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RESEARCH PRODUCT

Apparent molar volumes of 1-pentanol in water fromT=298 K toT=413 K atp=0.1 MPa andp=19 MPa

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Abstract Densities of 1-pentanol aqueous solutions were measured by using a vibrating tube densimeter especially designed and equipped to perform accurate measurements from ambient conditions up toT=423 K andp=80 MPa. The densimeter was tested by measuring densities of NaCl (aq). A comparison with the most reliable literature data showed very good agreement with differences lower than (0.03 and 0.1) kg·m−3for molalities below and above 0.5 mol·kg−1, respectively. From the density measurements, the apparent molar volumes of 1-pentanol in water,Vφwere determined as a function of molalitymat temperatures fromT=298 K toT=413 K atp=0.1 MPa andp=19 MPa. At a given temperature and pressure, and partial molar volume of 1-pentanol at infinite dilutionVφ0was calculated by a linear fit to theVφagainstmdata.Vφ0increases with the temperature at bothp=0.1 MPa andp=19 MPa and it shows a negative pressure dependence in the whole investigated temperature range. The temperature and pressure dependence ofVφ0is consistent with the hydrophobic nature of 1-pentanol.