What Happens When You Mix Sulfuric Acid and Magnesium?

By Staff WriterLast Updated Apr 11, 2020 7:19:05 AM ET
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Magnesium readily reacts with sulfuric acid and forms hydrogen gas bubbles and aqueous magnesium sulfate after the reactants are consumed. The easiest way to see this reaction is to take a test tube of sulfuric acid and drop a small ribbon of magnesium into the clear liquid. The reaction is exothermic, meaning heat is given off in addition to the hydrogen bubbles.

The chemical equation shows magnesium (Mg) and sulfuric acid (H2SO4) on one side and magnesium sulfate (MgSO4) and hydrogen gas (H2) on the other. The solutions involved are colorless. If enough magnesium is used, magnesium sulfate drops out of solution to form a white salt. A small wooden splint, lit with a match, can be held over the glass tube to test for the hydrogen gas. Upon reaching the flame, the gas throughout the entire test tube ignites.

Magnesium sulfate has several applications. Commonly known as Epsom salts, magnesium sulfate treats pre-eclampsa and eclampsia. The substance replenishes electrolytes, serves as an anticonvulsant and decreases the rate of contractions, according to the National Institutes of Health.

Magnesium reacts with hydrochloric acid in a similar fashion. Hydrogen is given off in gaseous form, while magnesium chloride stays in solution after the reaction.