Question

The viscosity of liquid acetone is 2.148 cP at -92.5 ^oC and 0.399 cP at ^o0 C. Predict the values of viscosity at -30 ^oC and at 3 0^oC and compare with experimental values of 0.575 cP and 0.295 cP, respectively.

Answer 1

let, viscosity u= A/T +B

A and B are constants and T= absolute temperature

since viscosity is decreaging with temperature, iverse relation is assumed.

at T= -92.5+273.15 K=180.65K

2.148= A/180.65 +B   (1)

at 0 deg.c, 0.399 = A/ 273.15 +B   (2)

Eq.1-Eq.2 , 2.148-0.399 = A*(1/180.65- 1/273.15)

1.749 =A*(0.001875

A= 1.749/0.001875=933

from Eq.2, 0.399 = 933/273.15 +B

B=-3.017

hence u= 933/T-3.017

at -30 deg.c= -30+273.15= 243.15K

u= 933/243.15-3.017=0.622CP

at 30 deg.c

u= 933/303.15-3.017 = 0.060 CP