EXPERIMENT 3 DATA REDUCTION : The Viscosities and Densities of MIxtures

The Viscosities and Densities of Mixtures

VISCOSITY Viscosity – the ease of a material to flow F = Force A = Plate Area h = distance between plates

Solving for viscosity, ƞ, from equation (2) gives equation (3)

Units for Viscosity Using the SI units from the equation (3) above taking units for force to be in dynes, distance in cm, velocity in cm/sec ; 10 5 dynes = 1 newton (N) 10 4 cm 2 = 1 m 2 So 1 cm 2 = m 2 1 N/m 2 = 1 Pascal (Pa) SINCE : 1 Pascal second (Pa)(sec) = 1 (N)(sec)/(m 2 ) THEREFORE : 1 P = 0.1 Pl

VISCOSITY OF SOME SUBSTANCES

VISCOSITY OF WATER AT DIFFERENT TEMPERATURES The higher the temperature the lower the viscosity of water!

Determining Viscosity from the Time of Flow of a Constant Volume of Liquid GRAVITY Relationships : The higher the density, the greater the force on the liquid The greater the force the greater the velocity of flow The greater the velocity the less the time taken for liquid to flow out of the burette So, the greater the density the less the time taken for liquid to flow out of the burette POISEUILLE LAW If same burette is used, the equation below applies where, B is a constant, d = density, t = time to flow, ƞ = viscosity Equation (7) ƞ /d = Bt (for a fixed volume of liquid)

Example of Mole Fraction of Alcohol in Alcohol/Water mix Equation (7) ƞ /d = Bt NOTE : The calculated B value above only applies to the Specific burette used!!!!!!!

Given : The 36 ml alcohol /36 ml water mixture with a density of 0.93 g/ml, and time of flow of 52.5 seconds, the viscosity can be calculated as below Equation (7) ƞ /d = Bt Also expressed as - ƞ = d x B x t

To justify that the total mass of the alcohol water mixture is not 72 ml…………………………………

Example of Data Table and Expected Graph Plots

Method 2 : Pycnometer Watch this video