Rate of Flow of Liquid Investigatory Project

Investigatory Project on comparative study of the rate of flow of liquids

Introduction: Liquids have flow properties. Some liquids flow faster than some others. This difference in the rate of flow of liquid is due to a property called viscosity. Viscosity of a liquid is its resistance to flow. A liquid with high viscosity will flow comparatively slowly. Viscosities of different liquids can be compared in terms of coefficient of viscosity. It is described as the force in dynes per square centimeter necessary to maintain a difference in velocity of 1 cm per second between two parallel layers of liquid held at a distance of 1cm from one another. It is denoted by η and expressed in millipoise. The rates of flow of liquids are compared by taking them in a viscometer and allowing them to flow through a fixed distance and measuring the time taken in each case.

Objective: The objective of this project is to compare the rates of flow of different liquids such as water, coconut oil, benzene, glycerine etc.

Requirements: Viscometer, Stop watch, Liquids like water, coconut oil, benzene, glycerine etc.

Procedure: Take one of the liquids, say water (about 25mL) in the bulb 'A' of a clean and dry viscometer. Suck up the liquid into bulb 'B' so that it is slightly above the mark 'C' of the viscometer. Allow the liquid to fall through the capillary. Note the time taken for the meniscus of the liquid to fall from the mark 'C' to 'D' by using a stop watch. Repeat the experiment three times with the same liquid. Wash and dry the viscometer. Repeat the above experiment with the other liquids and tabulate the results.

 Liquid Time taken Density d η liquid/ η water t1 t2 t3 Mean t Water - - - - Coconut oil - - - - Benzene - - - - Glycerine - - - -

η liquid/η water can be calculated using the relationship.

η liquid/η water = t liquid/t water x d liquid/d water

Where t liquid and t water are the time taken for the flow of liquid and water respectively and d liquid and d water are the densities of the liquid and water respectively.

Conclusion:

Liquids which flow readily have low viscosity, while those which flow slowly have high viscosity.

1. What is viscosity of a liquid?

Ans: Resistance to the flow of a liquid is known as viscosity.

2. Which has higher viscocity, water or coconut oil?

Ans: Coconut oil

3. Which instrument is used to measure viscosity?

Ans: Viscometer

4. Why is coconut oil more viscous than water?

Ans: Different liquid layers in coconut oil are attracted by hydrogen bonding.