Answered

A student is asked to balance an equation by using the half-reaction method. He determines the two half-reactions as shown below.

[tex]\[
\begin{array}{l}
2 \mathrm{Br}^{-} \longrightarrow \mathrm{Br}_{2} + 2 \mathrm{e}^{-} \\
\mathrm{Cl}_{2} + 2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{Cl}^{-}
\end{array}
\][/tex]

What should he write as the final, balanced equation?

A. [tex]\(\mathrm{Cl}_{2} + 2 \mathrm{Br}^{-} \longrightarrow \mathrm{Br}_{2} + 2 \mathrm{Cl}^{-}\)[/tex]

B. [tex]\(\mathrm{Cl}_{2} + 2 \mathrm{Br}^{-} + 2 \mathrm{e}^{-} \longrightarrow \mathrm{Br}_{2} + 2 \mathrm{Cl}^{-}\)[/tex]

C. [tex]\(\mathrm{Cl}_{2} + 2 \mathrm{Br}^{-} \longrightarrow \mathrm{Br}_{2} + 2 \mathrm{Cl}^{-} + 2 \mathrm{e}^{-}\)[/tex]

D. [tex]\(\mathrm{Cl}_{2} + \mathrm{Br}^{-} + 2 \mathrm{e}^{-} \longrightarrow \mathrm{Br}_{2} + \mathrm{Cl}^{-} + 2 \mathrm{e}^{-}\)[/tex]



Answer :

GinnyAnswer
To balance the given chemical equation using the half-reaction method, follow these steps:

1. Identify the two half-reactions:
- Oxidation half-reaction: [tex]\( 2 Br^{-} \longrightarrow Br_{2} + 2e^{-} \)[/tex]
- Reduction half-reaction: [tex]\( Cl_{2} + 2e^{-} \longrightarrow 2 Cl^{-} \)[/tex]

2. Combine the half-reactions:
Add the two half-reactions together, ensuring that the electrons [tex]\( (e^{-}) \)[/tex] cancel each other out.

[tex]\[ \begin{array}{rcl} 2 Br^{-} & \longrightarrow & Br_{2} + 2e^{-} \\ Cl_{2} + 2e^{-} & \longrightarrow & 2 Cl^{-} \end{array} \][/tex]

Now, we sum the two half-reactions:

[tex]\[ 2 Br^{-} + Cl_{2} + 2e^{-} \longrightarrow Br_{2} + 2e^{-} + 2 Cl^{-} \][/tex]

3. Cancel the electrons:
The [tex]\(2e^{-}\)[/tex] on each side cancels out, leaving us with:

[tex]\[ 2 Br^{-} + Cl_{2} \longrightarrow Br_{2} + 2 Cl^{-} \][/tex]

The final, balanced equation is:

[tex]\[ Cl_{2} + 2 Br^{-} \longrightarrow Br_{2} + 2 Cl^{-} \][/tex]

Therefore, the correct answer is:
[tex]\[ Cl_{2} + 2 Br^{-} \longrightarrow Br_{2} + 2 Cl^{-} \][/tex]

Other Questions