What is true of the enthalpy value of an intermediate reaction?

A. It always has a negative enthalpy value

B. It is multiplied by 2 if the intermediate reaction is multiplied by 2

C. It is the same as the total enthalpy of reaction

D. If the intermediate reaction is reversed, its sign stays the same.

It's B.

B. It is multiplied by 2 if the intermediate reaction is multiplied by 2

Explanation:

intermediate reactions are reactions formed from the reaction mechanisms. They do not appear in the overall reaction because they are produced at the very early stage of the reaction. Hess law speaks much about the changes in enthalpies for series of intermediate reaction steps in order to deduce the overall change in enthalpy for a reaction.

Since, intermediate reaction are results of steps reactions, the do not really carry a negative enthalpy value.

The enthalpy value is usually multiplied by 2 if the intermediate reaction is multiplied by 2 because at that moment such intermediate reaction is a accompanied with a given enthalpy value.

The total overall enthalpy of the reaction is not the same as the intermediate reaction if we go by our definition, An intermediate reaction is still an ongoing reaction and not the final reaction.

When reversing an intermediate reaction, the signs doesn't remains the same but it changes from positive to negative or vice versa (i. e negative to positive)