$3.98 Project Mc2 Bath Fizz Experiment (regularly $20) at Walmart

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 Walmart has the Project Mc2 Bath Fizz Experiment on sale for just $3.98 (regularly $19.99).

Usually, you use the classic reaction of baking soda (a base) and vinegar (an acid) to create carbon dioxide gas bubbles. This time, we use citric acid instead of vinegar because it is a solid. You pre-mix it with baking soda, mold it into a ball, and then activate it later by putting the ball in water to create fizzy bubbles.