Question

click the \investigation\ tab and break all the bonds in the reactants. then, create all the bonds in the products. note the energy changes throughout the process. enter the correct answer in the box. the $delta h$ value for $ch_4 + 2o_2
ightarrow co_2+2h_2o$ is kj/mol.

Explanation:

Step1: Identify bond - energies

First, we need to know the bond - energies of the bonds in the reactants and products. For $CH_4$: C - H bond energy is approximately 413 kJ/mol (4 C - H bonds), for $O_2$: O=O bond energy is approximately 498 kJ/mol, for $CO_2$: C=O bond energy is approximately 799 kJ/mol (2 C=O bonds), and for $H_2O$: O - H bond energy is approximately 463 kJ/mol (2 O - H bonds per $H_2O$ molecule).

Step2: Calculate energy for breaking reactant bonds

In $CH_4 + 2O_2$:
The energy required to break bonds in $CH_4$ is $4\times413\ kJ/mol=1652\ kJ/mol$.
The energy required to break bonds in $2O_2$ is $2\times498\ kJ/mol = 996\ kJ/mol$.
The total energy required to break reactant bonds, $E_{break}=1652 + 996=2648\ kJ/mol$.

Step3: Calculate energy for forming product bonds

In $CO_2+2H_2O$:
The energy released when forming bonds in $CO_2$ is $2\times799\ kJ/mol = 1598\ kJ/mol$.
The energy released when forming bonds in $2H_2O$ is $2\times2\times463\ kJ/mol=1852\ kJ/mol$.
The total energy released when forming product bonds, $E_{form}=1598 + 1852=3450\ kJ/mol$.

Step4: Calculate $\Delta H$

$\Delta H=E_{break}-E_{form}$.
$\Delta H = 2648-3450=- 802\ kJ/mol$.

Answer:

• 802