Question

Why does an increase in temperature cause a decrease in viscosity in liquids and an increase in viscosity in gases?

Answer 1

see below

Explanation:

for gases, the viscosity is given by the collisions of the molecule among them. Since, as the temperature rises, rises also velocity and the probability of collisions, viscosity grow up.
`E_k=1/2 m v^2` kinetic energy
`E_k= K T`kinetic energy
therefore
`v = sqrt (2KT/m)`
For liquids instead as the temperature grows up, decrease the intermolecurar coesions forces among the molecules and liquids flow better.
there are no formulas