Answer : The enthalpy change of reaction is -1800 kJ
Explanation :
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 final reaction is,
The intermediate balanced chemical reaction will be,
(1) 
(2) 
First we will multiply reaction 1 by 2 and reverse reaction of reaction 2 by 3 then adding both the equation, we get :
The expression for final enthalpy is,
![\Delta H=[n\times \Delta H_1]+[n\times (-\Delta H_2)]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5Bn%5Ctimes%20%5CDelta%20H_1%5D%2B%5Bn%5Ctimes%20%28-%5CDelta%20H_2%29%5D)
where,
n = number of moles
![\Delta H=[2mole\times (-1680kJ/mole)]+[3\times -(-520kJ/mole)]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5B2mole%5Ctimes%20%28-1680kJ%2Fmole%29%5D%2B%5B3%5Ctimes%20-%28-520kJ%2Fmole%29%5D)
Therefore, the enthalpy change of reaction is -1800 kJ
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The molecules in system #2 have a higher kinetic energy because they are at a higher temperature than molecules in system#1.
<h3>Heating of water molecules</h3>
Temperature is defined as a measure of the average kinetic energy of the molecules of a body. The higher the temperature of a body, the higher the kinetic energy of the molecules of the body.
In both systems, we have water molecules that have the same formula H2O. However, the molecules in system #2 have a higher kinetic energy because they are at a higher temperature than molecules in system#1.
Learn more about kinetic energy of molecules: brainly.com/question/2731193
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