The reaction described above is a single-replacement reaction as Co was able to replace Au in the solution. The redox reaction involves a process in which one agent is reduced while the other one is oxidized. The ionic equation can be expressed as,
Co(s) + Au⁺(aq) --> Co³⁺(aq) + Au(s)
If we are to balance the equation such that equal number of electrons will be in both sides of the equation, this will become.
Co(s) + 3Au⁺(aq) --> Co³⁺ + 3Au(s)
