▁ ▁One ▁method ▁uses ▁mol ten ▁sod ium ▁nit rate ▁as ▁the ▁salt , ▁and ▁lead ▁which ▁is ▁ox id ized , ▁while ▁a ▁more ▁modern ▁method ▁uses ▁sc rap ▁iron ▁fil ings ▁to ▁reduce ▁the ▁nit rate . ▁ ▁A ▁more ▁commonly ▁used ▁method ▁involves ▁the ▁general ▁reaction ▁of ▁nit ro gen ▁ox ides ▁in ▁al kal ine ▁a que ous ▁solution , ▁with ▁the ▁addition ▁of ▁a ▁catal yst . ▁The ▁exact ▁conditions ▁depend ▁on ▁which ▁nit ro gen ▁ox ides ▁are ▁used , ▁and ▁what ▁the ▁ox id ant ▁is , ▁as ▁the ▁conditions ▁need ▁to ▁be ▁carefully ▁controlled ▁to ▁avoid ▁over ▁ox id ation ▁of ▁the ▁nit ro gen ▁atom . ▁ ▁S od ium ▁nit rite ▁has ▁also ▁been ▁produced ▁by ▁reduction ▁of ▁nit rate ▁sal ts ▁by ▁expos ure ▁to ▁heat , ▁light , ▁ion izing ▁radiation , ▁met als , ▁hydro gen , ▁and ▁electro ly t ic ▁reduction . ▁ ▁Chem ical ▁re actions ▁ ▁In ▁the ▁labor atory , ▁sod ium ▁nit rite ▁can ▁be ▁used ▁to ▁destroy ▁excess ▁sod ium ▁az ide . ▁ ▁A bove ▁ 3 3 0   ° C ▁sod ium ▁nit rite ▁decom poses ▁( in ▁air ) ▁to ▁sod ium ▁ox ide , ▁nit ric ▁ox ide ▁and ▁nit ro gen ▁dio x ide . ▁ ▁S od ium ▁nit rite ▁can ▁also ▁be ▁used ▁in ▁the ▁production ▁of ▁nit r ous ▁acid : ▁ ▁The ▁nit r ous ▁acid ▁then , ▁under ▁normal ▁conditions , ▁decom