Question

carbon reacts with oxygen to produce carbon dioxide co₂(g), δhf = -393.5 kj/mol according to the equation. c(s) + 2o₂(g) → co₂(g) what is the enthalpy change of the reaction? use δhrxn = σ(δhf,products) - σ(δhf,reactants).

Explanation:

Step1: Identify reactants and products

Reactants are C(s) and O₂(g), product is CO₂(g). The standard - enthalpy of formation of an element in its standard state is 0 kJ/mol. So, $\Delta H_{f,C(s)} = 0$ kJ/mol and $\Delta H_{f,O_2(g)}=0$ kJ/mol, and $\Delta H_{f,CO_2(g)}=-393.5$ kJ/mol.

Step2: Apply the formula $\Delta H_{rxn}=\sum(\Delta H_{f,products})-\sum(\Delta H_{f,reactants})$

$\Delta H_{rxn}=\Delta H_{f,CO_2(g)}-(\Delta H_{f,C(s)} + \Delta H_{f,O_2(g)})$. Substitute the values: $\Delta H_{rxn}=-393.5-(0 + 0)=-393.5$ kJ/mol.

Answer:

-393.5 kJ