ally into enough cold water to make its concentration less than 5%, neutralizing it with aqueous sodium hydroxide, and washing the solution down the drain with a large excess of water.

Nitrate is most dangerous in the form of concentrated nitric acid (70% or higher), which is a potent oxidizing agent for organic materials and all other reducing agents. It can also cause serious skin burns. Dilute aqueous nitric acid is not a dangerous oxidizing agent and is not easily reduced by common laboratory reducing agents. Dilute nitric acid should be neutralized with aqueous sodium hydroxide before disposal down the drain; concentrated nitric acid should be diluted carefully by adding it to about 10 volumes of water before neutralization. Metal nitrates are generally quite soluble in water. Those of the metals listed in Table 7.1 as having a low toxic hazard, as well as ammonium nitrate, should be kept separate from oil or other organic materials because on heating such a combination, fire or explosion can occur. Otherwise, these can be treated as chemicals that present no significant hazard.

Nitrites in aqueous solution can be destroyed by adding about 50% excess aqueous ammonia and acidifying with hydrochloric acid to pH 1:



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