Question

Consider the combustion of coal with a a given heat of formation in excess air, and answer the following question: http://i.imgur.com/QKPqD7U.png

Answer 1

Coal Combustion for Insufficient Air

By weight, the requirement of air for providing this much O₂ is After combustion of one gm carbon(C), product of combustion contains only 2.33 gm of CO and (5.75 - 1.33 =) 4.42 gm of N₂. From equation (1) and (2) it is clear that due to insufficient air combustion, the heat lose during 1 gm of coal combustion is (33.94 - 10.12) = 23.82 kj

Combustion of Coal

For sufficient air, We have already said that mass wise there is 23.2 % O₂ presents in air. Hence the amount of air required to provide 2.67 gm of O₂ is As per ideal combustion theory, after combustion of one gm carbon(C), product of combustion contains only 3.67 gm of CO₂ and (11.5 - 2.67 =) 8.83 gm of N₂