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Unit 8: Chemistry Page 17
take a look at a couple of terms What is an acid?
that folks use when talking about
When dissolved in water, an acid
solids. Click here to read more
has more hydrogen ions than
about solids.
regular water and a pH lower than
7.0. Generally, acids are sour in
Liquids
taste, change pH indicators red or
pink, react with metals to produce
A liquid has a definite volume
a metal salt and hydrogen, react
(meaning that you can’t compress
with bases to produce a salt and
or squish it into a smaller space),
water, and conduct electricity.
but takes the shape of its
Strong acids often produce a
container. Think of a water-filled
stinging feeling on mucus
balloon. When you smoosh one
membranes.
end, the other pops out. Liquids
are generally incompressible, which
What is pH?
is what hydraulic power on heavy
duty machinery (like excavators pH stands for “power of hydrogen”
and backhoes) is all about. and is a measure of how acidic a
substance is. We can make
Gases homemade indicators to test how
acidic (or basic) something is by
A gas doesn’t have a definite squeezing out a special kind of
volume or shape. You can squish juice (dye) called anthocyanin.
it, expand it, or shove it into a hole Certain flowers have anthocyanin
and it’ll happily go there. Gases in their petals, which can change
you are already familiar with are color depending on how acidic the
air (nitrogen and oxygen), helium soil is (hibiscus, hydrangeas, and
(in balloons), and neon (the red marigolds for example). The more
OPEN signs in stores). There’s also acidic a substance, the more red
xenon (in photography flash the indicator will become. We’ll be
lamps), argon (in fire extinguishers making several different indicators
and incandescent light bulbs), and in our experiments soon.
krypton (used in high-speed
photography flash lamps and by
astronomers for measuring stars).
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