Liquid ethanol shows the following measured viscosities at several temperatures:
Temperature (°C)
Viscosity (mPa·s)
20
1.20
30
0.97
40
0.79
60
0.55
Answer the questions that follow.
(a) Using the data, determine the approximate percent decrease in viscosity when the temperature is raised from 20 °C to 40 °C.
(b) Assuming a linear relationship in the temperature range given, estimate the viscosity of ethanol at 50 °C.
(c) Explain, on the particulate level, why increasing the temperature causes the viscosity of ethanol to decrease.
(d) Predict how the temperature dependence of viscosity for ethanol would compare with that for propane-1,2-diol (HOCH2CH(OH)CH3). Justify your prediction.