Abstract

Objective

In this experiment you will make your own homemade silly putty. By varying the ratio of ingredients and by observing physical properties, you can determine the best recipe for the putty.

Introduction

You might think that chemists are a bunch of boring scientists who wear lab coats and look at beakers all day, but did you know that many toys you play with are made using chemistry? Some of your favorite toys like Gak, Slime and Silly Putty started out as chemistry experiments. In fact, some of your favorite toys may have been invented by chemists who work for toy companies like: Crayola, Play-Doh or Mattel.

Chemistry is the study of matter, and how different elements of matter interact. There are many different kinds of matter, which need to be described using the concept of properties. Toys like silly putty are unique because of they have distinct properties that are different from the properties of other types of matter. There are two different kinds of properties, chemical properties and physical properties.

Chemical properties are qualities that can be observed during a chemical reaction, like when vinegar reacts with baking soda. Physical properties are qualities that can be observed during physical change in the absence of a chemical reaction, like the melting of an ice cube. Physical properties can be used to describe the state of a chemical, which can be a solid, liquid or a gas. The physical and chemical properties of Silly Putty are what make it so much fun because it is a polymer that is stretchy and bouncy!

Scientists use properties to describe all of the unique qualities of a chemical or a mixture of chemicals. To do this they use descriptive language, or words that are used to describe objects. Some descriptive words used to describe a chemical might be: hot, cold, squishy, hard, soft, crystalline, granular, smooth, liquid, clear, opaque, runny. There are many different qualities to be described. You just need to find the right words to use.

The unique physical and chemical properties of a polymer or mixture can be changed by the amount of each different ingredient used to make them. Sometimes the amount of one ingredient compared to the amount of another ingredient can make a big difference. This is called a ratio, and a ratio can be useful to know how much of each ingredient to add to your mixture so you will end up with a mixture that has desirable properties.

In this experiment you will change the ratio of two basic ingredients in homemade Silly Putty. You will describe the physical properties of each different mixture using a data table. Then you will choose the ratio of ingredients to create the best putty product.

Terms, Concepts, and Questions to Start Background Research

To do this type of experiment you should know what the following terms mean. Have an adult help you search the internet, or take you to your local library to find out more!

• chemical
• chemical property
• physical property
• solution
• mixture
• polymer
• ratio

Bibliography

• Learn everything you ever wanted to know about Silly Putty. Find out Silly Putty history, uses, products and science:
  2000. Silly Putty U.: The Home of Higher Silly Putty Learning. Binney & Smith, Inc. Easton, PA. 12/13/05.
  http://www.sillyputty.com/
• Here is a great site for learning about polymers:
  2003. Making Things Out of Polymers. Polymer Science Learning Center, Dept. of Polymer Science, University of Southern Mississippi. 12/13/05.
  http://www.pslc.ws/macrog/kidsmac/kfloor3.htm
• This web site at Chemistry 4 Kids has a great tutorial on chemistry, matter properties and mixtures. Go check it out:
  Rader, Andrew. 2005. Rader's Chem4Kids. Andrew Rader Studios. 12/13/05.
  http://www.chem4kids.com/files/matter_intro.html

Materials and Equipment

• Zip-lock baggie
• water
• Elmer's® School Glue
• Borax (also called 20-Mule Team household cleaner); See "Local Resources for Purchasing Common Chemicals" on our Guide to Purchasing Chemicals page. Safety Note: Borax is harmful if swallowed. It is uncommon, but possible, for borax to cause skin rashes. Gloves can be used to avoid skin contact.
• measuring cups and spoons
• two recycled glass jars with a lid
• permanent marker
• Gloves, latex or similar style exam glove (optional). Can be used if there is concern over handling borax.
• Food coloring (optional)

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Experimental Procedure

1. First you will need to prepare the 50% glue solution, which is made up of half glue and half water.
2. Add one cup of glue and one cup of water to one of the jars.
3. Tightly secure the lid to the jar and shake until glue is fully diluted, and no gooey clumps remain.
4. Using a permanent marker, label this jar "50% Glue".
5. Next, you will make the Borax solution, which is made up of 4% Borax in water. Usually you would weigh the borax, but you can approximate this solution by adding 2 tsp Borax to 1 cup of warm water to a jar.
6. Tightly secure the lid to the jar and shake until no particles of Borax remain, and the solution is clear.
7. Using a permanent marker, label this jar "4% Borax".
8. Now we will add the 50% glue and 4% Borax solutions together in different ratios, to see what properties the final mixture will have. First we need to make a data table.

9. For each mixture, first add the correct amount of the 50% glue solution to a Zip-lock baggie.
10. Then add the corresponding amount of the 4% Borax solution to the baggie.
11. Seal the baggie, and using your fingers squish the mixture around to mix together the ingredients.
    1. For fun: Try adding food coloring to the mixtures before mixing. Make sure to add the same amount of food coloring to each mixture so that the coloring is a controlled variable.
12. Write down your observations in your data table.
13. When the mixture begins to form a sticky glob, you can take it out of the baggie.
14. Write down your description of the physical properties of the material in your table. Remember to use words like runny, slimy, sticky, hard, soft, bouncy, etc.
15. Which ratio of ingredients produced the best product? What will you call your new product?

Variations

• Are there other ways to change the recipe in order to change the physical properties of the putty? Try changing the percentages of glue or Borax in the solutions to see how that changes your product. Can you optimize the recipe in new and different ways to obtain different types of products?
• Another polymer is the protein gelatin found in Jello. What experiments can you conduct to explore the physical properties of gelatin?
• A common use for polymers is to make thin sheets of material for holding things, for example plastic shopping bags, garbage bags, Zip-lock baggies or balloons. Can you design a series of experiments to test these different materials? Are some materials stronger, or more puncture resistant? How do the properties of the material make it a good useful product?

• For more science project ideas in this area of science, see Chemistry Project Ideas.

Credits

Sara Agee, Ph.D., Science Buddies

Last edit date: 2012-02-14 13:50:44