How to prepare ferrous hydroxide

You can use ferrous sulfate solution and sodium hydroxide to react to produce ferrous hydroxide precipitate and sodium sulfate, and then filter to obtain ferrous hydroxide.

Inject a small amount of newly prepared ferrous sulfate solution into the test tube (in order to successfully prepare ferrous hydroxide, the ferrous sulfate solution must be heated first to remove dissolved oxygen), and then drop a few drops into it. Drop kerosene, use a rubber-tipped dropper to absorb the sodium hydroxide solution, insert the tip of the dropper under the solution surface in the test tube, and add the sodium hydroxide solution drop by drop.

The reaction equation is as follows: FeSO? 2NaOH==Fe(OH)?↓ Na?SO?.

Extended information

Ferous hydroxide is a white solid at normal temperature and pressure, but it is easily oxidized to Fe(OH)?, so it is mostly reddish brown.

Because there is oxygen dissolved in the solution and there is material exchange and energy exchange between the reaction system and the outside world, oxygen in the air is constantly dissolved into the solution, and the newly generated ferrous hydroxide is quickly oxidized into Iron hydroxide.

So it is difficult to observe the formation of white ferrous hydroxide precipitates during the experiment. We can only see the intermediate products of ferrous hydroxide converted into ferric hydroxide: some gray-green flocculent precipitates. , and then converted into red iron hydroxide precipitate.

The gray-green color is actually caused by the adsorption of ferrous ions in the solution by ferrous hydroxide.

Ferous hydroxide decomposes when heated and is insoluble in alkali solution, hardly soluble in water, and soluble in ammonium chloride. It dissolves rapidly in dilute acid to form ferrous salt and is a strong reducing agent in alkaline solution. When fine powder of ferrous hydroxide is sprayed into the air, it immediately burns and emits sparks.

Baidu Encyclopedia--Ferrous hydroxide