Acids and Bases
Acids are substances that have a pH below 7 on
the pH scale. They are made up of a positively
charged ion and a negatively charged ion. The
positively charged ion within an acid is usually the
hydrogen ion (H+). The pH scale measures the
amount of H+ ions in a substance. The hydrogen
ion, H+, is a positively charged atom created
through the loss of one electron.
Bases are substances that have a pH higher than 7
on the pH scale. Group 7A elements on the
periodic table form negatively charged ions, such
as Cl- and have a -1 charge. They gain one
electron to make them negative.When these
negative ions bond to H+ ions, they form the
strong acids HCl, HF, HI and HBr. The name for
HCl Hydrogen Chloride. The names for the ions
contained within the acids are the names of the
elements. The -ine is dropped from the name of the
negative ion and -ide is added. The H+ ion also
combines with the OH- ion to form H-O-H
or water. Water is a neutral compound with the
pH of 7. Water, since it is a polar molecule, can act
as a solvent for an acid. Water molecules can dilute
acids by pulling acid molecules away from each
other and also separating acid molecules into their
ions. One reaction that can occur is the formation of
the H3O+ ion when an acid is mixed with water.
The H3O+ ion indicates the presence of a weak
acid. The chemical equation for this reaction is:
H-A + H2O ------> H3O+ + OH
Knowledge
and Comprehension
Words to Know:
1. Which group of elements usually pairs with H+ to
make
acids?
2. What happen to an acid when it mixes with
water?
Application, Analysis, Evaluation, and
Synthesis
3. Indicate the name of the following strong acids:
Formula Name
HF - ____________________________
HCL - ___________________________
HBr - ___________________________
HI - ____________________________
4. Describe how the H30+ ion is created.
5. What is the difference between an acid and a
base.
6. Explain how water can act as a solvent in the
presence
of an acid.
Acid:
Base:
pH Scale:
Neutral compound:
7. In terms of pH, explain how a strong acid and
water are
different.