Homemade Rubber Ball (Guest Post)

That’s right! A homemade rubber ball! Today’s guest post comes from All Things Beautiful. Phyllis homeschools her five beautiful children and posts about some amazing projects. I also love that her posts include easy to follow tutorials and the history and facts behind the lesson.

We have been having fun with polymers, or long chains of molecules that link together to make slimy or rubbery things…just the kind of thing boys like. Here is a simple experiment using things you probably have around the house that will engage your young boys. They love making something they can play with.
First put one teaspoon of vinegar in a clean Mason jar.
Next, heat 1/2 cup of milk in a little pan on the stove until lumps form.
 Scoop out the lumps into the jar with vinegar. You may need to pour off the liquid really slowly to get to the lumps.
Let it all sit for about an hour.
You’ll notice a rubbery blob form.
You can shape it into a little round ball, and then let it sit and harden for a few hours on a paper towel.
What is the science behind it?
The vinegar and milk interact with each other. When you cook the milk, it separates into 2 parts; a liquid, and a solid that is made of fat, minerals, and a protein called casein. The vinegar interacts with the milk protein, making a polymer or a long chain of molecules that bend like rubber.
We use casein to make glue and plastics.
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  1. This is partly how we make paneer (Indian cheese). Never thought of it as a polymer, interesting!

  2. I just came over from All Things Beautiful this looks really neat.

  3. We've made the borax version – but this is diffrent – I like it :)

  4. Fascinating stuff. Great guest post. I haven't forgotten about my promise – we just didn't do anything lately that I thought would be a good fit.

  5. I've never seen this before. It's neat! It's a nice science lesson too. This was one of my favorite posts for this week and I've linked up to it here: http://play2grow.blogspot.com/2011/01/weekly-favorites-for-january-23-2011.html


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