Viscosity Measurements with the Falling Ball Viscomete

PURPOSE:

The purpose of this experiment is to measure viscosities of methanol - water mixtures

which have different weight fractions of methanol and is to measure viscosities of methanol

and water for different temperatures in order to examine effect of temperature on viscosity.

OBSERVATION:

The falling times of the ball were measured for water and methanol at seven different

temperatures. The falling times are smaller for methanol than water at the same

temperature. On the other hand, falling times increases as the weight percent of water

increases. When the temperature increases, falling times decreases for both methanol and

water. According to obtained data, viscosities of water, methanol and their mixtures were

calculated.

CALCULATIONS:

W(Methanol) X(Methanol) Viscosity

0 0 0,59

0,1646 0,05 0,75

0,3442 0,13 0,86

0,5425 0,23 0,84

0,7597 0,38 0,66

1 0,61 0,46

Temperature 1/T (K-1) Viscosity(Methanol) Viscosity (Water)

20 0C 0,0034 -0,65 -0,534

25 0C 0,003354 -0,66 -0,522

30 0C 0,003298 -0,68 -0,555

35 0C 0,003224 -0,71 -0,622

40 0C 0,003193 -0,74 -0,633

45 0C 0,003175 -0,8 -0,673

50 0C 0,003094 -0,83 -0,73

Equation of 1/T versus ln(η) graph for water: y = 694,56x - 2,866

Equation of 1/T versus ln(η) graph for methanol: y = 613,78x - 2,718

η = E/R * 1/T – lnC

For water: E/R=694,56, E=57.74 kJ.mol-1

Error =( I15.9 kJ.mol-1 – 5.774 kJ.mol-1I / I15.9 kJ.mol-1) * 100 = 64.1 %

For methanol: E/R=613,78, E=5.1029 kJ.mol-1

Error =( I11.1 kJ.mol-1 – 5.1029 kJ.mol-1I / I11.1 kJ.mol-1) * 100 = 54 %

DISCUSSION: