Question

I use a copper flask for drinking water.
A few weeks after using it as my regular drinking water, I saw the inside of the flask blaken in color in patches.

I poured a lime, a spoon of salt and filled the flask with hot water, mixed the solution vigorously. Kept it like that for an hour.

When I poured out the water, it was of blue color!
This doesn't happen when I only keep water for 12 hours and empty the bottle.

I am still searching for what caused this turning of water to blue color.

Answer 1

Actually the black color was of copper rust which when mixed with lemon water gets off and if we make it more stronger(acidic) then copper may also get off, Those copper particles when mixed with water and the acid of lemon attain blue color solution. Because CuSO4.5H2O is always blue in color.