1.1 What is Chemistry?

http://www.ck12.org Chapter 22. Oxidation Reduction Reactions

FIGURE 22.1

Rust on a car caused by the oxidation of

iron.

The rusting process is often accelerated when the metal comes into contact with electrolytes, such as the salts used
to melt ice on streets in the winter.

Similarly, silverware will tarnish when exposed to some sulfur-containing compounds. The layer of black tarnish
(Ag 2 S) can easily be removed by cleaning the silverware with a mixture of aluminum and baking soda:

3 Ag 2 S(s) + 2 Al(s)→6 Ag(s) + Al 2 S 3 (s)

FIGURE 22.2

Tarnished silver. The object on the left

has tarnished. The plate on the right

and the object being held have both been

polished.

Many homes are heated by burning propane gas, which combusts in the presence of oxygen:

CH 3 CH 2 CH 3 + 5 O 2 →3 CO 2 + 4 H 2 O