Question

pick out the correct value for an exothermic reaction. 1358kj/mol -478kj/mol 0kj/mol -(-1000)kj/mol

Explanation:

In an exothermic reaction, heat is released. The change in enthalpy ($\Delta H$) for an exothermic reaction is negative.

• $1358\ \text{kJ/mol}$ is positive, which would be for an endothermic reaction (heat absorbed).
• $0\ \text{kJ/mol}$ implies no heat change, which is not an exothermic reaction.
• $-(- 1000)\ \text{kJ/mol}=1000\ \text{kJ/mol}$ (positive value, endothermic).
• $-478\ \text{kJ/mol}$ is negative, indicating heat is released (exothermic).

Answer:

-478kJ/mol