Reaction of copper with acids.
1 Drop a piece of copper foil into a test tube containing concentrated nitric acid. Describe what will happens/ observed?
Write equation to explain the reaction.
When a piece of copper foil is dropped into a test tube containing concentrated nitric acid, a reaction occurs. Initially, the copper foil will appear shiny and reddish-brown in color. As the reaction progresses, the color of the copper foil will start to change. It will turn black as a brown gas, nitrogen dioxide (NO2), is evolved. Meanwhile, the test tube will heat up due to the exothermic nature of the reaction.
The reaction can be explained by the following equation:
Cu + 4HNO3 → Cu(NO3)2 + 2NO2 + 2H2O
When a piece of copper foil is dropped into a test tube containing concentrated nitric acid, the following observations can be expected:
1. Fizzing or effervescence may occur, indicating the release of gas.
2. A brown gas may be released, which is nitrogen dioxide (NO2).
3. The copper foil will start to dissolve, gradually forming a blue-green solution.
The reaction between copper and concentrated nitric acid can be explained by the following equation:
Cu + 4HNO3 → Cu(NO3)2 + 2NO2 + 2H2O