Science project

Getting The Soap Out!

Approximate Time Required to Complete the Project

1 to 2 weeks. This includes collection, recording and analysis of data, summary of results and completion of bibliography.


To design and conduct an experiment to determine which of the following substances, table salt, Epsom salt, sugar or baking soda would be most effective in removing soap from water?

Materials and Equipment Required

Water, powdered soap, Epsom salt, sodium chloride (table salt), sugar, baking soda, 5 plastic cups or glass jars,  a large beaker, a graduated cylinder, 5 test tubes and holder, ruler, plastic spoons, stirrers, a watch with second hand, filter paper, a funnel,   scissors, safety glasses, apron or shirt to serve as lab coat and paper towels.


Background Information

On the information level, this experiment serves to acquaint students with current information on a major waste and recycling question, how to remove soap and detergent from water. Students test various chemicals and discover how the process of precipitation is utilized to remove the soap and restore the water for future use.

On the level of experimenting, this project serves to acquaint students with the essential processes of sciencing such as the importance of the use of a control, of identifying dependent and independent variables, of data collection, of pictorial and graphic presentation of data and of being able to make better judgments as to the validity and reliability of their findings. They take on the role of scientists and in the process they learn to act as one.

Research Terms
water pollution
water purification
water softening
water quality
water treatment
hard water
soft Water
physical change
chemical change

Research Questions

  • How do water purification plants remove soap from water?
  • Do powdered soaps form solutions when added to water?
  • What are powdered soaps made of?
  • Are there chemicals that are used specifically to remove soap and soap scum from water, from different surfaces such as shower doors and bathtubs?  
  • What is filtration?
  • How is filtration used in water purification?

Terms, Concepts and Questions to Start Background Research

  • What is a control?  A control is the variable that is not changed in the experiment.
  • What purpose does a control serve? It is used to make comparisons as to what changed or possibly caused the change.
  • What are variables?  Variables are factors that can be changed in an experiment.
  • What is an independent variable? The independent variable is the one that is changed in the experiment.
  • What is a dependent variable? The dependent variable is the one that changes as a result of the change in the independent variable.

Experimental Procedure

  1. State the problem you are going to investigate in this science fair project.
  2. Create and reproduce the data sheets you u will use to record your observations.
  3. Gather all your materials.
  4. Put on your safety glasses, rubber gloves and apron.
  5. Make the soapy water by adding one plastic spoonful of soap powder to 250 mL of water. Stir well.
  6. Pour 50 mL of the soapy water into each of the 5 jars and label each jar with a number.
  7. Assign a chemical additive label to each number. For example, jar 1, table salt, jar2 Epsom salt, jar 3 sugar, jar 4baking soda and jar 5 the control.
  8. Using separate plastid spoons, add one spoonful of table salt to jar 1, one spoonful of Epsom salt to jar 2, one spoonful of sugar to jar 3, one spoonful of baking soda to jar 4 and nothing to the control, jar 5.
  9. Using separate stirrers, stir each jar and the allow them to sit for five minutes.
  10. Observe all five jars and record your observations on your chart.
  11. Place a coffee filter in your funnel, replace the filter for each jar and, filter the contents of each jar separately. Let sit for five minutes.  Record your observations.
  12. Analyze your data and state and record your conclusion.
  13. Prepare your report and include all of the following: a clear statement of the problem, your hypothesis and the rationale for your hypothesis. List the materials used. Include the safety precautions taken. Describe the procedures used. Include all the data that were gathered. Include all charts and/ or graphs. Formulate your conclusions. Assess how accurate you think they were?  For dramatic value, you may include photos of the materials used or of you in the process of conducting this investigation. Include a bibliography of sources you used. You may wish to assess what you did and describe what you would do differently if you were to do this project again.

Charting and/or Graphing Data

In each section of the experiment, use charts to display the obtained data such the following sample:

Observations Before Filtration
Observations After Filtration

jar #1


jar #2


jar #3


jar #4


jar #5



Capt Science Performance Test, released item, Connecticut State Department of Education

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