Answer : The change in enthalpy of the reaction is, -310 kJ
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given main reaction is,

The intermediate balanced chemical reaction will be,
(1)

(2)

(3)

Now we will reverse the reaction 1 and multiply reaction 1 by 2, reaction 2 by 2 and reaction 3 by 3 then adding all the equations, we get :
(1)

(2)

(3)

The expression for enthalpy of formation of
will be,



Therefore, the change in enthalpy of the reaction is, -310 kJ
Kirchhoff's circuit laws are two equalities that deal with the current and potential difference (commonly known as voltage) in the lumped element model of electrical circuits. They were first described in 1845 by German physicist Gustav Kirchhoff. This generalized the work of Georg Ohm and preceded the work of Maxwell.
Average speed = (total distance) / (total time)
Average speed = (4+7+1+2 blox) / (1 hour)
<em>Average speed = 14 blocks/hour</em>
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I'm gonna go out on a limb here and take a wild guess:
I'm guessing that there's another question glued onto the end of this one, and it asks you to find either her displacement or her average velocity. I'm so sure of this that I'm gonna give you the solution for that too. If there's no more question, then you won't need this, and you can just discard it. I won't mind.
Average velocity = (displacement) / (time for the displacement)
"Displacement" = distance and direction from the start point to the end point, regardless of how she got there.
Displacement = (4E + 7W + 1E + 2W)
Displacement = (5E + 9W)
<em>Displacement = 4 blocks west</em>
Average velocity = (4 blocks west) / (1 hour)
<em>Average velocity = 4 blocks/hour West</em>