Which sentence describes the energy changes that take place when this chemical reaction occurs?

[tex]\[ N_2 + 3 H_2 \rightarrow 2 NH_3 \][/tex]

A. Energy is released to break bonds in [tex]\( N_2 \)[/tex] and [tex]\( H_2 \)[/tex] and absorbed when the bonds in [tex]\( NH_3 \)[/tex] form.

B. Energy is released when bonds in [tex]\( N_2 \)[/tex] and [tex]\( H_2 \)[/tex] break and when bonds in [tex]\( NH_3 \)[/tex] form.

C. Energy is absorbed to break bonds in [tex]\( N_2 \)[/tex] and [tex]\( H_2 \)[/tex] and to form bonds in [tex]\( NH_3 \)[/tex].

D. Energy is absorbed to break bonds in [tex]\( N_2 \)[/tex] and [tex]\( H_2 \)[/tex] and released when the bonds in [tex]\( NH_3 \)[/tex] form.



Answer :

To determine the correct statement about the energy changes in the chemical reaction
[tex]\[ N_2 + 3 H_2 \rightarrow 2 NH_3, \][/tex]
we need to consider the basic principles of bond breaking and bond forming:

1. Breaking Bonds: This process always requires energy because you are separating atoms that are bonded together, which means overcoming the attractive forces holding them together. This type of process is endothermic.
2. Forming Bonds: This process releases energy because atoms come together to form a more stable arrangement. This type of process is exothermic.

Given the reaction:
[tex]\[ N_2 + 3 H_2 \rightarrow 2 NH_3, \][/tex]

- Breaking Bonds:
- In the reactants, [tex]\(N_2\)[/tex] and [tex]\(H_2\)[/tex] molecules have strong triple bonds (in [tex]\(N_2\)[/tex]) and single bonds (in [tex]\(H_2\)[/tex]) respectively. To break these bonds, energy must be absorbed.
- Forming Bonds:
- In the products, [tex]\(NH_3\)[/tex] (ammonia) molecules are being formed. When the new N-H bonds in ammonia form, energy is released.

Putting it all together:
- Energy is absorbed to break the bonds in [tex]\(N_2\)[/tex] and [tex]\(H_2\)[/tex].
- Energy is released when new bonds form in [tex]\(NH_3\)[/tex].

So, the right statement describing these energy changes is:
D. Energy is absorbed to break bonds in [tex]\(N_2\)[/tex] and [tex]\(H_2\)[/tex] and released when the bonds in [tex]\(NH_3\)[/tex] form.