is a widely used commercial method, as well as a laboratory method.
Another method of producing hydrogen is to displace it from the water
molecule by using a metal. To choose the metal you must be familiar with its
activity with respect to hydrogen. The activities of the common metals are shown
in Table 8.
TIP
Know the relative activity of metals.
Table 8. Activity Chart of Metals Compared to Hydrogen
As noted in Table 8, any of the first three metals will react with cold water;
the reaction is as follows:
Very active metal + Water = Hydrogen + Metal hydroxide
Using sodium as an example:
2Na + 2HOH → H 2 (g) + 2NaOH
With the metals that react more slowly, a dilute acid reaction is needed to
produce hydrogen in sufficient quantities to collect in the laboratory. This general
equation is:
Active metal + Dilute acid → Hydrogen + Salt of the acid
An example: