Question

Given standard enthalpy of formation of co (-110 kj mol) co2 (-394 kj mol) the heat of combustion when one mole graphite burns

Answer 1

Answer : The heat of combustion when one mole graphite burns is, -394 kJ

Explanation :

Standard formation of reaction : It is a chemical reaction that forms one mole of a substance from its constituent elements in their standard states.

The balanced chemical equation for the standard formation reaction of gaseous carbon monoxide will be,

$C(graphite)+\frac{1}{2}O_2(g)\rightarrow CO(g)$  (incomplete combustion)

The standard enthalpy of $CO$ = -110 kJ/mol

The balanced chemical equation for the standard formation reaction of gaseous carbon dioxide will be,

$C(graphite)+O_2(g)\rightarrow CO_2(g)$   (complete combustion)

The standard enthalpy of $CO_2$ = -394 kJ/mol

The complete combustion of carbon graphite gives carbon dioxide as a product.

So, the heat of combustion when one mole graphite burns is, -394 kJ.