Solution



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m = 400 g = 0.4 kg
c = 4200
= (22 + 273) - (12 + 273) = 10 K
E = 0.4 4200 10 = 16,800 J = 16.8 kJ

This means that 16. 8 kJ of heat is released when 0.98 g of ethanol is burned.

1 mole ethanol = 212 + 51 + 16 + 1 = 46 g

Therefore the burning of 46 g releases = 840 kJ

The reaction is exothermic.
Therefore heat of combustion = -840 kJ