Question

a burning Mg ribbon continues to burn in a jar of CO₂, although CO₂ is neither combustible nor a supporter of combustion. justify the fact

Answer 1

1. When Mg ribbon burns in the air,it follows the following combustion reaction :
$2Mg\left(s\right)+O_2\left(g\right)\to 2MgO\left(s\right)+heat$

2. The heat of combustion released in this reaction increases the temperature of the jar.
3. On high temperature,the CO₂ reacts with Mg left,according to the following reaction :
$2Mg\left(s\right)+C{O}_2\left(g\right)\to 2MgO\left(s\right)+C\left(soot\right)$

4. So,CO₂ niether support nor burn,it reacts with reactive Mg ,to give a displacement reaction.