Viscosity of liquids

Viscosity of liquids

Pencil and paper
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Further Resources
This task is about measuring the viscosity of a liquid.
Viscosity of different household substances.  
Step 1 Set up the equipment as shown in the diagram.
 
Step 2
Measure the time it takes for equal amounts of different substances to drop through the funnel.
Write down a plan for how you will do this task.
 
 
 
 
 
  Have this plan checked by your teacher. 
 
Step 3		  
Complete the chart below to show your times and observations.
 
Substance Time Observations
 
 
    
 
 
    
 
 
    
 
 
    
 
 
    
 
 
    
 
Step 4
 
Explain why it took longer for some liquids to move through the funnel.
 
 
 
 
Task administration: 
This task can be completed with pencil and paper and other equipment.
 
Equipment:
Beaker or jar; funnel (a funnel with a diameter of 5 mm was used in trialling); watch with second hand; measuring jug if jar used; a range of liquids (see teacher information).
  • Prior teaching of the concept of viscosity is needed.
  • The liquids given are only examples. In trialling, the liquids used were:
    water, cooking oil, fruit juice, honey, golden syrup, milk, shampoo, Jiff cleaner.
  • The amount of liquid used should be between 20 mL and 50 mL, the funnel size might determine this, e.g., a small funnel may only hold 30 mL.
  • Give students the list of liquids to be tested.
Levels:
3, 4
Curriculum info: 
Science, Investigating in science, Material World
Keywords: 
properties, physical properties, viscosity, fair testing, investigation, practical
Description of task: 
For this practical task students determine the viscosity of different household susbstances such as golden syrup, cooking oil, fruit juice etc. Students complete the experiment and construct a chart showing their results and observations.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask.
 
Capability: Gather and interpret data
This resource provides opportunities to discuss methodologies for fair testing  e.g., what needs to be kept the same and how that might affect the data.
Science capabilities: 
Gather and interpret data
Answers/responses: 

Step 2.

Has a plan that doesn't need modification, e.g., states that they will time how long it takes for a standard amount, e.g., 50 mL of liquid to get through the funnel and into the beaker (probably the better method, but you need marked beakers, the amount students pour into the funnel doesn't need to be measured as long as it is more than 50 mL). An alternative method is to pour 50 mL into the funnel and time how long it takes to go through. Both plans should include some method of blocking the funnel until timing will start, e.g., finger tip blocking funnel exit.

Step 3.

Table completed with at least one relevant observation per substance, and the time unit given.

Step 4.
  • Some liquids do not flow as easily as other liquids.
  • Because some liquids are thicker/more viscous than others.