In an oxygen molecule, the two oxygen atoms are held together by a double bond with a bond energy of 495 kJ/mol. Using the balanced chemical equation (shown above), how much energy must be expended in breaking the O=O bonds?

The energy need to break this 0=0 bond is 495 kJ/mol

Explanation:

Step 1: Data given

oxygen molecule = O2

In an O2 molecule, the 2 O-atoms are held together by a double bond with a bond energy of 495 kJ/mol.

To break this chemical bound, it requires energy

2O (g) → O2 (g)

The bound energy of a double oxygen bound = 495 kJ/mol

Since we have 1 molecule (consisting in 2 O atoms)

The energy need to break this 0=0 bond is 495 kJ/mol

The energy used in breaking H-H bond is 495 kJ/mol

Explanation:

A chemical reaction consists in the formation of new substances (products) from others (reagents). In this process, reagent bonds are broken and new ones are formed in the products.

Bond energy is the energy needed to break a mole of bonds of a substance in a gaseous state. In the case of diatomic molecules with a single bond, it corresponds to the energy needed to dissociate 1 mol of said substance into the atoms that form it, as in this case with O₂

In this case you know the following reaction:

O₂ (g) → 2 O (g)

In this case 1 mole of O₂ reacts to form 2 moles of O. Then 1 O-O bond is broken.

The bond energy of O-O bond is 495 kJ/mol

Then, the amount of energy in breaking one moles of O2 is:

Amount of energy=1 mol * (bond energy of O-O bond)

Amount of energy=1 mol * (495 kJ/mol)

Amount of energy=495 kJ

Therefore the energy used in breaking H-H bond is 495 kJ/mol