when you drop a dirty coin into a bottle of coke, why in a coule of hours does the coin come out shiny ?

Question: when you drop a dirty coin into a bottle of coke, why in a coule of hours does the coin come out shiny ?
- Keywords:
  chemistry,
  coin,
  coke,
  reaction,
  state
Asked by TomMiller69 to Sarah on 14 Nov 2014.
- Sarah Ashwood answered on 14 Nov 2014:
  
  Coke is a bit acidic – so when you put a dirty coin in it the acid dissolves the dirt on it and makes the surface appear shiny again.
  It’s kinda creepy when you think that we drink the stuff! But then stomach acid is also very acidic so it’s a similar idea really.

Question: when you drop a dirty coin into a bottle of coke, why in a coule of hours does the coin come out shiny ?