A simple method for distinguishing sodium nitrite NaNO2 from table salt

Sodium nitrite NaNO₂ has many uses, and can be used as heat treatment agent, foaming agent, metal surface treatment agent, bleaching and dyeing agent, etc. On the construction site, the freezing point of the inorganic salt solution is used as an antifreeze agent for cement construction. Because NaNO2 is a strong oxidant, eating NaNO₂ by mistake can oxidize hemoglobin containing +2 iron ions to methemoglobin with +3 iron ions, and lose the ability of hemoglobin to carry O₂ to exchange CO₂. Because NaNO₂ has the same salty taste as table salt, there have been many incidents of migrant workers being poisoned by cooking staff on construction sites mistakenly using industrial salt NaNO₂ as edible salt.

How to distinguish between NaNO₂ and ordinary table salt?

(l) heating method

If it is on the construction site, the salt to be tested can be heated in an iron pot (dry burning). Since the melting point of NaCl is 801°C, which is much higher than the melting point of NaNO₂ (271°C), if it melts and is accompanied by the formation of odorous gas The must be NaNO₂.

(2) Acid addition method

Add a small amount of salt to be tested into the test tube, add a few drops of hydrochloric acid or dilute sulfuric acid or vinegar, if there is reddish-brown NO₂ gas, it must be NaNO2.

2 NaNO₂ + 2H₂SO₄ = 2NaHS0₄ + NO₂ + N0 + H₂O