First of all, in terms of chemical structure, the chemical formula of sodium tripolyphosphate is Na3PO4, which consists of one phosphorus atom and four oxygen atoms. The chemical formula of sodium nitrite is NaNO2, which consists of a nitrogen atom, an oxygen atom and a sodium ion. Their molecular structures are different, which leads to their different properties.

Secondly, chemically speaking, sodium tripolyphosphate is a colorless crystal, soluble in water and alkaline. It can form phosphate ions in water, has strong chelation, and can form stable coordination compounds with metal ions such as calcium ions. Sodium nitrite is also a colorless crystal, soluble in water and alkaline. It can be decomposed into nitrite ions in water, which is reducible and can react with amino compounds to form nitrosyl compounds.

Finally, in terms of application, sodium tripolyphosphate is often used as corrosion inhibitor, water treatment agent and food additive in industry. It can prevent metal corrosion and reduce the formation of scale. Sodium nitrite is mainly used as food preservative and color retention agent in food processing. It can inhibit the reproduction of bacteria and prolong the shelf life of food.