# What chemical equation proves that KHCO3 can extinguish a fire?

In a dry powder fire extinguisher, there is a chemical known as $\ce{KHCO3}$ and I was wondering how $\ce{KHCO3}$ works in a chemical equation to extinguish the fire.

• $$\ce{KHCO3 -> KOH + CO2}$$ – Zhe Jan 20 '17 at 2:54
• Please also see this answer which contains a subsection and a reference for how $\ce{NaHCO3}$ works. It is more that just the decomposition yielding $\ce{CO2}$; surpressing chain reactions tying up radicals is also key here (and heat of vaporisation and heat capacity). – Linear Christmas Jan 20 '17 at 13:00
• – Nilay Ghosh Jan 20 '17 at 14:48

According to this Wikipedia entry:

Decomposition of the bicarbonate occurs between 100 and 120 °C (212 and 248 °F):

$$\ce{2 KHCO3 → K2CO3 + CO2 + H2O}, \Delta H>0$$

So, you produce a nonflammable powder and two nonflammable gases, and you absorb heat from the fire in an endothermic reaction.

The picture here is more complex than just a chemical equation however. The $\ce{KHCO3}$ also acts as an energy-absorbing material and provides a solid surface on which free radicals can be destroyed.

• Tried \DeltaH and it came out bad. What was wrong? – Oscar Lanzi May 21 '17 at 9:58
• Thx @OscarLanzi . – airhuff May 21 '17 at 18:59
• Thx @NilayGhosh. – airhuff May 21 '17 at 19:00