Many metals react with other
chemicals; however, the rate of reaction varies among different
metals. Some metals react with water, some metals react with
acids, and finally some other metals are inactive and do not cause
any reaction with acids.
Variations in activity of metals
have many industrial applications. Some use such variations to
extract valuable metals such as silver from waste water of the film
development process. Some use variations in metal activity to do
plating without using electricity.