Question

LAST QUESTION YALLL PLZZZ HELP

Answer 1

-1104 kJ

Explanation:

C + O=O ⟶ O=C=O

Bonds: O=O 2C=O

D/kJ·mol⁻¹: 494 799

The formula relating ΔHrxn and bond dissociation energies (D) is

ΔHrxn = Σ(Dreactants) – Σ(Dproducts)

(Note: This is an exception to the rule. All other thermochemical reactions are “products – reactants”. With bond energies, it’s “reactants – products”. The reason comes from the way we define bond energies.)

For the reactants:

Σ(Dreactants) = 1 × 494 = 494 kJ

For the products:

Σ(Dproducts) = 2 × 799 = 1598 kJ

For the reaction :

ΔHrxn = 494 – 1598 = -1104 kJ

Answer 2

I've never done a reaction that involved just bond enthalpies before, so this is just a guess.

It's still products - reactants. The problem is the C=O bond. Do you count it once or twice? I'm going to choose once, but don't be surprised if it is incorrect.

Sum of the products - Sum of the reactants.

ΔH = 799 - 494

ΔH = 305

And that would be your answer to three places.