What happens when phenolphthalein is added after the reaction between sodium peroxide and water?

The phenomenon is: the solution turns red first and then fades.

2Na?O?+2H?O=4NaOH+O?

There is a base in the reaction product, so phenolphthalein will turn red, while Na?O? will also turn red when reacting with water. H?O? is generated, H?O? has bleaching properties and can also make the red color fade.

Sodium peroxide is one of the products of sodium burning in oxygen or air. Pure sodium peroxide is white, but the commonly seen sodium peroxide is light yellow because it is generated during the reaction. A small amount of sodium superoxide (NaO?, light yellow). Sodium peroxide is easily deliquescent and corrosive, so it should be kept sealed.

Extended information:

Sodium peroxide can react with water and acid to generate sodium hydroxide and hydrogen peroxide (hydrogen peroxide will decompose into water and oxygen), and can also react with Carbon dioxide reacts to produce sodium carbonate and oxygen.

Sodium peroxide can also oxidize some metals. For example, molten sodium peroxide can oxidize iron into ferrate (FeO); it can fuse some ores that are insoluble in acid to decompose the ores.

Sodium peroxide can oxidize elemental iron into ferrite containing FeO, and can also oxidize organic matter into ethanol and carbonate under normal conditions. , can also react violently with sulfides and chlorides.

Sodium peroxide has good thermal stability and can be heated to a molten state without decomposing.

In addition, sodium peroxide can also react with sodium, the equation is:

Na?O?+2Na=2Na?O

Phenolphthalein is white or slightly Yellowish fine crystals, insoluble in water but easily soluble in alcohol. Therefore, phenolphthalein is usually formulated into an alcohol solution. When the phenolphthalein reagent is dropped into water or a neutral or acidic aqueous solution, a white turbid substance will appear. This is because alcohol can be miscible with water in any proportion, causing the phenolphthalein, which is insoluble in water, to precipitate out of the reagent.

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