Women tend to have more acidic skin than men. Based on the Activity Series of Metals, explain why most men wear 14 K gold rings, but most women wear 18 K gold rings.
2 answers
The copper that is alloyed with gold (24 k is pure gold; 18 k is 18/24 purity and 14 is 14/24 purity) reacts with the acid akin and other body fluids to give a green (sometimes black) compound of copper. It has been reported that many people can switch from 14 k gold to 18 k gold and their skin doesn't turn green. (That is not a universal cure; however.) I've given you a chemical reason for this observation (and I don't know how valid the observation is) but I suspect that far more people wear 14 k rather than 18 k because of the price.
I might point out here that nothing in my response uses the activity series of the metals as an explanation. Copper is BELOW H in the activity series; therefore, non-oxidizing acids will not react with copper unless some complexing material is present which is the case with body fluids AND it takes only a very small amount of copper ion to stain the skin green.
2 answers