Physical Science
Chapter 22: Acids, Bases, and Salts
• Try to identify 2 common acids and bases
which are commonly seen.
Acids
• An acid is a substance which gives off H+
ions when it is mixed with water.
Therefore, it always has hydrogen as part
of it’s formula.
Properties of Acids
• All acids have certain
distinctive properties.
These properties include:
-pH value below 7
-act as electrolytes (a liquid
which will conduct an electric
current)
-are often poisonous
more g
-acids taste sour
-are corrosive to metals and living
tissue
-turn litmus paper red
Different common acids
• Citric acid – found in
lemons and limes
• Hydrochloric acid (HCl)
– stomach acid
• Sulfuric acid
(H2SO4) – battery acid
• Acetic acid - vinegar
• Carbonic acid –
carbonated
beverages
• Nitric acid – TNT,
nitroglycerin
• Phosphoric acid –
detergents and
fertilizers
• Acid rain is rain that has a lower than normal
pH, making it more acidic.
This is caused by pollutants like sulfur and nitrogen
compounds mixing and reacting with moisture in
the air, to form compounds such as H2SO4, sulfuric
acid.
Derrick noticed that at the old cemetery near his
house, a lot of the headstones were weathered to
the point where they could hardly be read.
Derrick’s dad said that was due to the effects of
acid rain.
“How could that happen here”, asked Derrick. “We
live way out in the country.” Answer??
• Derrick then noticed that while a lot of the
headstones were weathered to the point where
they could hardly be read, others that were the
same age were still very clear.
• What’s up with that?
Bases
• Bases produce OH- ions in a solution
(water).
• Therefore, most bases have OH in their
formulas.
• Some general properties of bases
include the following:
-pH greater than 7
-taste bitter
-slippery
-corrosive to metals and living tissue
-turn litmus paper blue
-act as an electrolyte
Some common bases
• NaOH (lye) – used
in soaps and drain
cleaners
• NH3 (ammonia) –
use in household
cleaners and
fertilizers
• Aluminum hydroxide - deodorants
• Magnesium hydroxide - laxatives and
antacids
• Sodium bicarbonate – baking soda
pH
• The pH of a solution tells how basic or
acidic it is. 0-14
• A pH of 7 is completely neutral, and the
strength of the acid or base increases the
further away it is from 7.
• Acids and bases will
neutralize each other.
Neutralization is a chemical
reaction where the properties
of an acid and a base will
cancel each other out.
• Ex. Vinegar and baking soda
• An indicator is a material which will produce
predictable color change when exposed to
an acid or a base.
Litmus paper is a particular type of
indicator which turns red in an acid and
blue in a base.
Salts
• A salt is a compound which forms
when the negative ion from an acid
combines with the positive ion from
a base.
For example:
NaOH + HCl g NaCl + H20
The NaCl is a salt, Na+ and Cl-
Soap
• A soap is an
organic salt,
meaning a salt
with carbon in it's
formula.
• Most solid soap
will have NaOH in
it, while most liquid
soap will have
KOH.
The process of soap-making is called saponification.
g
+
animal fat
ashes
(tallow)
(lye)
soap
Detergents
• A detergent is a special type of soap
which does not produce a soap scum
in hard water.
• A hydrate is a compound with water
chemically attached, and part of it’s formula.
• Ex.: concrete, plaster of paris, sodium
polyacrylate
The End