[AI0101]

Hi
I heated some NaClO to decompose it.at then end a white solid powder reminded.I dissolved the powder in water and tested its ph.That was a base so it should be NaOH

I guess chloride gas cant be stable again heat thus it evaporates from the liquid and when this takes place Cl separates from Hypochlorite and oxygen gas will be produced as well :

NaClO ====> Na + Cl2 + O2

sodium reacts with the water of the liquid and sodium hydroxide would be produced:

Na + H2O ====> NaOH + H2

is it right?

[AWK]

The main reaction of thermal decomposition is
3 NaClO → NaClO₃ + 2 NaCl
NaClO is also decomposed by CO₂ from air with evolution of Cl₂. Basic pH observed by You rather comes from sodium carbonate.

[Arkcon]

Hi
I heated some NaClO to decompose it.at then end a white solid powder reminded.I dissolved the powder in water and tested its ph.That was a base so it should be NaOH

A decent guess.  Might be wrong, but is at least a decent guess.

I guess chloride gas cant be stable again heat thus it evaporates from the liquid and when this takes place Cl separates from Hypochlorite and oxygen gas will be produced as well :

Not really following your here, typo, or language barrier.  Something like that.

NaClO ====> Na + Cl2 + O2

This is not a balanced reaction.  Its also pretty unlikely.  Producing free sodium metal is very energy intensive.  And it won't survive long with powerful oxidizers like chlorine and oxygen around.

sodium reacts with the water of the liquid and sodium hydroxide would be produced:

Na + H2O ====> NaOH + H2

is it right?

Lets test this hypothesis.  Did you get hydrogen gas?  If not, then this reaction, and the one above it, didn't happen.

[AI0101]

The main reaction of thermal decomposition is
3 NaClO → NaClO₃ + 2 NaCl
NaClO is also decomposed by CO₂ from air with evolution of Cl₂. Basic pH observed by You rather comes from sodium carbonate.

thanks.thats right salt and sodium chlorate is produced(I checked on wikipedia).how can I separate the NaCl from NaClO3 to get pure NaClO3?(I think heating is not an appropriate method)

[AWK]

Fractional crystallization will work. NaClO₃ is about ten times more soluble than NaCl in boiling water where us at room temperature solubility of both compounds are comparable.

[AI0101]

Fractional crystallization will work. NaClO₃ is about ten times more soluble than NaCl in boiling water where us at room temperature solubility of both compounds are comparable.

so I should utilize some sort of a net with small holes to filter the solution and take NaCl and heat the solution again?is there any better way?

[Arkcon]

You might get a powder or small crystals when you cool the saturated solution.  So you should use a filter paper, or maybe an absorbent towel