Q.3.15.    A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?

Answers (1)
D Devendra Khairwa

The solution man used must be aqua regia. It is a solution of 3:1 mixture of conc. HCl and conc. HNO3. It has the property that gold dissolves in this solution.

After dipping the gold in the solution, the outer layer of gold dissolves and new surface is exposed which appears to be shiny. This is why the weigth of ornament is decreased.