Question

Which one in each of the following pairs of liquids is more viscous: glycerine, kerosene.

Answer 1

Hint : The resistance that is offered by a fluid when it is subjected to deformation or allowed to flow is known as viscosity. Both liquids and gases show this property but in liquids, it is more pronounced and highly affects its mechanical and physical properties. Both glycerine and kerosene are liquids at room temperature.

Complete Step By Step Answer:
In the case of liquids, the larger the intermolecular forces the higher is the viscosity. Some other factors like temperature and molecular shape also affect viscosity. The viscosity of a substance decreases with increase in temperature. At higher temperatures, the force of attraction between the molecules decreases and kinetic energy will be higher. As a result, the viscosity decreases. The shape of the molecules also affects viscosity because molecules with many branches will not slide by one another easily when compared to small round molecules. Viscosity is also affected by hydrogen bonding. As hydrogen bonds form and break during the motion of molecules of water, the hydrogen bonding dominates the intermolecular forces and influences the viscosity. There is extensive hydrogen bonding in glycerine, so it is more viscous than kerosene.
Therefore, glycerine is more viscous.

Note :
Note that viscosity will be higher if intermolecular forces are higher. If there is a strong intermolecular force, the molecules present in the liquid will be bonded strongly to each other. This will induce resistance to move. So, the liquids whose molecules or polar or those which form hydrogen bonds are more viscous.