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Chemistry Question on Enthalpy change

Enthalpy of combustion of carbon to CO2 is –393.5 kJ mol–1. Calculate the heat released upon formation of 35.2 g of CO2 from carbon and dioxygen gas.

Answer

Formation of CO2CO_2 from carbon and dioxygen gas can be represented as:
C(s)+O2(g)→CO2(g)C(s) + O_2(g) → CO_2(g) △fH=–393.5 kJ mol−1△_fH = – 393.5\ kJ\ mol^{-1}
(1 mole=44 g)(1\ mole = 44\ g)
Heat released on formation of 44 g44\ g CO2=–393.5 kJmol–1CO_2 = – 393.5\ kJ mol^{–1}
Heat released on formation of 35.2 g CO2CO_2
=–393.5 kJmol−144 g×35.2 g\frac {– 393.5\ kJ mol^{-1}}{44\ g} \times 35.2\ g
= –314.8 kJmol–1– 314.8\ kJmol^{–1}