[chemistrie]

1. During electroplating copper (for example), the impure copper is made the anode. After passing through electricity, some impurities such as gold, silver and platinum will settle at the bottom of the container. Why they don't like other metal ions, like zinc ions, oxidise themselves?

2. Chlorine gas is used to sterliise the water of swimming pool, but sodium hypochlorite (NaOCl) is more preferrable. Why?

[Donaldson Tan]

chlorine is a gas while sodium hypochlorite is a powder. It is less hazardous to handle the powder than chlorine gas. Moreover, hypochlorite is the same active ingredient in aqueous chlorine that gives its oxidising power that kills bacteria.

in electroplating copper, the more reactive metal dissolves in the electrolyte. Copper in the impure metal block is more reactive than the other metal present.