Question

Carbon reacts with sulphur to give carbon disulphide, which is an endothermic reaction, where $92kJ/mol$ of heat is absorbed. What will be the value of $\Delta H$, when $24g$ of carbon reacts?

Answer 1

We must have to know that in this reaction, one mole of carbon is reacted with two moles of sulphur in the presence of heat and there is a formation of two moles of carbon disulphide. The chemical reaction is,
$C + 2S + heat \to C{S_2}$
$\Delta H$ is the enthalpy change, and it is the total amount of heat absorbed or evolved in a reaction at constant pressure.

Complete answer:
We also remember to know that the given reaction is an endothermic reaction. Because, in this chemical reaction, the reactants absorb the heat energy from the surroundings and there is a formation of products. In an endothermic reaction, the value of enthalpy change, $\Delta H$ is always positive. And the energy of the products is always higher than the energy of reactants.
Here, one mole of carbon atom absorbing the heat, which means,
One mole of carbon = $12g$ of carbon
The amount of heat absorbed by $12g$ of carbon $= 92kJ/mol$
Hence,
The amount of heat absorbed by $1g$ of carbon$= \dfrac{{92}}{{12}}kJ$
Therefore, the amount of heat absorbed, $\Delta H$ by $24g$ of carbon$= \dfrac{{92}}{{12}}x24$
$= 184kJ$
It is an endothermic reaction. Thus, the value of absorbed heat, $\Delta H$ will be positive. Hence, the value of $\Delta H$ is equal to $+ 184kJ$.

Note:
We must have to know that the amount of heat absorbed in the given reaction is always positive. Because, the reaction is endothermic and it is equal to, $+ 184kJ$. In an endothermic reaction, the heat is absorbed from the surrounding by the reactants and will get the products. Here, the enthalpy of the product is always greater than the enthalpy of reactant and it takes place at constant pressure and constant temperature.