Question

An aqueous solution of blue copper(II) ions can react with chloride ions to form a yellow copper compound. The ionic equation for this reaction is: Cu² + 4CI- ⇌ [CuCl]²-

The forward reaction is endothermic. What two things can you say about the enthalpy change for the reverse reaction?

Answer 1

Since the forward reaction is endothermic (heat is consumed in the reaction) that means that the enthalpy change for the forward reaction is a positive value.
Therefore, i would say that the reverse or backward reaction is exothermic (heat is released in the reaction to the sorroundings) and that the enthalpy change is a negative value.