Question

Explain: Heat of formation of acetylene is $ + 54kcal$.

Answer 1

Hint:This question gives the knowledge about the heat of formation. Heat of formation is a type of heat or enthalpy of reaction. The unit of heat of formation is $kcal$. The heat of formation is the change in enthalpy which takes place on forming one mole of compound from its elements.

Complete step by step answer:
The heat of formation is the change in enthalpy which takes place on forming one mole of compound from its elements.. Heat of formation is a type of heat or enthalpy of reaction. The unit of heat of formation is $kcal$. It is generally denoted by $\Delta {H_f}$.
The reaction for the heat of formation of acetylene is as follows:
$2{C_{\left( S \right)}} + {H_2}_{\left( S \right)} \to {C_2}{H_4}_{\left( g \right)}$

The heat of formation of acetylene is $ + 54kcal$.

Additional information:
It is defined as the change in enthalpy which takes place on forming of a one mole of compound from its elements, at standard temperature $\left( {298K} \right)$ and pressure $\left( {1atm} \right)$. The unit of standard heat of formation is $kcal$. It is generally denoted by $\Delta H_f^ \circ $. Basically it is used to determine the standard heat of the reaction $\left( {\Delta {H^ \circ }} \right)$.The standard heat of formation is equal to the difference between the standard heat of formation of reactants and the standard heat of formation of products.

Note:
The concept that the heat of formation is the change in enthalpy which takes place on forming one mole of compound from its elements. The unit of heat of formation is $kcal$ and is generally denoted by $\Delta {H_f}$. Enthalpy is a thermodynamic property.Enthalpy depends upon internal energy,pressure and volume.