What happens when Magnesium is added to sulphuric acid?

This article explores the reaction involving the introduction of magnesium in sulfuric acid and its applications in the industry.

Introduction:

Magnesium (Mg) belongs to Group 2 (alkaline earth metals) in the periodic table and readily makes oxides due to its high reactivity. It is the eighth most common element found in our planet’s crust where can exists as magnesium oxide (MgO) when it reacts with oxygen and as magnesium hydroxide Mg (OH)₂ when it is introduced into water. 

It has a shiny and silvery-white appearance with a slight tint of gray color. In nature, the most common form of this element is the mineral dolomite (CaMg (CO3)₂), a double carbonate of calcium and magnesium and magnesite (MgCO₃). It is also found to make several alloys with other metals. It has two valence electrons, located in the 3s orbital which it can give away in the reactions with suitable candidates.

Next, sulphuric acid (H₂SO₄) also known as Oil of vitriol or Mattling acid, is a very common and important compound for industrial purposes. It is a diprotic acid (can donate two protons per molecule) with strong hygroscopic and oxidizing properties. Its molecule is in a tetrahedral shape due to the arrangement of all the participants in it.

When dissolved in water, it converts into hydronium ions (H₃O⁺) and hydrogen sulfate ions (HSO⁴⁻) making a very polar liquid. In pure form, it exists as a colorless and syrupy liquid. Note the atomic bonding in the molecule of sulphuric acid is covalence since all the bonds are covalent but when introduced in a solution like water, it ionizes into hydronium and sulfate ions.

Reaction of Magnesium Metal and Sulfuric acid

When you introduce magnesium in sulfuric acid with a high concentration of this acid, a vigorous exothermic reaction occurs. The hydrogen atoms from the ionization of sulphuric acid react with magnesium and oxidize it to produce hydrogen gas.

Next, the oxidized magnesium ions (Mg²⁺) react with the sulfate (SO₄²⁻) ions from sulphuric acid to form magnesium sulfate. During this reaction, sulfur dioxide is also released as a byproduct. The reaction can be stated as:

Mg  + H2SO₄ → MgSO₄ + SO₂ + 2H₂O

If you introduce magnesium in sulfuric acid with low concentration, then SO₂ is not released during the reaction. The release of sulfur dioxide gas happens due to the high temperature reached during the exothermic nature of the reaction with concentrated sulfuric acid. The reaction is as follows:

Mg + H₂SO₄ → MgSO₄ + H₂

As earlier mentioned, magnesium is much more reactive compared to other alkali metals and can react with sulphuric acid at room temperatures. But for other metals like copper, you may need to introduce external heat to the solution for initiation of their reaction.

Industry Applications:

Their reaction is very useful when producing different industrially important chemicals like ammonia and during the hydrogenation of fats and oils. The magnesium sulfate (MgSO₄) produced in the process has strong implications in different industrial sectors. The most significant use is its role as a fertilizer where it is used to increase magnesium and sulfur levels in soil.

This sulfate also finds its use in water treatment, as a laxative, and anticonvulsant agent, and during many industrially important processes for the production of paper, textiles, and adhesives. Moreover, the production of sulfuric acid in this reaction is used in the treatment of wastewater in cities. It is also used as a reducing agent in air pollution control devices and as a food preservative to prevent them from spoiling.

Wrapping Up:

To conclude, it can be stated that when we introduce magnesium in sulfuric acid, an exothermic reaction takes place when the acid is in high concentration. This produces magnesium sulfate, water, and sulphuric gas. If the acid used is diluted, it would only produce H₂ gas instead of SO₂ gas along with respective sulfates. The reaction has many significant applications in several industrial sectors.