1 c. citric acid (find in the canning
section of the grocery store or order online)
1 c. baking
soda
1/2 c. corn
starch
1/2 c. light
oil (canola oil, baby oil, almond oil or similar)
scent (extract
from the grocery store or essential oils from the hobby store work
great)
food coloring (optional)
small molds
Procedure: Combine the
first four materials in a bowl. Add scent and color to the degree
desired. (Be careful to use a spoon to work in the food
coloring -- it can stain your hands until it has substantially
soaked into the solids.) The mixture should be crumbly and
should smash together into a ball when squeezed in your hand.
Add extras if you like -- lavender petals, Epsom salts, sea salt --
use your imagination! Press the mixture into the mold of your
choosing. Craft molds are great, but you can also use lids,
cups, cupcake tins, plastic eggs -- just about anything that is
slightly flexible so you can pop out the bomb once hardened.
Wait at least 4 hours for the mixture to harden, then pop out.
Wrap to make great gifts! For the holidays, try using
peppermint scent and pressing into candy cane molds or round molds
that will look like peppermints. Or use pine scent and press
into tree molds!
Tip: Let the kids drop the
leftover crumbs into a bowl of water -- the fizzing and bubbling is
very entertaining! You can also mix the crumbs with Epsom
salts (easy to find at Walmart in the cosmetics/medicine area) and
package as scented fizzing bath salts.
The Science:
Citric acid is
an acid; baking soda is a base. When pressed together into a
paste, they do not react. But when dissolved together in a
solution, they cause a chemical reaction that gives off carbon
dioxide gas (the same gas humans exhale).
Acid:
a compound usually having a sour taste and capable of
neutralizing alkalis and reddening blue litmus paper, containing
hydrogen that can be replaced by a metal or an electropositive
group to form a salt, or containing an atom that can accept a
pair of electrons from a base. Acids are proton donors that
yield hydronium ions in water solution, or electron-pair
acceptors that combine with electron-pair donors or bases.
(Dictionary.com)
Base:
a) a compound that reacts with an acid to form a salt, as ammonia,
calcium hydroxide, or certain nitrogen-containing organic compounds.
b) the hydroxide of a metal or of an electropositive element or
group. c) a group or molecule that takes up or accepts protons. d) a
molecule or ion containing an atom with a free pair of electrons
that can be donated to an acid; an electron-pair donor. e) any of
the purine and pyrimidine compounds found in nucleic acids: the
purines adenine and guanine and the pyrimidines cytosine, thymine,
and uracil. (Dictionary.com)
Mixture:
an aggregate of two or more substances that are not chemically united and
that exist in no fixed proportion to each other. (Dictionary.com)
Solution: a
homogeneous, molecular mixture of two or more substances. (Dictionary.com)
