Safety Precautions with Sulfuric Acid

As sulfuric acid is very exothermic (when dissolving in water), several safety precautions are taken with the handling, storage, dilution and transportation of sulfuric acid.

Water placed in sulfuric acid is extremely dangerous, as the water completely ionises small amounts of water in concentrated amounts of sulfuric acid will boil and form an acidic mist which is highly acidic and damaging if inhaled. In order to prevent this dilution of sulfuric acid happens with small amounts of sulfuric acid added to large quantities of water or slowly over a period of time and allowed to cool. In contrast, concentrated solutions of other acids already contain enough water so they are mostly ionised meaning less heat is released.

Sulfuric acid is also:

  • A strong acid which can corrode metals and other materials and damage both the structure and function of living organisms.
  • It acts as a strong oxidising agent, which allows it to attack materials which are normally resistant to attack from hydrogen ions of simpler acids. it is also a strong dehydrating agent, easily destroying a wide range of organic materials (e.g. living tissue).

As such these precautions and procedures should be observed to ensure the safety of handlers:

  • Always wear protective googles, gloves and a lab coat, as concentrated H2SO4 causes serious damage to skin and clothing, charring it (see dehydration of sucrose).
  • When diluting H2SO4, add small volumes of the acid to large volumes of water to disperse heat whilst mixing thoroughly. During pouring of the liquid, pouring down the sides prevents splashing.
  • Work near a running supply of water. If the acid contacts the skin, it must be washed off rapidly with copious amounts of tap water (however with large spills onto the skin, wipe off excess first).
  • Have a supply of neutraliser (sodium carbonate or bicarbonate) in case it is split. It should be first isolated to prevent it spreading and the area evacuated in case of fumes. Sand and a bucket can be used to clear acid for neutralisation.
  • Store the acid in smaller, easier to handle bottles (<1L). Avoid dribbling acid down the sides of containers, and wipe off any as soon as possible if present. Always place the bottle in a drip tray to ensure that do not contact the bench or shelf.