Question

colourless concentrated sulphuric acid in a test tube changes to blue on adding a small piece of copper to it why

Answer 1

Copper metal reacts with sulphuric acid and forms copper sulphate salt which is of blue colour alongwith evolution of hydrogen gas.

Answer 2

Hey dear,

● Answer -
Blue colour of the solution is due to formation of copper sulphate.


● Explanation -
When a small piece of copper is added to conc. sulphuric acid, copper sulphate is formed with release of hydrogen gas.
Cu + H2SO4 --> CuSO4 + H2

Copper sulphate being a salt of transition metal changes the soln from colourless to blue.

Hope this helps you.
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