The temperature dependence of surface tension and viscosity has been investigated in two multi-component liquid hydrocarbons, namely, crude oil samples with different API numbers. The surface tension is found to decrease linearly with temperature whereas viscosity exhibits Arrhenius type variation. These measured values along with the ultrasound velocity, density and the isothermal compressibility have been used to estimate a number of physical parameters such as the activation energy, attenuation factor and the shear wave velocity. Crude oil with larger API was found to have smaller activation energy. Shear velocity decreases exponentially with increasing temperature while the attenuation factor is found to increase linearly with temperature. The ratio of the surface tension to viscosity varies linearly as the square root of temperature. The product of the surface tension and the isothermal compressibility, often characterized as a fundamental or correlation length of the surface of the liquid, was found to yield a constant value for both samples.
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