Disappearing Ink – Fun with Frederick and Fleming

Today’s experiment is actually on acids and bases, but Amy didn’t know that before we started.  Acids and bases are the opposites of each other. Pure water is considered neutral with acids being battery acid, vinegar and yes milk.  Examples of bases would be baking soda, soapy water and bleach.  Even though you think of acids as burning, both when in a high enough solution can cause chemical burns. Since they counteract each other, as you add a base to an acid, it becomes less acidic.  A real life scenario where you may do this would be in a fish tank or a back yard swimming pool where you want to have the water as neutral as possible.

Today we took some disappearing ink bought off the Internet and decided to look at the science behind it.  Disappearing ink is actually just a chemical agent that shows up blue when the liquid it is in is a certain strength base.  So, when exposed to an acid, the ph of the liquid neutralizes and the color disappears. The reason the color disappears in the air is because carbon dioxide is slightly acidic. You can make the color disappear faster by blowing on the disappearing ink or by adding a slight acid like vinegar.  Of course for the demonstration we took it to a whole new level with a carbon dioxide fire extinguisher, but need to tell people not to try this part at home.

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