Why Does Zinc react with Hydrochloric Acid?
Zinc has the tendency to react with hydrochloric acid by its nature. Zinc is an electropositive element. It is easily oxidized by hydrogen. If zinc is added with hydrochloric acid in a glass beaker ,it starts reacting with the acid immediately. Zinc reacts with the hydrochloric acid and Aluminum also does. However, aluminum reacts with the above acid very violently while zinc reacts slowly by releasing large quantities of hydrogen. At the end of the reaction, zinc will be soluble in HCl. The chemical reaction of zinc with hydrochloric acid is given below as:
Zn + 2HCl ÃƒÆ’Ã‚ ZnCl2 + H2
Electrochemical series is a group of metals which are listed according to their ability to react. The metal activity decreases from top to bottom in the list while the metal oxide activity increases from top to bottom. This series has the metals in the given order from top to bottom: Potassium, Calcium, Sodium, Magnesium, Aluminium, Zinc, Iron, Tin, Lead, Hydrogen, Copper, Silver, Mercury and Gold. These metals are not affected by the non-oxidizing acids. The electrochemical series is made based on the redox potentials of the metals. Metals with the most negative electrode potentials exist at the top and those with the most positive potentials exist at the bottom of the series. The electrode potential determines the direction of reducing the reaction equilibrium of the metal. The direction of the equilibrium whether to the right or to the left differs based on the number of electrons that are accumulated on the metal electrode with reference to the standard hydrogen electrode. This calculates the potential difference called as voltage.
The reducing capacity known as the capacity to get oxidized or the ability to give away electrons is higher for the metals that are at the top of the electrochemical series. As we go down the series, the metals take up the electrons easily and hence are good oxidizing agents. As zinc has more reducing capacity than hydrogen, it reacts with HCl and easily removes hydrogen and occupies its position as ZnCl2.