If you need to reverse the following reaction in order for it to be an intermediate reaction in a Hess's law problem, what would be the final value for the enthalpy of reaction you use for this intermediate reaction?

[tex]\[
C_2H_4 + 3O_2 \rightarrow 2CO_2 + 2H_2O, \Delta H = -1410 \text{ kJ}
\][/tex]

A. [tex]\(-1410 \text{ kJ}\)[/tex]
B. [tex]\(1410 \text{ kJ}\)[/tex]
C. [tex]\(-2820 \text{ kJ}\)[/tex]
D. [tex]\(2820 \text{ kJ}\)[/tex]



Answer :

To reverse the given reaction, we need to change the direction of the reaction, which in turn will change the sign of the enthalpy change (ΔH). The given reaction is:

[tex]\[ \ce{C2H4 + 3 O2 -> 2 CO2 + 2 H2O} \quad (\Delta H = -1410 \text{ kJ}) \][/tex]

When we reverse this reaction, the reactants become products and the products become reactants. The reversed reaction is:

[tex]\[ \ce{2 CO2 + 2 H2O -> C2H4 + 3 O2} \][/tex]

For the enthalpy change associated with the reverse reaction, the sign of ΔH will change. Therefore, the enthalpy change for the reversed reaction becomes:

[tex]\[ \Delta H = +1410 \text{ kJ} \][/tex]

Thus, the final value for the enthalpy of reaction you use for this reversed intermediate reaction is:

[tex]\[ \boxed{1410 \text{ kJ}} \][/tex]

So, the correct answer is B. 1410 kJ

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