The enthalpy change (ΔH) for the reaction CO+Cl_2→Cl_2 CO is not provided, and it would be needed to determine the numerical value.
To determine the enthalpy change (ΔH) for the reaction CO+Cl_2→Cl_2CO, the specific value of ΔH needs to be provided. The enthalpy change is a measure of the heat exchanged during a chemical reaction. It can be positive, indicating an endothermic reaction (absorbs heat), or negative, indicating an exothermic reaction (releases heat).
Without the given numerical value of ΔH for this particular reaction, it's not possible to specify whether the reaction is endothermic or exothermic. Once the numerical value is provided, the sign and magnitude of ΔH will indicate the heat flow associated with the reaction.