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) Br2 +2e -> 2Br*-

(B) Na -> Na^+ +e) you need to balance the number of electrons, so multiply (B) x 2 (B) (2Na -> 2Na^+ +2e)

now, add them up and cancel the electrons (A+B) (2Na +Br_2 +2e ->2Br^- +2Na^+ +2e )