The heat released during combustion in an excess of oxygen of 1 ton of coal with a mass fraction

The heat released during combustion in an excess of oxygen of 1 ton of coal with a mass fraction of carbon of 84 percent was.

Given:
m (coal) = 1 t = 1,000,000 g
ω (C) = 84%

To find:
Q1 -?

Solution:
1) C + O2 => CO2 + 395 kJ;
2) m (C) = ω * m / 100% = 84% * 1,000,000 / 100% = 840,000 g;
3) n (C) = m / M = 840,000 / 12 = 70,000 mol;
4) 1 mol C – 395 kJ;
70,000 mol C – Q1 kJ;
Q1 = 70,000 * 395/1 = 27,650,000 kJ.

Answer: The heat is 27,650,000 kJ.