Question

When the half-reactions Br2 +2e- ? 2Br- and Na ? Na+ +e- are combined, the balanced redox equation is _____.
A.

Na + Br2 +e- ? Na+ + 2Br-

B.

2Na + Br2 ? 2Na+ + 2Br-

C.

Na + Br2 ? Na+ + 2Br-

D.

2Na + Br2 + 2e- ? 2Na+ + 2Br- + e-

Answer 1

(A) \(Br_2 +2e \rightarrow2Br^- \)

(B) \(Na \rightarrow Na^+ +e\)

you need to balance the number of electrons, so multiply (B) x 2

(B) \(2Na \rightarrow 2Na^+ +2e\)


now, add them up and cancel the electrons

(A+B) \(2Na +Br_2 +2e \rightarrow2Br^- +2Na^+ +2e \)