What is the total energy change for the following reaction: 2H2 + O2 -> 2H2O?

Given:
H-H bond: 436 kJ/mol
O-O double bond: 499 kJ/mol
H-O bond: 463 kJ/mol

A. -481 kJ/mol
B. + 445 kJ/mol
C. +63 kJ/mol
D. -730.5 kJ/mol

From the options provided the total energy change for the reaction :

 =  ( A ) ; - 481 kJ/mol

The Total energy change ( Δ ) in a reaction is calculated as  difference in energies between the reactants and products i.e.

Reactants Energy

= 2 * ( 436 kJ/mol ) + 1 * ( 499 kJ/mol )

= ( 872 + 499 ) kJ/mol  = 1371 kJ/mol

Product energy

= 4 * ( 463 ) kJ/mol

= 1852 kJ/mol

Hence Total energy ( )

= ( 1371 - 1852 ) kJ/mol

= -481 kJ/mol

Also from the results obtained we can conclude that the reaction is an endothermic reaction

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Explanation:

You calculate the energy required to break all the bonds in the reactants.

Then you subtract the energy needed to break all the bonds in the products.

                       2H₂  +  O₂ ⟶ 2H₂O

Bonds:          2H-H   1O=O     4O-H

D/kJ·mol⁻¹:     436     499        463

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.

0.88m hope i am correct : )