Question

How does the electrochemical series help in predicting the displacement of hydrogen by metals from dilute acids?

Answer 1

1. The electrochemical series helps in predicting the displacement of hydrogen by metals from dilute acids on the basis of their standard electrode potentials.
2. Metals which are placed above hydrogen in the electrochemical series have negative standard reduction potentials, and hence, they can easily lose electrons (i.e., they are more electropositive) and can displace hydrogen from dilute acids like HCl or H₂SO₄.
3. On the other hand, metals placed below hydrogen in the electrochemical series have positive standard electrode potentials and are less reactive; therefore, they cannot displace hydrogen from dilute acids.
4. For example, zinc (Zn) can displace hydrogen from dilute hydrochloric acid.
   \[\ce{Zn + 2HCl -> ZnCl2 + H2 \uparrow}\]
   But copper (Cu), which lies below hydrogen in the electrochemical series, cannot do so.

This application is based on the relative positions of metals and hydrogen in the electrochemical series.