.24, 0.50, and 0.74 have been measured by the same technique at the same temperatures. The isotope effects are small. At 298.15 K, for example, ln{ V m ∗(CH 3OH) V m ∗(CH 3OD) } = −0.0016 , ln{ V m ∗(CH 3OH) V m ∗(CD 3OD) } = 0.0025 , { V φ ∞(H 2O in CH 3OH) − V φ ∞(D 2O in CH 3OD)} = (0.0±0.3) × 10 −6 m 3·mol −1, and V m E V m < 2 × 10 −5 for { xCH 3OH + (1− x)CH 3OD}. The results are discussed in the context of the theory of isotope effects in condensed phases.