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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: jamesweltz on June 02, 2007, 11:16:45 PM

Title: Decomposition of KNO3
Post by: jamesweltz on June 02, 2007, 11:16:45 PM

Does anyone know the products of the decomposition of KNO₃? Could it be KNO and O₂ or something completely different, such as KN₃ and O₂ or K₂O and N₂ and O₂?

Title: Re: Decomposition of KNO3
Post by: UnintentionalChaos on June 03, 2007, 12:07:34 AM

Standard thermal decomposition? IIRC it occurs at a fairly low rate, even at highly elevated temperatures, but it does break down releasing O2 and forming KNO2 (nitrate -> nitrite)

2KNO₃ -(heat)-> 2KNO₂ + O₂

Title: Re: Decomposition of KNO3
Post by: jamesweltz on June 03, 2007, 03:02:15 PM

At a higher temperature would it decompose to hyponitrite, KNO?

Title: Re: Decomposition of KNO3
Post by: UnintentionalChaos on June 04, 2007, 02:27:25 AM

Hyponitrite doesn't exist.

When heated further, nitrite probably breaks down into a mix of potassium oxide and peroxide while releasing N2 gas or nitrogen oxides.

Title: Re: Decomposition of KNO3
Post by: hmx9123 on June 08, 2007, 08:08:34 PM

'Hyponitrite' is actually called nitrosyl, and it does exist, though it isn't common.  It's pretty reactive, and not all metal nitrosyls are known.  A prep for sodium nitrosyl (NaNO) is in Brauer's Handbook of Preparative Inorganic Chemistry, v.1, p.514.  It is made from Na metal and NO gas in a tube furnace.  Though it may be a transitory stage in the decomposition of KNO3, I somehow doubt it.  I would expect to get potassium oxides and nitrogen if heated further as UnintentionalChaos suggests.

Title: Re: Decomposition of KNO3
Post by: jamesweltz on June 10, 2007, 12:21:42 PM

thanks
 :)