Advertisements
Advertisements
Question
Why does pure nitric acid take on a yellowish brown colour when exposed to light?
Advertisements
Solution
Yellowish brown colour of nitric acid is due to the presence of nitrogen dioxide formed due to thermal decomposition of nitric acid.
APPEARS IN
RELATED QUESTIONS
Write balanced chemical equations for Action of hot and concentrated Nitric acid on copper
Give two chemical equations for the following:
Nitric acid showing as acidic character.
Name the oxide of nitrogen which turns brown on exposure to air. How is it prepared?
Name the following :
Gas produced in air during lighting.
Explain with the help of a balanced equation, the brown ring test for nitric acid.
Give reason for the following:
Aqua regia dissolves gold and platinum.
Give two chemical tests for nitric acid.
During a thunderstorm, the rainwater contains nitric acid. The nitric acid is formed as a result of three chemical reactions. Describe or write balanced chemical equation for these three reactions.
Explain the following:
Concentrated nitric acid appears yellow when it is left standing in a glass bottle.
X, Y and Z are three crystalline solids that are soluble in water and have a common anion.
To help you to identify X, Y and Z, you are provided with the following experimental observations. Copy and complete the corresponding inferences in (a) to (e).
- A reddish-brown gas is obtained when X, Y and Z are separately warmed with concentrated sulphuric acid and copper turning added to the mixture.
INFERENCE 1: The common anion is the ______ ion. - When X is heated, it melts and gives off only one gas which re-lights a glowing splint.
INFERENCE 2: The cation in X is either ______ or ______. - The action of heat on Y produces a reddish-brown gas and yellow residue which fuses with a glass of the test tube.
INFERENCE 3: The metal ion present in Y is the ______ ion. - When Z is heated, it leaves no residue. Warming Z with sodium hydroxide solution liberates a gas which turns moist red litmus paper blue.
INFERENCE 4: Z contains the ______ cation. - Write the equations for the following reactions:
- X and concentrated sulphuric acid (below 200°C). (One equation only for either of the cations given in INFERENCE 2)
- The action of heat on Y.
- Concentrated nitric acid is added to copper turnings kept in a beaker.
