Safety
Like other corrosive acids and alkalis, drops of sodium hydroxide solutions can decompose proteins and lipids in skin, eyes or other living tissues viaamide hydrolysis and ester hydrolysis, which consequently causes chemical burns and may induce permanent blindness if it contacts eyes.[2][3] Solid alkali may also express its corrosive nature if there is water so protective equipment such as rubber gloves, safety clothing and eye protection should always be used when handling the material or its solutions.
Moreover, dissolution of sodium hydroxide is highly exothermic, and the resulting heat may cause heat burns or ignite flammables. It also produces heat when reacted with acids.
The standard first aid measures for alkali spills on the skin is, as for other corrosives, irrigation with large quantities of water. Washing is continued for at least ten to fifteen minutes.
Sodium hydroxide is corrosive to several metals, like aluminium which reacts with the alkali to produce flammable hydrogen gas on contact.
2 Al + 2 NaOH + 2 H2O → 3 H2 + 2 NaAlO2
2 Al + 6 NaOH + x H2O → 3 H2 + 2 Na3AlO3 + x H2O
2 Al + 2 NaOH + 6 H2O → 3 H2 + 2 NaAl(OH)4
Sodium hydroxide is also mildly corrosive to glass, which can cause damage to glazing or freezing of ground glass joints. Careful storage is needed.