Question

Can burning takes place in the absence of oxygen ? Explain.

Answer 1

Oxygen is a very important substance to support combustion, but some substances still burn in the absence of oxygen.

• Substances that contain a high proportion of oxygen during decomposition supply oxygen for combustion. Example- Potassium nitrate(KNO₃)
• Magnesium ribbon burns even in the absence of oxygen in the atmosphere of nitrogen, which is not a supporter of combustion.

$\underset{\mathrm{Magnesium}}{3\mathrm{Mg}\left(\mathrm{s}\right)}+\underset{\mathrm{Nitrogen}}{{\mathrm{N}}_2\left(\mathrm{g}\right)}\stackrel{\mathrm{Burn}}{\to }\underset{\mathrm{Magnesium}\mathrm{nitride}}{{\mathrm{Mg}}_3{\mathrm{N}}_2\left(\mathrm{s}\right)}$

• Hydrogen gas burns in the atmosphere of chlorine to give hydrogen chloride gas.

$\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Chlorine}}{{\mathrm{Cl}}_2\left(\mathrm{g}\right)}\stackrel{\mathrm{Burn}}{\to }\underset{\mathrm{Hydrogen}\mathrm{chloride}}{2\mathrm{HCl}\left(\mathrm{g}\right)}$

Hence, it is clear combustion can take place without oxygen.