Barrons SAT Subject Test Chemistry, 13th Edition

1. Water (aqueous) solutions of acids conduct electricity. The degree of
   conduction depends on the acid’s degree of ionization. A few acids ionize
   almost completely, while others ionize to only a slight degree. Table 10
   indicates some common acids and their degrees of ionization.


2. Acids will react with metals that are more active than hydrogen ions
   to liberate hydrogen. (Some acids are also strong oxidizing agents and will
   not release hydrogen. Somewhat concentrated nitric acid is such an acid.)


3. Acids have the ability to change the color of indicators. Some common
   indicators are litmus and phenolphthalein. Litmus is a dyestuff obtained
   from plant life. When litmus is added to an acidic solution, or paper
   impregnated with litmus is dipped into an acid, the neutral purple color
   changes to pink-red. Phenolphthalein is pink in a basic solution and
   becomes colorless in a neutral or acid solution.

TIP

Learn the names and formulas of these common acids.

Table 10. Degrees of Ionization of Common Acids

Completely or Nearly Completely Ionized
Moderately Ionized
Slightly Ionized

Nitric HNO 3

Oxalic H 2 C 2 O 4

Hydrofluoric HF

Hydrochloric HCI

Phosphoric H 3 PO 4

Acetic HC 2 H 3 O 2

Sulfuric H 2 SO 4

Sulfurous H 2 SO 3

Carbonic H 2 CO 3

Hydriodic Hl^

Hydrosulfuric H 2 S

Hydrobromic HBr^

(Most others)

4. Acids react with bases so that the properties of both are lost to form
   water and a salt. This is called neutralization. The general equation is:

Acid + Base → Salt + Water

An example is: