ANSWER
![\text{ }\Delta E_(REVERSE)\text{ = 31 KJ/mol}](https://img.qammunity.org/2023/formulas/chemistry/college/qx6lxcmjwyfzcupfxlw21ewbvuuvzwfz1c.png)
Step-by-step explanation
Given information
The energy on the product side = -40 KJ
The energy on the reactant side = -9kJ
Assume the reaction is a reversible reaction
![\text{ A }\rightleftarrows\text{ B}](https://img.qammunity.org/2023/formulas/chemistry/college/2hcrcycwmbcvhdkhjpax1frcq2u3jvelku.png)
For a reverse reaction, the product becomes the reactant and the reactant is the new product formed
Step 1: Write the general formula for calculating a change in energy
![\text{ }\Delta E_(reverse)\text{ = }\Delta E_(PRODUCT)-\text{ }\Delta E_(REACTANT)](https://img.qammunity.org/2023/formulas/chemistry/college/2pl7az7npw1gj53lmtlfrwfyzoiv403drs.png)
Step 2: Substitute the given data into the formula in step 1
![\begin{gathered} \Delta E_(reverse)\text{ = -9 - \lparen-40\rparen} \\ \Delta E_{REVERSE\text{ }}\text{ = -9 + 40} \\ \text{ }\Delta E_{reverse\text{ }}\text{ = 31 KJ/mol} \end{gathered}](https://img.qammunity.org/2023/formulas/chemistry/college/1al9s3b77wae0lvdmzpnto6g0j02bp1if3.png)