Viscosity of N-pentane, N-heptane and their mixtures within the temperature range from 298 degrees K up to critical points at the saturation vapor pressure

The viscosity of n-pentane, n-heptane and their mixtures has been measured with a capillary flow method between 298 K and the critical temperatures at the saturation vapor pressure. The concentrations studied were 0.259, 0.419 and 0.745 mole fraction of n-heptane. The maximal error of the experimental values of the viscosity is estimated to be +/-1.2% in the region far from the critical point and +/-5% in the immediate vicinity of the critical point. The viscosity obtained was compared to data by other authors with satisfactory agreement. The validity of the method has been confirmed by the measurement of the viscosity of standard liquids as water and toluene.