ABSORBENCY OF SPONGES - YES I Can! Science

ABSORBENCY OF SPONGES

Context
Three different types of sponges are available at your local store. You want to
know which type will absorb the most water.

You should have the following materials:
• 3 small sponges of different size and composition
• 1 ruler
• 1 plastic funnel
• 1 graduated cylinder (50 mL)
• 1 beaker (250 mL)
• 1 calculator
• 1 aluminum work tray
• plastic forceps
• water supply

Task
4-1. Based on the Context above, identify the problem you are investigating.

________________________________________________________
________________________________________________________
_______________________________________________________
_______________________________________________________

27

4-2. Write the steps you could use to solve the problem you stated in question 4-1.
Use only the materials given to you.

________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________

4-3. Carry out your procedure from question 4-2. Record your data in the space below.

c

Volume = a × b × c b

1.a16 ' 0.66 '

28

4-4. Using your data, write a solution to the problem you stated in question 4-1.
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________

4-5. One way to improve the reliability of your results would be to use sponges of the
same size. Suggest another change that would improve the results of this
experiment.
________________________________________________________
________________________________________________________
________________________________________________________
Explain how your change would improve the reliability of the results of this
experiment.
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________

4-6. Determine the reliability of your results. Use mathematical data to justify your
answer.
_______________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________

29

Special Instructions for Laboratory Set-Up

• To make this task comparable for all students, place the sponge samples in water and
leave them wet in the work tray for the first students who use the station.

30

Scoring Guide

Level 1: Identify the problem to be solved as given in the context.

To determine which type of sponge absorbs the most water.

Level 2: Design a simple procedure.

An acceptable procedure must resolve the experimental problem, provide sequenced
steps, and incorporate appropriate use of materials and equipment. Scoring note: The
procedure must include these two steps:
• Get the water out of the sponge.
• Measure the water.

Level 3: Draw conclusions from data.

The conclusion identifies which of the three sponges absorbed the most water and is
based on the student’s data, whether the data are realistic or not.

Level 4: Suggest an improvement to an experimental design.

A specific way to improve the results is combined with an explanation of how this
method improves the results.
Possible improvements
• an improved means of extracting the water
• less handling or more uniform handling of the sponges
• more repetitions of procedures

Level 5: Evaluate the reliability of data gathered using qualitative and quantitative
methods.

A response supported by quantitative data is used in assessing the reliability of the
results. The response must include
• a judgment about the reliability of the results
• a calculation of the volume of water absorbed per cubic centimetre of sponge
(Evidence for the mL/m3 calculation may be found in 4-3 or 4-4)

31

Extension
The diffusion of a weak sodium hydroxide solution in an agar-agar gel.
Material
• a NaOH solution 0,10 M
• an agar-agar gel to which has been added a few mL of phenolphthalein during the

preparation
• 5 100-mL beakers, labelled from 1 to 5
• a pair of plastic tweezers
• a mm ruler
• a knife or a scalpel
• a stopwatch
Method
• Pour 80 mL of the NaOH solution into each beaker.
• Cut out 5 identical agar-agar cubes 2 cm x 2 cm x 2 cm.
• Put a cube in beaker # 1; wait for 30 s.
• Withdraw it and measure the distance to which the pink color diffused inside.
• Repeat preceding operation with cubes # 2, 3, 4, and 5 respectively for 60,

90, 120, and 150 s.
• In each case determine the speed of diffusion of the sodium hydroxyde solution

into the agar gel. Then calculate the mean velocity of diffusion.
• For this experiment, indicate the handled variable, the reacting variable, and the

controlled variables.
• Indicate two sources of error that could affect the results of your experiment.

32