Question

Which is a spectator ion in the reaction between KOH and CoBr2? CoBr2(aq) Co2+(aq) K+(aq) OH– (aq)?

Answer 1

2KOH(aq) + CoBr₂(aq) → 2KBr(aq) + Co(OH)₂(s)

2K⁺ + 2OH⁻ + Co²⁺ + 2Br⁻ → 2K⁺ + 2Br⁻ + Co(OH)₂

K⁺ and Br⁻ are spectator ions

Answer 2

K+ and Br-

Step-by-step explanation:

A spectator ion is an ion which remains in the same form in both the reactants and product side of a chemical reaction i.e. it does not take part in the reaction.

The reaction between KOH and CoBr2 can be represented as:

2KOH (aq) + CoBr2(aq) → 2KBr(aq) + Co(OH)2(s)

In the above equation the three aqueous solutions, KOH, CoBr2 and KBr will ionize into respective ions unlike Co(OH)2 precipitate. The Total ionic equation can be depicted as:

2K+ + 2OH- + Co2+ + 2Br- → 2K+ + 2Br- + Co(OH)2

The K+ and Br- ions remain unchanged and can be cancelled out giving the net ionic equation:

2OH- + Co2+ → Co(OH)2

Thus, K+ and Br- are spectator ions