Properties of Sulfuric Acid relating to Safety Precautions

98% sulfuric acid is almost completely molecular as it is not ionised, meaning it does not attack either iron or steel, as a passivating layer forms. It can be thus safely stored in steel or iron containers or transported in tankers. Steel is stronger than glass or plastic, and is less likely to rupture in an accident. It is preferable to transport concentrated rather than dilute acid as it is cheaper per mole of H2SO4 and allows transport in steel containers rather than more fragile glass or plastic.
Diluted sulfuric acid contains hydronium ions and vigorously attacks metals, meaning dilute acid must be stored in glass or plastic containers. This also means, when storing or transporting the acid, care must be taken to avoid contamination with water. This means the containers must be well sealed. It should be stored well away from metals (especially metal powders), bases and water, as exothermic reactions will occur. It should be stored away from wooden shelves or metal trays.