Q2 of 29 Page 73

Write down the changes that will be seen in each instance and explain the reason behind it.

Two or three filings of copper were added to 10ml dilute nitric acid and stirred.

The changes observed when two or three filings of copper were added to 10ml dilute nitric acid and stirred are:

i. The solution changes to bluish red.


ii. A red toxic gas is evolved.


iii. Copper is completely consumed.


Explanation: The changes occur due to the following reaction


Cu + 4HNO3→ Cu(NO3)2 + 2NO2 + 2H2O


In the above reaction, the copper metal is oxidized by nitric acid. The nitrogen dioxide (NO2) formed in the reaction is so dangerous and toxic.


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