Question

Question: Note the differences in length of time the splint burned in Part B #2 with and without heating the sodium hydrogen carbonate (NaHCO,). Explain why, in terms of the chemical reaction.

Answer 1

Oxygen is promoter of combustion and Carbondioxide is opposite of this , it doesnot support combustion .

NaHCO3 (Sodium Bicarbonate or sodium hydrogen carbonate) is used as fire extinguisher as it produces Carbondioxide on heating ( above 50°C) . When it is heated following reaction takes place :

2 NaHCO₃(s) Na CO₂ (s) + CO₂(g) + H₂O(g) - Due to presence of Co, combustion of Splint stop

As the time of burning the splint ,when sodium hydrogen carbonate is heated, is small it is because of production of Carbondioxide as can be seen from the reaction .( i.e. 2 seconds ).

In second case where splint is burnt without heating Sodium bicarbonate , availability of Carbondioxide is not there in excess to extinguish the fire , therefore splint burns for a longer time. (i.e. 9 seconds).